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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 113-117 
    ISSN: 1432-1041
    Keywords: nadolol ; nifedipine ; tachycardia ; cardiovascular response ; healthy volunteers ; pharmacokinetics ; exercise heart rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a placebo controlled exercise protocol using healthy volunteers the effects of nadolol 80 mg and 160 mg orally and of nadolol 80 mg during treatment with nifedipine 20 mg 8 hourly were compared. Resting systolic and diastolic blood pressures were reduced by both nifedipine (p〈0.05) and nadolol (p〈0.01) acting alone. An unexpected finding was that nifedipine alone significantly inhibited exercise tachycardia (p〈0.01) (8 to 12 h post dose). Predictably both doses of nadolol produced significant reduction in exercise tachycardia which was still apparent at 24 h. There was a linear relationship between log10 plasma nadolol concentration and reduction in exercise heart rate. The combined inhibitory effects of nifedipine and nadolol 80 mg on exercise heart rate showed partial additivity but did not summate. There was no pharmacokinetic interaction between the 2 drugs. The inhibition of exercise tachycardia by nifedipine, not previously documented, is consistent with an effect of the drug on the sinus node, as has been reported in in-vitro studies, and may contribute to the drugs efficacy in angina.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 171-175 
    ISSN: 1432-1041
    Keywords: pethidine ; drug metabolism ; pethidine metabolites ; renal excretion ; pharmacokinetics ; geriatrics ; old age ; meperidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a previous study old subjects were found to eliminate pethidine and its active metabolite norpethidine more slowly than young people. To investigate whether this was due to the decline in renal function with age, the urinary output of pethidine and its metabolites pethidinic acid, norpethidine and norpethidinic acid was compared in old and young patients. The cumulative urinary excretion of pethidine and pethidinic acid over 24 h was similar in old and young patients. The slower elimination rate of pethidine from plasma might therefore be due to slower biotransformation of pethidine to norpethidine and norpethidinic acid. The cumulative urinary excretion of norpethidine and norpethidinic acid during 24 h was significantly lower in old patients than in young: 2.7% versus 7.1% (p〈0.001), and 5.5% versus 10.5% (p〈0.001). The renal clearance of norpethidine was inversely correlated with age. Thus, the slower disappearance of norpethidine from plasma in old patients is due to slower renal excretion of this metabolite. The renal clearance of pethidine showed pH-dependence and was usually smaller than the creatinine clearance. In contrast, renal clearance of norpethidine was correlated with creatinine clearance and was of the same magnitude. The difference in renal handling may be explained by the more polar character of norpethidine compared to its parent compound. The present study shows that not only the excretion of unchanged drugs may decline with increasing age but also that of drug metabolites, which may therefore reach higher plasma levels in old patients. If they are pharmacologically active they will increase and prolong the response to medication and possibly increase the risk of side effects.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 317-320 
    ISSN: 1432-1041
    Keywords: bufuralol ; debrisoquine ; sparteine ; genetic/oxidative polymorphism ; metabolism ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Bufuralol is a beta-adrenoceptor blocking drug whose oxidative metabolism is under the same genetic control as debrisoquine and sparteine. The pharmacokinetics of bufuralol were studied in 10 healthy subjects (7 extensive and 3 poor metabolizers of debrisoquine) after oral and intravenous administration. In extensive metabolizers the systemic availability of bufuralol was 43%. Poor metabolizers were characterized by a considerable increase in systemic availability due to a corresponding decrease in hepatic first-pass metabolism. After oral administration of bufuralol non-linear kinetics may occur.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 333-337 
    ISSN: 1432-1041
    Keywords: cefotoxin ; renal failure ; peritoneal dialysis ; pharmacokinetics ; CAPD (continuous ambulatory dialysis) ; dialysate concentration ; intra peritoneal administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of cefoxitin was examined in 9 patients undergoing peritoneal dialysis for chronic renal failure. Cefoxitin was administered intraperitoneally in the dialysate fluid every 6 h for 24 h, in two different concentrations, 50 µg/ml and 100 µg/ml. The plasma half-life of cefoxitin was 20.2 h. The major route of elimination was non-renal, with a clearance of 8.0 ml/min. Peritoneal clearance was 4.1 ml/min. As expected, renal clearance was negligible. The peak plasma concentrations of cefoxitin at the two dose levels used were 7 µg/ml and 15 µg/ml, respectively, when assayed by HPLC, and 12 µg/ml and 24 µg/ml when determined by a microbiological assay. The cefoxitin concentration in the dialysate decreased from 50 µg/ml to 14 µg/ml and from 100µg/ml to 37 µg/ml during the 6 h of its retention in the peritoneal cavity.
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  • 5
    ISSN: 1432-1041
    Keywords: famotidine ; renal failure ; H2-receptor antagonist ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of a new, potent H2-receptor antagonist, famotidine, 20 mg i.v. was studied in 7 subjects with normal renal function and in 24 patients with varying degrees of renal impairment. The volume of distribution at steady state was 1.14 l/kg in normal subjects and was not altered in renal failure. The half-life of elimination was 2.59 h in normal subjects and was unchanged in mild renal failure (creatinine clearance, CLCR 90–60 ml/min/1.48 m2) but was increased to 4.72 h in moderate renal failure (CLCR 60–30 ml/min/1.48 m2), and to 12.07 h in severe renal failure (CLCR below 30 ml/min/1.48 m2). The cumulative urinary excretion and renal clearance of famotidine were correspondingly reduced in patients with impaired kidney function. In normal subjects and in patients with mild to moderate renal failure, about 70% of famotidine was excreted through the kidney, mainly by tubular secretion. In patients with a CLCR above 60 ml/min/1.48 m2 the normal daily dose of famotidine can be employed, but in those with a CLCR between 60 and 30 ml/min/1.48 m2 the dose should be reduced by half, and in patients with a CLCR below 30 ml/min/1.48 m2 a reduction by three quarters of the normal dose is recommended.
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  • 6
    ISSN: 1432-1041
    Keywords: prenalterol ; cardiac failure ; pharmacokinetics ; concentration-effect relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Prenalterol was administered as an intravenous infusion at three incremental rates (60, 120 and 240 nmol/min) to five patients with severe cardiac failure. Haemodynamic, hormonal and metabolic variables were measured at the same time as plasma prenalterol concentrations, and the pharmacokinetics of the drug were studied by following plasma concentrations and urinary excretion during and after the infusion. Concentration-dependent increases in cardiac index, stroke index and stroke work index were observed without increases in arterial pressure, heart rate or myocardial oxygen demand. The reninangiotensin-aldosterone system was stimulated, although the extent of stimulation varied among patients. No strong correlations were found between the logarithm of the plasma prenalterol concentration and effect. Plasma clearance of the drug was lower in cardiac patients than in normal volunteers, but a large decrease in renal clearance was partially balanced by an increase in nonrenal clearance. Over the observed range of concentrations, no deviation from linearity was evident, and plasma concentrations of about 150 nmol/l were effective in improving cardiac function without significant side-effects.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 659-664 
    ISSN: 1432-1041
    Keywords: BTS 49465 ; hypertension ; pharmacokinetics ; blood pressure effect ; heart rate effect ; side-effects ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic and haemodynamic effects of a 200 mg oral dose of BTS 49465 (7-fluoro-1-methyl-3-methylsulphinyl-4-quinolone) were investigated in a double-blind placebo controlled study. BTS 49465 was rapidly absorbed and cleared from the systemic circulation with a half-life of 1.6 h by oxidation to the sulphone metabolite. The metabolite was cleared with a half-life of 37.6 h. Saliva concentrations of both BTS 49465 and its metabolite correlated well with the plasma concentrations. Compared to placebo, BTS 49465 produced statistically significant reductions in blood pressure and increases in heart rate both supine and after a 60° head up tilt. The time course of the haemodynamic changes suggested that the sulphone metabolite contributed to the overall hypotensive response. Plasma Renin Activity was only marginally elevated and there was no evidence of acute fluid retention. BTS 49465 was well tolerated in terms of haematological and biochemical parameters and subjective side-effects.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 665-670 
    ISSN: 1432-1041
    Keywords: tocainide ; renal failure ; pharmacokinetics ; oral dosing ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma levels of tocainide have been followed after oral administration of 600 mg p.o. to 20 patients with renal failure due to various causes, and to 8 healthy controls. The peak plasma concentrations in the patients with pyelonephritis (3.80 µg/ml) and interstitial nephritis (3.74 µg/ml) but not in those with glomerulonephritis (3.17 µg/ml) differed from that in healthy volunteers (3.24 µg/ml). The renal clearance of tocainide was well correlated with the endogenous creatinine clearance and was dependent on urine pH. No difference in renal clearance was observed between the patients groups. It is suggested that the changes in plasma levels are a consequence of decreased renal clearance. Creatinine clearance was shown to be a poor estimator of tocainide clearance, which suggests that extrarenal clearance plays an important role in the handling of the drug in the body. The findings are used to suggest a safe dosage regimen.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 28 (1985), S. 77-84 
    ISSN: 1432-1041
    Keywords: β-Blockers ; debrisoquine metabolism ; extensive metabolizers ; genetic polymorphism ; poor metabolizers ; glucuronidation ; lipophilicity ; pharmacodynamics ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Although β-Blockers are structurally closely related, there are marked differences in the extent of metabolism, related mainly to relative lipophilicity. Lipophilic β-Blockers are metabolized by C-oxidative pathways and glucuronidation. Metabolism of lipophilic β-Blockers is important in determining pharmacokinetics, formation of active metabolites, stereoselectivity and isomer preference, and interphenotypic variation. The oxidative clearance of metoprolol, timolol and bufuralol is regulated/influenced by the debrisoquine hydroxylation gene locus. The metabolism of these lipophilic β-Blockers thus exhibits polymorphic characteristics, there being significant interphenotype differences in pharmacokinetics (bioavailability, peak plasma level, plasma terminal t1/2) between the poor and extensive metabolizers of debrisoquine. There are similar interphenotype differences in β-blocker pharmacodynamics in terms of β-blockade. A number of adverse effects of lipophilic β-Blockers have been hypothesized to predominate in the poor metabolizer phenotype including unacceptable bradycardia, loss of cardioselectivity, greater CNS side-effects, and interactions with drugs metabolized by the same polymorphic systems. However, objective evidence for this is lacking.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 27 (1985), S. 637-644 
    ISSN: 1432-1041
    Keywords: isosorbide-dinitrate ; pharmacokinetics ; analytical method ; bioavailability ; drug metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailabilities of a conventional and two slow release 20 mg isosorbide dinitrate (ISDN) formulations were compared after oral administration in a three way cross-over study in 8 male volunteers. In a further group of 6 male volunteers the pharmacokinetics and metabolism of ISDN were investigated after intravenous infusion of a median dose of 14.1 mg for 2.5 h. A new analytical procedure was developed for the determination of isosorbide-5-mononitrate-2-glucuronide (IS-5-MN-2-Glu) and of isosorbide (IS). Kinetic data analysis on a molar basis was performed by the program package KINPAK providing model independent parameters. The median elimination half-lives of ISDN, IS-5-MN, IS-2-MN and IS-5-MN-2-Glu were 0.7, 5.1, 3.2 and 2.5 h, respectively. The systemic clearance of ISDN was 3.7 l/min and the distribution volume 2521 (3.1 l/kg). Apart from IS-5-MN-2-Glu, with a renal clearance of 5.9 l/min which suggested substantial glucuronidation in the kidney, the renal clearances of ISDN, IS-5-MN, IS-2-MN and the corresponding amounts excreted were negligible. 27.8% of the administered ISDN was excreted as IS-5-MN-2-Glu (8.7%) and IS (19.1%). Calculations based on the two mononitrate metabolites formed from ISDN showed an incomplete recovery of 84.1%, leading to the assumption that a simultaneous denitration to IS must have occurred. The rate of denitration at each nitro group in ISDN was almost twice as high as for the same position in the corresponding mononitrate. The bioavailability of the conventional ISDN formulation was 19%, although complete absorption was indicated by comparison of the percentages of mononitrate metabolites formed after the different routes of administration. On the same basis the absorption of the two sustained release formulations was found to be poor.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 27 (1985), S. 649-656 
    ISSN: 1432-1041
    Keywords: bucindolol ; propranolol ; beta-adrenoceptor blockade ; intrinsic sympathomimetic activity ; vasodilator ; pharmacokinetics ; blood pressure ; plasma renin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The β-adrenoceptor blocking properties and pharmacokinetics of bucindolol 150 mg were compared to those of propranolol 80 mg and a placebo in a double-blind trial in 6 healthy volunteers. Heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures and peak expiratory flow rate (PEFR) at rest and during vigorous exercise, and plasma renin activity (PRA) at rest, were measured before and at intervals up to 24 h after oral administration of the drugs. Bucindolol reduced exercise tachycardia and decreased exercise PEFR, thus behaving as a non-selective β-adrenoceptor blocking drug. In contrast to propranolol, bucindolol did not reduce resting HR and PRA, probably because of its intrinsic sympathomimetic activity. It decreased resting DBP in relation to its peripheral vasodilator properties. The effects of bucindolol developed as early as 30 min after administration and lasted up to 24 h, whereas its Tmax and T1/2 were 1.6 and 3.6 h respectively. Comparison of the time courses of plasma bucindolol and the cardiac β-adrenoceptor blockade strongly suggests that in man bucindolol undergoes an extensive first-pass effect, leading to the formation of one or more active metabolites.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 27 (1985), S. 677-681 
    ISSN: 1432-1041
    Keywords: morphine ; analgesic ; pharmacokinetics ; intramuscular administration ; CSF/plasma-morphine levels ; CSF kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Morphine concentrations in plasma and cerebrospinal fluid (CSF) were measured in 58 elderly patients after intramuscular administration of 10 mg morphine. The assay employed gas chromatography with electron capture detection. From 49 of the patients undergoing urological procedures plasma and lumbar CSF samples were obtained simultaneously as spinal analgesia was given, and in addition, repeated venous samples were obtained over 4 hours from 35 of the patients. A plasma-morphine concentration vs time plot was drawn from the mean values and a CSF-morphine vs time plot was calculated by pooling individual CSF concentrations and using the sliding mean technique. The individual CSF/plasma-morphine concentration ratio vs time was also plotted. In addition, 2 or 3 CSF and plasma samples were collected simultaneously from 3 patients undergoing thoracotomy. Large interindividual variation in the CSF concentration was found. The peak CSF level was reached after 3 h and, following pseudoequilibrium, CSF-morphine levels appeared only slightly lower than those found in plasma. The availability to spinal CSF amounted to no more than 0.005% of the administered dose. CSF-morphine concentrations were not related to plasma protein or albumin concentrations.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 49-53 
    ISSN: 1432-1041
    Keywords: digoxin ; digoxin serum concentration ; drug interaction ; digoxin clearance ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An open, randomized, single-blind cross over trial to investigate phenytoin-digoxin interactions at steady state was performed in 6 healthy male volunteers. Coadministration of phenytoin caused a significant reduction in the elimination half-life of digoxin from 33.9 to 23.7 h and a diminution in AUC0–48 from 31.6 to 24.4 ng · ml−1 · h. Renal digoxin clearance was not significantly altered from 135.7 to 120.3 ml · min−1. Assuming no change in β-acetyldigoxin absorption, the in decrease time-course the serum digoxin concentration was due to a significantly increased total digoxin clearance from 258.6 to 328.3 ml · min−1. An insignificant reduction in the digoxin distribution volume from 749.4 to 668.0 l was also observed. No relevant change in the pharmacokinetic parameters (elimination half-life, area under the serum concentration time-curve, protein binding) of phenytoin was observed when phenytoin and digoxin were co-administered. The data suggest that with this drug combination the serum digoxin concentration should be carefully monitored and, if necessary, the daily digoxin dose should be increased.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 61-66 
    ISSN: 1432-1041
    Keywords: ergotamine ; pharmacokinetics ; blood/plasma concentration ratio ; blood pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ergotamine tartrate 0.5, 0.25 and 0.125 mg was administered i.v. to 6 volunteers in a cross-over study. Its pharmacokinetic characteristics were evaluated from plasma concentration-time data determined by HPLC. The clearance and volume of distribution were independent of the dose. The ratio between blood and plasma ergotamine concentrations in 4 subjects ranged from 0.41–0.67, indicating the lack of binding to blood cells. Ergotamine was found to be a high clearance drug, average 2.21/min/70kg body wt. suggesting extrahepatic clearance. A possible transient decrease in liver blood flow caused by ergotamine did not seem to affect the linearity of its kinetics.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 73-77 
    ISSN: 1432-1041
    Keywords: pirprofen ; arthritic disease ; pharmacokinetics ; elderly patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma concentrations of pirprofen were measured in 11 elderly arthritic patients and 6 healthy young volunteers at the beginning and end of 8 days treatment with 400 mg doses twice daily. The mean ages of the two groups were 74.5 and 21.8 years, respectively. There were no statistically significant differences in peak concentrations, times to peak, areas under the curve or terminal elimination half-lives between the groups after single dosing. Repeated dosing increased plasma drug concentrations in both groups but the extent was as predicted from the single dose data. Again there were no statistically significant differences between the groups, although pre-dosing plasma concentrations were higher in the elderly compared with the young individuals. The results of this relatively small study suggest that advancing age and arthritic disease appear to have little influence on the pharmacokinetics of pirprofen and no modification in the dosage recommendation in elderly patients without overt renal or hepatic impairment is indicated.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 109-113 
    ISSN: 1432-1041
    Keywords: griseofulvin ; skin blister fluid levels ; pharmacokinetics ; healthy subjects ; bioavailability ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Griseofulvin and 6-demethylgriseofulvin (6-DMG) in plasma, suction blister fluid (SBF) and cantharides blister fluid (CBF) and urinary excretion of 6-DMG, were evaluated following administration of single oral doses of an ultramicrosize and a microsize formulation of griseofulvin to 6 healthy volunteers. The bioavailability of griseofulvin was higher following the ultramicrosize formulation when 64% of the dose was recovered (via metabolites) versus 52% after the microsize preparation. Penetration into skin blister fluid was delayed as compared to plasma levels; the peak concentration in plasma was observed at 3–4 h, whereas griseofulvin in CBF increased up to 6 h. The terminal half-live was calculated from plasma levels to 9.3 h. The half-lives calculated from SBF and CBF concentrations were 9.2 and 9.8 h, respectively, (n=5). In plasma 84% of griseofulvin was bound to proteins, predominantly to albumin; binding in SBF and CBF was 72 and 82%, respectively. 3 h after drug administration the free concentration in plasma significantly exceeded the free concentrations in SBF and CBF. Distribution equilibrium between plasma and skin blister fluid was observed after 27 h. Thus, during chronic administration, the plasma griseofulvin level should reflect its concentration in the target organ.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 115-117 
    ISSN: 1432-1041
    Keywords: enprofylline ; theophylline ; pharmacokinetics ; patients ; theophylline requirement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In patients requiring a high or low dose of theophylline the pharmacokinetics of theophylline and enprofylline were studied. The low-dose group took an average daily dose of 8.91 mg/kg body wt. and the high-dose group 24.75 mg/kg body wt. The average half-life of theophylline in the former was 7.11 h and in the latter 4.72 h. The average clearances (CL) of theophylline were 2.83 and 4.58 l/h, respectively. The daily oral intake of theophylline was negatively correlated with the theophylline t1/2 (r=−0.63). While the t1/2 of enprofylline was similar in the two groups, CL and volume of distribution (Vc) were slightly (about 30%) but significantly higher in patients requiring a high dose of theophylline. CL of enprofylline did not correlate with CL of theophylline, nor was the Vc of the two drugs correlated. Interindividual variability in t1/2 and CL was considerably lower for enprofylline than for theophylline.
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  • 18
    ISSN: 1432-1041
    Keywords: trimazosin ; cimetidine ; pharmacokinetics ; alpha-adrenoceptor antagonism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of cimetidine treatment on the pharmacokinetics and pharmacodynamics of single doses of trimazosin was studied in 6 normotensive volunteers. Co-administration of cimetidine did not significantly affect the overall magnitude of the hypotensive effect of trimazosin. However, the time profile of the blood pressure response was significantly modified particularly with attenuation of the delayed component. Co-administration of cimetidine did not alter alpha1-adrenoceptor antagonism by trimazosin. There was no significant change in the clearnace and volume of distribution of trimazosin but there was a significant reduction in the area under the concentration-time curve for the metabolite, 1-hydroxytrimazosin. The reduction in the AUC of 1-hydroxy-trimazosin corresponds in time with the attenuation of the delayed hypotensive response. This is consistent with the suggestion that the delayed hypotensive response is related to an active metabolite, probably 1-hydroxytrimazosin.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 337-343 
    ISSN: 1432-1041
    Keywords: piretanide ; renal failure ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Piretanide 60 mg was administered intravenously over 30 min to 15 men with different degrees of renal failure. The mean piretanide serum concentration at the end of the infusion period was 5.72±1.51 µg/ml. Serum piretanide concentration-time curves declined biexponentially and 24 hours after medication the serum level had fallen to less than twice the detection limit. The terminal half-life ranged from 1.63 to 3.44 h. A relationship to creatinine clearance was not demonstrable. The mean metabolic clearance of piretanide was 107.7±47.6 ml/min/1.73 m2 body surface area and was the same as that reported for healthy subjects. The renal clearance of piretanide ranged from 3.33 to 43.9 ml/min/1.73 m2 body surface area and very closely correlated with the creatinine clearance (p〈0.01). Its renal clearance dependend principally on active secretion of the drug into the tubule, and glomerular filtration appeared unimportant. There was a close relationship between the amount of piretanide excreted in the urine and the creatinine clearance. Because the diuretic effect of piretanide depends on the concentration of the drug in the tubule, the observed correlation might be of use in evaluating the appropriate dosage of piretanide in patients with renal failure. The present data suggest that single daily doses of piretanide will not result in accumulation, even when high doses are administered to patients with advanced renal failure.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 345-349 
    ISSN: 1432-1041
    Keywords: pefloxacin ; renal insufficiency ; pharmacokinetics ; haemodialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of pefloxacin has been studied after a single intravenous infusion of 8 mg·kg−1 in 15 male patients with various degrees of renal failure. No difference in distribution or elimination of the drug was observed between patients with mild or severe renal impairment. The mean volume of distribution (Vd area) and the mean plasma clearance were 2.03l·kg−1 and 121.3 ml·min−1, respectively. The mean apparent elimination half-life was 13.5 h. These values are close to those observed in healthy subjects. No accumulation of the active N-desmethylmetabolite was observed in cases of severe failure as compared to mild impairment; its apparent elimination half-life was about twice that of the parent drug. The efficacy of a 4 h haemodialysis in 6 additional anuric subjects done to remove pefloxacin from the body was poor.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 351-354 
    ISSN: 1432-1041
    Keywords: griseofulvin ; skin blister fluid ; plasma concentration ; blister fluid concentration ; pharmacokinetics ; microsize formulation ; urinary excretion ; bioavailability ; different formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Griseofulvin was administered orally to 6 healthy volunteers for 6 days. The subjects received 500 mg of a microsize formulation and 330 mg of an ultramicrosize formulation, according to a cross-over design. The drug was determined in plasma, suction blister fluid (SBF) and cantharides blister fluid (CBF) following the last dose. Urinary excretion of the main metabolites 6-demethylgriseofulvin (6-DMG) and its glucuronic acid conjugate was also measured. The pharmacokinetic parameters were compared with those obtained from a recent single dose experiment. On repeated administration, the bioavailability of griseofulvin was significantly lower from the microsize formulation; the urinary recovery of total 6-DMG was 33.8% versus 53.6% on administration of the ultramicrosize material. Bioavailability was reduced as compared to ingestion of a single dose. The reduction was more prominent following the microsize (36%) than the ultramicrosize (17%) formulation. Penetration into skin blister fluid was not altered as compared to the single dose experiment. Relative areas under the blister fluid-time curves amounted to 51% (SBF) and 80% (CBF) of the area under the plasma level-time curve. The concentration of unbound griseofulvin in these body fluids was identical throughout the entire dosage interval. Unbound griseofulvin levels were low in comparison with the minimum inhibitory concentrations for strains of trichophyton and microsporum.
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 395-399 
    ISSN: 1432-1041
    Keywords: Ro 31-1118 ; cardioselectivity ; hypertension ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five patients with mild hypertension were given single oral doses of Ro 31-1118 (10, 20, 40, and 80 mg) and placebo in a randomized, double-blind, within-patient study. Plasma concentrations of Ro 31-1118 and supine, standing, exercise, and post-exercise heart rates and blood pressures were measured before and at regular intervals after drug administration. The pharmacokinetic data were consistent with a one-compartment model with first-order absorption and a variable time lag. Peak plasma concentrations and area under curve were linearly related to dose, whereas time to peak concentration, half-time, clearance and apparent volume of distribution were dose-independent. There was a reduction in exercise and post-exercise heart rate of approximately 10% after 10 mg and 20 mg Ro 31-1118, and of approximately 15% after 40 mg and 80 mg. At all doses standing systolic blood pressure was reduced by approximately 5%. A similar fall was seen in exercise and post-exercise systolic blood pressures. There was no substantial effect of Ro 31-1118 on supine or standing heart rates nor on diastolic blood pressure. No adverse effects were reported. It is concluded that Ro 31-1118 has linear pharmacokinetics over the dose range 10–80 mg, and has a weak antihypertensive effect when administered in single doses to patients with mild hypertension.
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  • 23
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    European journal of clinical pharmacology 29 (1985), S. 405-411 
    ISSN: 1432-1041
    Keywords: bornaprolol ; propranolol ; beta-adrenoceptor blockade ; duration of action ; pharmacokinetics ; plasma renin activity ; bronchoconstriction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The β-adrenoceptor blocking effects and pharmacokinetics of bornaprolol (FM 24), a new β-adrenoceptor blocking agent, have been compared with those of propranolol and a placebo in a double-blind trial in 6 healthy volunteers. Heart rate, systolic and diastolic blood pressures and peak expiratory flow rate were measured at rest and at the end of 3 min vigorous exercise on a bicycle ergometer, before and 2, 24 and 48 h after single oral doses of bornaprolol (120, 240 and 480 mg) and propranolol (40, 80 and 160 mg). Plasma renin activity at rest and the plasma concentrations of the two drugs were determined. Bornaprolol significantly reduced resting heart rate, dose-dependently lowered exercise-induced tachycardia and decreased peak expiratory flow rate and plasma renin activity. In addition, exercise-induced tachycardia was significantly reduced by bornaprolol up to 48 hours after drug intake (pharmacodynamic half-life approximately 63–86 h) and there was a correlation between this reduction and the log plasma bornaprolol concentration over the 48-h period. Thus, bornaprolol behaved in man as a non-cardioselective and long-lasting β-adrenoceptor blocking drug, probably devoid of intrinsic sympathomimetic activity.
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  • 24
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    European journal of clinical pharmacology 28 (1985), S. 205-212 
    ISSN: 1432-1041
    Keywords: adriamycin ; cancer patients ; infusion ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma pharmacokinetics of adriamycin has been studied in 21 cancer patients (31–85 years old) without liver tumours after short (3.00 min) and prolonged (45 min-16h) i.v. infusions. The area under the plasma concentration-time curve and the maximum plasma concentration compensated for dose variation showed a more than 3-fold individual variation. The pharmacokinetics of adriamycin was linear. There was no pharmacokinetic rational for variation of the dose with the age of the patients. There was good agreement between the measured plasma concentration-time curves for prolonged infusions and curves predicted from pharmacokinetic data from short term infusions.
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  • 25
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    European journal of clinical pharmacology 28 (1985), S. 197-204 
    ISSN: 1432-1041
    Keywords: triprolidine ; BW 825C ; pharmacokinetics ; pharmacodynamics ; sedation ; intradermal histamine ; human performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The new H1-receptor antagonist BW 825C and triprolidine (2.5 and 5 mg) were administered to 12 healthy male volunteers in a double blind placebo controlled, balanced, crossover design. Histamine antagonism was measured by assessment of flare and weal areas after intradermal injection of histamine. The 2 compounds were approximately equipotent in blocking the flare and weal response to intradermal histamine and had a similar duration of action. Triprolidine impaired performance of vigilance and reaction time (p〈0.05) compared with placebo while BW 825C did not. Drowsiness measured using visual analogue scales followed both triprolidine treatments, but not BW 825C. BW825C had a plasma half-life (t1/2) of 1.7±0.2 h and triprolidine of 4.6±4.3 h. The peak plasma level of BW 825C was approximately 6 times that of triprolidine. It was concluded that BW 825C might be a clinically active H1-antagonist with reduced sedative side-effects.
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  • 26
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    European journal of clinical pharmacology 28 (1985), S. 213-219 
    ISSN: 1432-1041
    Keywords: thiamine ; plasma level ; pharmacokinetics ; nonlinear renal elimination ; assay for clinical use
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A sensitive assay for thiamine suitable for clinical use has been developed. It is based on precolumn oxidation of thiamine to thiochrome followed by HPLC-separation and fluorescence detection. The assay is applicable to various biological materials, including human plasma. The minimum amount detectable was 5 fmol, minimum plasma concentration 0.5 nmol/l and minimum sample volume 0.3 ml plasma. Each chromatographic run took 3 min. Inter- and intra-assay relative standard deviations (RSD) were 8.3% and 6.3%, respectively, at a stock plasma concentration of 10.8 nmol/l. At 38.8 nmol/l, interassay RSD was reduced to 3.4%. The recovery of 5 nmol/l added thiamine was 102 (SD±17)%, that of 30 nmol/l was 94±5%. Plasma levels in 91 volunteers ranged from 6.6 to 43 nmol/l, showing a log normal distribution with a median of 11.6 nmol/l. Thiamine kinetics were studied in plasma and urine from 8 men after intravenous and oral doses of 50, 100 and 200 mg thiamine hydrochloride. In all individuals, nonlinear renal elimination kinetics were demonstrated by plotting the fractional amount of thiamine excreted unchanged in urine against the corresponding area under the plasma concentration — time curve.
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  • 27
    ISSN: 1432-1041
    Keywords: amiodarone ; warfarin ; drug interaction ; metabolism ; inhibition ; plasma concentration ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Potentiation of the anticoagulant-effect of warfarin by amiodarone was studied in 30 patients. Thirteen received both drugs concurrently, and 17 received warfarin alone and the combination sequentially. Warfarin doses were adjusted to maintain the prothrombin time between 25–30% of control and its kinetics were compared to those in 20 control patients who received warfarin alone. Potentiation occurred in 28/30 patients, presenting as a 35%–65% reduction in the required dose of warfarin, and was correlated with the dose of amiodarone (r=0.77, p〈0.01). The free warfarin fraction was not affected by amiodarone (1.8% vs 1.6% in the controls). Warfarin clearance was lower in amiodarone-treated patients than in the controls (1.4 vs 3.1 ml/min, p〈0.01) with similar plasma concentrations (1.5 vs 1.2 µg/ml) despite administration of lower doses (23.3 vs 39 mg/week respectively). The amiodarone concentration was significantly correlated with the warfarin concentrations independent of the effect of amiodarone on the dose of warfarin. Amiodarone hat no effect on prothrombin other than through its actions on the dose and plasma concentration of warfarin. The mechanism of the amiodarone-warfarin interaction is pharmacokinetic through dose — and concentration — dependent inhibition of warfarin elimination.
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  • 28
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    European journal of clinical pharmacology 28 (1985), S. 411-417 
    ISSN: 1432-1041
    Keywords: ketanserin ; ketanserinol ; pharmacokinetics ; age ; healthy volunteers ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of ketanserin has been examined in a cross-over experiment in 21 elderly subjects (aged 59–72 years) by administration of tablets (40 mg), solution (40 mg) and injectable solution (10 mg). After two weeks of treatment with 40 mg ketanserin tablets further 18 blood samples for analysis were collected under steady-state conditions. Plasma levels were measured by HPLC. The absolute bioavailability of ketanserin tablets was 52.7%; their relative bioavailability compared to a solution containing an equal quantity of active compound was 85.5%. Therefore, the low absolute bioavailability of ketanserin cannot be attributed to the formulation. The active compound was rapidly liberated from the tablet, reaching a peak of 103.8 ng/ml after 0.97 h. Individual plasma level-time curves were fitted to an open three compartment model and a half-life of 17.7±7.26 h was calculated for the terminal elimination phase. An average terminal elimination half-life of 15.4±4.2 ng/ml was found after administration of the ketanserin solution. Multiple dosing with 40 mg tablets b.d.s. resulted in an AUC over one dosing interval at steady-state of 666±201 ng × h/ml. The AUC extrapolated to infinity was 1200±405 ng × h/ml for the last tablet. This is 1.8-times the AUC in one dosing interval, and 2.3-times the AUC of a single dose. Under steady-state conditions, the mean peak plasma level was 155.1 ng/ml (1.08 h after dosing) and the terminal half-life was 19.1±5.1 h. For the metabolite ketanserinol terminal half-lives of 21.4 h after a single tablet and 31.0 h after discontinuation of multiple dosing were calculated. Compared to the parent compound there was much more marked accumulation of ketanserinol. Despite moderate accumulation and prolongation of the terminal half-life of ketanserin under steady-state conditions, dosage adjustment is not required in elderly people. First-pass metabolism and bioavailability remained in the range found in previous studies of ketanserin in young subjects.
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  • 29
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    European journal of clinical pharmacology 28 (1985), S. 429-431 
    ISSN: 1432-1041
    Keywords: theophylline ; asthma ; personality measures ; pharmacokinetics ; volunteers ; patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Thirteen volunteers received an iv dose of theophylline followed by blood sampling for 8 h to calculate pharmacokinetic parameters. Ten patients with asthma undergoing chronic dosing with slow release aminophylline underwent 12 h of blood sampling to calculate theophylline clearance. Both groups completed an Eysenck Personality Inventory (EPI) from which was derived scores for neuroticism (N) and extroversion (E). Using multiple regression analysis no independent effect of either N or E score on theophylline clearance or half-life could be demonstrated.
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  • 30
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    European journal of clinical pharmacology 28 (1985), S. 433-437 
    ISSN: 1432-1041
    Keywords: isofezolac ; probenecid ; pharmacokinetics ; anti-inflammatory drug ; drug interaction ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The interaction between isofezolac and probenecid has been studied with the aid of a specific HPLC assay for isofezolac in plasma and urine. 8 healthy adult volunteers received a single 40 mg oral dose of isofezolac before and after 3 days of loading with 0.5 g probenecid t.i.d. There was an increase in the maximum plasma isofezolac concentration from 2.44 to 3.38 µg · ml−1 when probenecid was given. The AUC of isofezolac in plasma increased from 6.73 to 11.28 µg · h · ml−1. After the last dose in a 7 day treatment with 40 mg isofezolac t.i.d., there was an increase in the maximum plasma isofezolac level from 2.84 to 4.96 µg · ml−1 when probenecid was given. The rate of absorption of isofezolac was not affected. An increase in the AUC of isofezolac in plasma was observed from 11.74 to 26.34 µg · h · ml−1. The major effect of probenecid on isofezolac metabolism was a 50% reduction in total isofezolac (free+conjugates) excreted inurine. Because of this interaction, patients given isofezolac combined with probenecid will have a higher steady-state plasma level of isofezolac than when probenecid is not administered.
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  • 31
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    European journal of clinical pharmacology 28 (1985), S. 439-445 
    ISSN: 1432-1041
    Keywords: acetohydroxamic acid ; staghorn renal calculi ; pharmacokinetics ; 14C-labeled drug ; acetamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Acetohydroxamic acid (AHA), a bacterial urease inhibitor, has been recently approved by the United States Food and Drug Administration as a potential drug for the successful treatment of patients with infection induced staghorn renal calculi. The present study was designed to evaluate the disposition of 14C-AHA following oral administration to patients. The results of the study, while in a limited number of patients, indicate that upon oral administration, AHA is very rapidly absorbed from the gastrointestinal tract. Evaluation of urinary excretion data suggests that patients with compromised renal function have low recoveries of AHA in the urine. These data are supported by a strong linear correlation between creatinine clearance and AHA elimination. Acetamide and CO2 are identified as the two major metabolites of AHA in man. CO2 is eliminated in the breath and accounts for 20–45% of the administered dose, while acetamide is eliminated in the urine and accounts for only 9–14% of the administered dose. The remaining dose is eliminated as intact AHA in the urine (19–48%). Saliva concentrations of total radioactivity depict a strong positive correlation with their respective plasma concentrations. Parameter estimates from 14CO2 concentrations in breath as a function of time data closely correspond to the pharmacokinetic parameters of AHA in patients indicating that CO2 may be a primary metabolite derived directly from AHA rather than a secondary metabolite formed by the metabolism of an intermediate product. Upon multiple dose administration of AHA, there is the potential for significant accumulation of acetamide due to its relatively long half-life.
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  • 32
    ISSN: 1432-1041
    Keywords: methotrexate ; osteosarcoma ; high parenteral dose ; pharmacokinetics ; drug monitoring ; computer prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Methotrexate (MTX) in serum was measured by RIA in 12 cancer patients receiving high doses of MTX (2 to 8 g/m2) in 6 hour infusions 69 treatments were studied. The peak serum level was proportional to the dose administered and was always greater than 10−4 M. 2 elimination phases were seen: the first had a mean half-life of 2.36 h and the second a mean half-life of 16.14 h. 24 hours after beginning the infusions there were very large variations in individual serum concentrations of MTX, from 2.4 10−6 M to 1.9 10−5 M by 24 h after 8 g/m2. To control these variations, a mathematical model for prediction of the individual pharmacokinetic pattern of a 6 hour-infusion of high-dose MTX by kinetic analysis of a low-test dose is proposed. A program was created for an Apple III computer using toxic and therapeutic serum levels of MTX selected by the clinician. The computer program is adaptable to any infused substance for variable infusion times, thus introducing new advances over existing methods.
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  • 33
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    European journal of clinical pharmacology 28 (1985), S. 469-471 
    ISSN: 1432-1041
    Keywords: interferon ; cancer patients ; recombinant leukocyte A interferon ; rIFN-αA ; i.v.-/i.m. administration ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Interferon is currently being evaluated for the treatment of disseminated cancer and viral diseases. Alpha interferons have shown to be effective in the treatment of a number of malignancies. Recombinant leukocyte A interferon (rIFN-αA) is an alpha interferon produced by recombinant DNA techniques. A kinetic evaluation of rIFN-αA following intravenous and intramuscular administration has not been adequately defined. The present study was designed to evaluate the kinetics of rIFN-αA following intravenous and intramuscular administration of 3, 9 or 18×106 units to patients with disseminated cancer. A preliminary report of this study was presented at the meeting of the American Society for Clinical Pharmacology and Therapeutics in San Diego, March 1983 (1).
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  • 34
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    European journal of clinical pharmacology 28 (1985), S. 543-552 
    ISSN: 1432-1041
    Keywords: thiopentone ; anaesthesia ; intravenous anaesthesia ; multi-stage infusion ; exponential infusions ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Several multi-stage infusion regimens and a computer controlled exponentially decreasing infusion regimen were evaluated in twelve patients undergoing head and neck surgery or neurosurgery. Thiopentone dosage was based on the mean of pharmacokinetic parameter values from the literature and adjusted for each patient's lean body mass in order to rapidly achieve a predetermined plasma thiopentone concentration of 15 or 20 µg/ml in the period following the initial bolus dose to induce anaesthesia. Anaesthesia was satisfactory in all cases. Plasma thiopentone concentrations were maintained between 10–20 µg/ml during infusion in the five patients who received either a four or five stage infusion and in the six patients who received the exponential infusion, but not in the single patient who received a two-stage infusion. The mean recovery time was 111 min. The plasma concentrations of total and unbound thiopentone at awakening showed little intersubject variability, despite considerable differences in total dose and duration of infusion, suggesting the absence of acute tolerance to the drug. Plasma clearance of total thiopentone correlated strongly with calculated lean body mass and to a lesser extent with total body weight suggesting that lean body mass, in particular, should be an accurate predictor of thiopentone maintenance dose requirements. This study shows that it is feasible to use thiopentone as a primary anaesthetic agent during surgery by administering the drug either as an exponentially decreasing infusion or as an infusion comprising 4 or 5 stepwise decreasing rates.
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  • 35
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    European journal of clinical pharmacology 28 (1985), S. 581-583 
    ISSN: 1432-1041
    Keywords: piretanide ; liver cirrhosis ; ascites ; bioavailability ; pharmacokinetics ; diuretic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of piretanide, a new loop diuretic, were studied in seven patients with severe liver disease before and after resolution of ascites. The time to maximum concentration was significantly prolonged by the presence of ascites. Tmax after relief of ascites was similar to that seen for normal volunteers. Area under the curves, bioavailability, volumes of distribution and elimination half-lives did not change after resolution of the ascites: two patients in whom diuretic resistant ascites occurred showed similar pharmacokinetics to that of the diuretic responders. Reduced responsiveness to piretanide therapy in patients with gross ascites does not appear to be the result of decreased bioavailability.
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  • 36
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    European journal of clinical pharmacology 28 (1985), S. 601-605 
    ISSN: 1432-1041
    Keywords: smectite ; phenylbutazone ; diazepam ; pharmacokinetics ; drug interactions ; drug adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The interaction of phenylbutazone and diazepam with smectite were studied in in-vivo and in-vitro. The kinetics of both drugs were investigated in healthy subjects after oral administration as monotherapy or in association with smectite. Smectite did not substantially alter the kinetics of phenylbutazone, whereas the peak plasma concentration of diazepam was reduced to 91%, and the time of peak concentration was prolonged by 153% of the control values. The in-vitro investigations were conducted at pH 5.5 and 8 and showed that there was no interaction between phenylbutazone and smectite, but that it adsorbed diazepam. The findings suggest that smectite delays the absorption of basic drugs and does not alter the absorption kinetics of acidic drugs.
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  • 37
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    European journal of clinical pharmacology 28 (1985), S. 689-692 
    ISSN: 1432-1041
    Keywords: isoxicam ; piroxicam ; pharmacokinetics ; elderly ; anti-inflammatory drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of isoxicam and piroxicam were compared in 12 young adults (〈40 years) and 12 elderly subjects (〉65 years). After a single oral dose of 200 mg isoxicam or 20 mg piroxicam blood samples were taken for 168 h and the plasma drug concentrations determined by HPLC. The elimination half life of piroxicam for the adults was 57.1±16.4 h (mean ± SD; harmonic mean 52.9 h) and for the elderly subjects was 57.8±22.1 h (harmonic mean 52.1 h). The corresponding values after isoxicam were 34.3±13.6 h (harmonic mean 31.6) for the adults and 39.1±22.7 h (harmonic mean 33.5) for the elderly subjects. Similarly no differences were noted in either the AUC0-∞ after piroxicam (adults 154.1±52.2 µg·h/ml, elderly 163.6±99.1 µg·h/ml) and isoxicam (adults 642.7±241.9 µg·h/ml, elderly 787.9±613.1 µg·h/ml) or the apparent oral clearance of piroxicam (adults 2.39±0.80 ml/min, elderly 2.51±0.90 ml/min) and isoxicam (adults 5.84±2.04 ml/min, elderly 5.59±2.12 ml/min). One adult and two elderly subjects exhibited slower elimination of both medicines than the remainder of each group. However determination of the oxidation phenotype using sparteine metabolism showed that this was not a likely determinant of the reduced clearance.
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  • 38
    ISSN: 1432-1041
    Keywords: glibenclamide ; glipizide ; pharmacokinetics ; metabolic effects ; Type 2 diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Fifteen Type 2 diabetics were treated for 4-week periods with once daily (10 mg) glibenclamide, glipizide and placebo according to a double-blind cross-over protocol. Post-dose glipizide concentrations were three times higher than those of glibenclamide, due to the incomplete bioavailability of the latter. On the other hand, pre-dose drug levels were similar, as an expression of the slower absorption and/or elimination of glibenclamide. Both active treatments reduced postprandial blood glucose concentrations and 24-hour urinary glucose excretion to a similar degree, but fasting blood glucose concentrations were slightly lower during glibenclamide treatment. Both active treatments enhanced fasting and postprandial insulin and C-peptide concentrations, the C-peptide response being greater after glipizide than after glibenclamide. Plasma glucagon and GIP concentrations were not significantly affected. Insulin sensitivity was increased by glibenclamide but not by glipizide. Neither therapy affected insulin binding to erythrocytes. It appears that both glibenclamide and glipizide improved glucose metabolism by sustained stimulation of insulin secretion, which was most pronounced with glipizide. Only glibenclamide improved insulin sensitivity and was slightly more active than glipizide on fasting blood glucose levels. The differences may be consequences of the pharmacokinetics, but differences in pharmacodynamics cannot be excluded.
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  • 39
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    European journal of clinical pharmacology 28 (1985), S. 721-722 
    ISSN: 1432-1041
    Keywords: chloroquine ; rheumatoid disease ; desethylchloroquine ; capacity limitation ; pharmacokinetics ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of chloroquine and its major metabolite desethylchloroquine were studied in patients with rheumatoid disease after single oral doses of chloroquine phosphate corresponding to 150 and 300 mg chloroquine base. The findings strengthen the previous finding that the disposition of chloroquine involves rate limiting steps.
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  • 40
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    European journal of clinical pharmacology 28 (1985), S. 41-43 
    ISSN: 1432-1041
    Keywords: disopyramide ; atenolol ; pharmacokinetics ; drug interaction ; ischaemic heart disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of atenolol on the total elimination of disopyramide and its main dealkylated metabolite was studied in 6 patients and 3 volunteers. During administration of 50 mg atenolol b.i.d. the clearance of disopyramide decreased significantly (p〈0.02) from 1.90±0.71 (X±SD) to 1.59±0.68 ml/kg/min, while its half-life, concentration of the metabolite, and the volume of distribution remained unchanged. The reduction in the clearance of disopyramide by atenolol might contribute to the alleged pharmacodynamic interaction between disopyramide and β-blocking drugs.
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  • 41
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    European journal of clinical pharmacology 28 (1985), S. 73-78 
    ISSN: 1432-1041
    Keywords: procyclidine ; Kemadrin ; pharmacokinetics ; pharmacodynamics ; humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and pharmacodynamics of procyclidine (10 mg) after oral and intravenous administration were studied in six healthy volunteers. Treatment order was randomised and the study was placebo-controlled and conducted blind. After oral dosing the mean peak plasma concentration was 116 ng/ml and mean bioavailability was 75%. After both oral and intravenous dosing the mean values for the volume of distribution, total body clearance and plasma elimination half-life of procyclidine were in the order of 1 l/kg, 68 ml/min and 12 h respectively. Autonomic effects were maximal within 0.5 h of intravenous administration and at about 1–2 h after oral dosing. Significant effects on pupil diameter, visual near point, salivary secretion and heart rate occurred after intravenous treatment and similar but less marked effects occurred after the oral dose. Significant autonomic effects were still detectable 12 h after both forms of treatment.
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  • 42
    ISSN: 1432-1041
    Keywords: sulphinpyrazone ; metabolism ; single dose ; chronic treatment ; pharmacokinetics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of sulphinpyrazone and its major metabolites (sulfide, sulfone, p-hydroxysulfone and p-hydroxy-sulphinpyrazone) were investigated in 9 volunteers after a single oral dose as well as after chronic treatment for 23 days. Chronic administration of sulphinpyrazone, in comparison with a single oral dose, led to significant changes in plasma AUC (115.86 to 42.90 mg/l·h), in renal clearance (1.06 to 1.80l/h), in hepatic intrinsic clearance (319.0 to 598.0l/h), and in the unbound fraction in plasma 1.15 to 1.69%) and in tissue (2.73 to 1.31%). The volume of distribution changed from 20.24 to 52.041. The steady state concentrations predicted from the single dose were significantly higher than the values found after chronic treatment. The results suggest that sulphinpyrazone induces its own metabolism. The metabolism of the sulfone, p-hydroxysulfone and the p-hydroxy-sulphinpyrazone to further degradation products was also induced. Chronic treatment with sulphinpyrazone reduced the plasma AUC of the sulfide and caused a decrease in its elimination half-life (20.9 to 14.3 h). Since considerable amounts of the sulfide are formed in the G.I. tract, it is suggested that besides the induction of metabolism, bacteria which reduce sulphinpyrazone to the sulfide may also be responsible for the observed pharmacokinetic changes.
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  • 43
    ISSN: 1432-1041
    Keywords: moclobemide ; Ro 11-1163 ; pharmacokinetics ; bioavailability ; MAO activity in platelets ; monoamine metabolites in urine ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma concentrations of the MAO-inhibitor moclobemide (Ro 11-1163) were determined in six healthy male subjects after oral (tablets) administration. Effects on MAO activity in platelets and excretion of monoamine metabolites in urine were investigated. The design of the study was a double-blind cross-over study with single oral doses of placebo, 50, 100 and 200 mg of moclobemide. The elimination profile of the drug showed that the half life of the unchanged drug ranged between 1 and 2 h except in one subject with a half-life of about 4 h. The mean bioavailability calculated using flow model concepts was F=0.43 after 50 mg, F=0.47 after 100 mg and F=0.59 after 200 mg. The outlier with a t1/2 of 4 h was found to have a bioavailability of more than 0.80 after all 3 doses. The slightly increasing bioavailability with higher doses was interpreted as evidence of saturable hepatic first-pass elimination of the drug. MAO activity in platelets was measured before and 2, 6 and 24 h after drug administration. No inhibition of platelet MAO was obtained at any point in time or dose level, as to be expected since moclobemide preferentially inhibits MAO A. Urine excretion of the monoamine metabolites homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC), 3-methoxy-4-hydroxy-phenylglycol (MOPEG) and 5-hydroxyindoleacetic acid (5-HIAA) was followed during 48 h after placebo, 50 and 200 mg of moclobemide. Time but not dose contributed significantly to the variability in excretion of the monoamine metabolites. An apparent reduction of HVA and DOPAC levels was obtained in the early phase after the administration of 200 mg of moclobemide. In 1 subject with a mild drug reaction a pronounced decrease in the levels of all the metabolites was obtained. In the other 5 subjects, the compound was very well tolerated with a few reported side-effects like increased activity, somnolence or sweatings. There was a slight but significant increase in blood pressure following 50 and 100 mg but not 200 mg of moclobemide.
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  • 44
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    European journal of clinical pharmacology 29 (1985), S. 215-219 
    ISSN: 1432-1041
    Keywords: penbutolol ; renal impairment ; beta-adrenoceptor blocking agents ; metabolism ; hypertension ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of penbutolol, its 4-hydroxylated metabolite and of their conjugates was studied in hypertensive patients with various degrees of renal impairment. A single oral dose of penbutolol 40 mg, was rapidly absorbed after a lag-time of 0.34 h. Its plasma concentration reached a maximum after 0.84 h and then declined bi-exponentially, with an apparent elimination half-life of 21.8 h. The hydroxylation of penbutolol was negligible and conjugation was of major importance for its elimination. Consequently, the kinetics of unchanged penbutolol were not altered by renal impairment. The 48 h-urinary excretion of penbutolol and its metabolites reached 13–14% of the administered dose, which is consistent with extensive metabolism of the drug. After treatment for 30 days with penbutolol 40 mg/d there was no accumulation of the parent drug but the concentration of its conjugates was increased. It is concluded that the dose of penbutolol need not be changed in patients with mild renal insufficiency, 4-hydroxypenbutolol is unlikely to participate in the anti-hypertensive effect of the drug, due to its low concentrations, and biotransformation of penbutolol may be enhanced during chronic treatment.
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  • 45
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    European journal of clinical pharmacology 29 (1985), S. 221-224 
    ISSN: 1432-1041
    Keywords: fenfluramine ; norfenfluramine ; isomers ; pharmacokinetics ; healthy volunteers ; chronic treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of accumulation and elimination of d- and l-fenfluramine (F) and norfenfluramine (NF) have been studied in 8 young healthy volunteers given daily doses of 60 mg of sugar-coated tablets of 20 mg dl-F hydrochloride (dl-F) t.i.d. and capsules of 15 mg d-F hydrochloride (d-F) b.i.d. for 15 days. Repeated doses of d-F plus l-F gave the same values for the parameters measured as did d-F administered alone. Steady-state concentrations of all compounds were achieved within 4–8 days. The predicted mean steady-state concentrations of d-F and elimination half-lives calculated from the results of a previous single dose study were similar to those measured at steady state in this study, confirming the lack of effect of the drug on hepatic microsomal enzymes and on kinetics after repeated dosing. d-NF concentrations were approximately half those of the parent drug and the half-life was almost twice as long. Steady state concentrations both of L-f and l-NF were consistently about 40–50% higher than of the d-isomers and there was a comparable in the half-life.
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  • 46
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    European journal of clinical pharmacology 29 (1985), S. 235-239 
    ISSN: 1432-1041
    Keywords: amoxycillin ; clavulanic acid ; pharmacokinetics ; side-effects ; paediatric formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A combination of amoxycillin and clavulanic acid 4:1 was administered to 35 children (aged 2 to 10 years) with infections. The combination was administered orally as a suspension, every 8 h for 5 to 7 days. Sixteen children (aged 2 to 5 years), received 125 mg amoxycillin and 31.25 mg clavulanic acid, and 19 (6 to 10 years) received 250 mg amoxycillin and 62.5 mg clavulanic acid per dose. Following the first dose serum concentrations of amoxycillin and clavulanic acid were determined by microbiological assay. In the younger group receiving the lower dosage (mean: amoxycillin 9.11 mg/kg and clavulanic acid 2.34 mg/kg), the mean peak concentration of amoxycillin was 3.5 mg/l and of clavulanic acid 1.2 mg/l, occurring 1.32 h and 1.39 h, respectively, after administration. In the older group receiving the higher dosage (mean: amoxycillin 12.35 mg/kg and clavulanic acid 3.14 mg/kg) the mean peak serum level of amoxycillin was 4.0 mg/l and of clavulanic acid 1.3 mg/l, occurring 1.43 h and 1.23 h, respectively, after administration. The higher dose per kilogram body weight resulted in a higher peak serum concentration both of amoxycillin and clavulanic acid. The formulation was well tolerated by all the children and no serious side-effects were recorded. Treatment was considered clinically effective in all cases.
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  • 47
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    European journal of clinical pharmacology 29 (1985), S. 323-329 
    ISSN: 1432-1041
    Keywords: lignocaine ; pharmacokinetics ; proteinbinding ; indocyanine green ; ageing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Single dose studies were performed in six young and six elderly nonsmokers using lignocaine as a model drug with high intrinsic clearance. Subjects received lignocaine 250 mg orally and 50 mg intravenously in random order and drug concentrations in blood and plasma were measured for up to 8 h after dose. Protein binding was estimated at 37 °C by equilibrium dialysis. Indocyanine green kinetics were also calculated in each individual following 0.15 mg/kg intravenously. Bioavailability of lignocaine was greater in the elderly but there was no apparent difference in the rate of absorption. Intrinsic clearance of lignocaine was lower in the aged. Elimination half-life was longer in the elderly but there was no significant difference in apparent volume of distribution or systemic clearance of lignocaine. Plasma clearance of indocyanine green showed no correlation with systemic lignocaine clearance and was lower in the aged subjects. Blood/plasma lignocaine ratio was less than unity in both groups. Binding of lignocaine to plasma proteins showed concentration-dependence and was higher in the geriatric group. Maximum binding capacity of lignocaine was greater in the elderly but the binding affinity did not significantly change with age. Greater oral bioavailability of drugs like lignocaine may produce higher plasma concentrations in the elderly. Unlike indocyanine green, the systemic clearance of lignocaine was unaltered by age in this group of non-smokers. The protein-binding of lignocaine, like many other basic drugs, is increased in elderly subjects.
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  • 48
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    European journal of clinical pharmacology 29 (1985), S. 467-469 
    ISSN: 1432-1041
    Keywords: baclofen ; stroke ; elderly patients ; pharmacokinetics ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A double blind crossover trial of baclofen against placebo in elderly stroke patients was discontinued because the drug produced an unacceptably high level of drowsiness. In a subsequent study baclofen 10 mg was given orally to 12 elderly stroke patients, and drug concentrations measured from a series of plasma samples. A group of healthy subjects given the same dose in a previous study were used as controls. Elderly patients took longer to achieve peak plasma baclofen concentrations, but healthy controls had higher peak values and eliminated the drug more rapidly; areas under the curve were similar in the two groups. Simulations based on mean data suggest that increased drowsiness in the elderly was probably not due to changes in the drug's pharmacokinetic behaviour.
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  • 49
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    European journal of clinical pharmacology 29 (1985), S. 461-465 
    ISSN: 1432-1041
    Keywords: carteolol ; chronic renal failure ; pharmacokinetics ; dosage adjustment ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma levels and urinary excretion of carteolol and its main metabolites 8-hydroxycarteolol and carteolol glucuronide were investigated in 6 healthy subjects and 9 patients with varying degrees of renal impairment following a single oral dose of 30 mg carteolol hydrochloride. In healthy subjects the half-life of carteolol was 7.1 h. 63% of the administered dose was recovered unchanged in urine, and in all 84% was excreted by the kidneys. The renal clearance of carteolol was 255 ml/min. In chronic renal failure (CRF) the terminal half-life was increased to a maximum of 41 h. Both the elimination rate constant and renal clearance were closely related to the creatinine clearance. In CRF the recovery of carteolol and its metabolites from urine was considerably reduced, suggesting that another pathway of drug elimination becomes relevant in renal disease. To avoid an increase in side-effects due to drug accumulation, the dosage of carteolol should be adjusted in relation to the reduction in creatinine clearance. The maintenance dose should be reduced to a half in patients with a creatinine clearance below 40 ml/min and above 10 ml/min. In those with a creatinine clearance of 10 ml/min or less, the dose should be reduced to 1/4.
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  • 50
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    European journal of clinical pharmacology 29 (1985), S. 477-481 
    ISSN: 1432-1041
    Keywords: budesonide ; glucocorticoid ; nasal administration ; pharmacokinetics ; bioavailability ; systemic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Budesonide, a topically potent glucocorticoid, was administered to 4 healthy volunteers by i.v. infusion and by nasal instillation of 100 µg tritium-labelled drug. Plasma was analyzed by liquid chromatography plus scintillation counting of collected fractions. After i.v. administration the plasma clearance was 0.92 l/min and the apparent volume of distribution was 2.8 l/kg. After nasal administration, the time to reach the peak plasma level was approximately 30 min, and the systemic availability was 102%. Budesonide had marginal effects on plasma cortisol and white blood cell counts either after i.v. or nasal administration. Thus, nasally instilled budesonide in solution is rapidly and completely absorbed from the nasal mucosa. The systemic effects after this clinically recommended nasal dose were negligible.
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  • 51
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    European journal of clinical pharmacology 29 (1985), S. 503-509 
    ISSN: 1432-1041
    Keywords: deconvolution ; haemodialysis ; cefsulodin ; extracorporal drug removal ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A novel approach to the evaluation of the kinetics of drug removal by an extracorporal device (ECD), e.g., haemodialysis, haemofiltration, and haemoperfusion, is presented. The rate and extent of extracorporal drug removal (ECR) are determined by deconvolution. The proposed method is model independent in the sense that no specific models of corporal or extracorporal disposition are required. The estimation of various derived functions and parameters useful for describing ECR such as clearance and fractional drug removal are facilitated by the technique. The kinetics of cefsulodin elimination by haemodialysis in 3 patients were evaluated using the deconvolution approach. The results indicated that cefsulodin was dialyzable with ∼50% of the drug in the body removed by haemodialysis over 3–4 h.
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  • 52
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    European journal of clinical pharmacology 28 (1985), S. 405-410 
    ISSN: 1432-1041
    Keywords: verapamil ; renal failure ; norverapamil ; pharmacokinetics ; haemodialysis ; ECG ; blood pressure ; heart rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of verapamil was studied in patients with end-stage chronic renal failure and in normal subjects after i.v. injection of 3 mg and a single oral dose of 80 mg. Plasma levels of verapamil and its active metabolite norverapamil were measured by HPLC. After i.v. injection, the terminal phase half-life and total plasma clearance of verapamil in both groups were similar. Haemodialysis did not change the time course of plasma verapamil levels after i.v. administration. After a single oral dose, the plasma levels of verapamil and norverapamil in both groups of subjects were similar. Subsequently, normal volunteers and patients with renal failure were treated for 5 days with oral verapamil 80 mg t.d.s. There was no difference between the 2 groups of subjects in the trough and peak levels of verapamil or of norverapamil. Intravenous and oral administration of the calcium channel blocking agent had similar effects on blood pressure, heart rate and the PR-interval in the electrocardiogram in both groups. The study demonstrated that the disposition of verapamil was similar in normal subjects and in patients with renal failure.
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  • 53
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    European journal of clinical pharmacology 28 (1985), S. 425-428 
    ISSN: 1432-1041
    Keywords: caffeine ; oral contraceptives ; pharmacokinetics ; elimination half-life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of chronic (〉3 months) administration of low-dose oestrogen-containing (〈50 µg oestrogen) oral contraceptives (OCS) on the pharmacokinetics of caffeine has been examined in a treated females matched with 9 non-smoking, drug-free, healthy control females of similar age, weight and ethnic origin. Each subject received 162 mg caffeine base orally after an overnight fast. OCS subjects had a prolonged elimination half-life of caffeine, (mean 7.88 h vs 5.37 h in the controls). This was the result of marked impairment of the plasma clearance of caffeine (1.05 vs 1.75 ml/min/kg, respectively) with no change in apparent volume of distribution (0.685 in OCS vs 0.750 l/kg in the control group). The absorption parameters determined were peak plasma caffeine concentration (3.99 vs 4.09 µg/ml) and time to peak concentration after drug administration (1.52 vs 0.79), which was moderately prolonged in OCS users. Thus, caffeine clearance, previously reported to be a specific marker of cytochrome P-448 activity in man, is decreased by chronic OCS use. This suggests that OCS may cause significant impairment of this enzyme activity as assessed in vivo. With chronic caffeine consumption, OCS users are predicted to have an increased steady-state plasma caffeine concentration as compared to non-OCS users.
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  • 54
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    European journal of clinical pharmacology 28 (1985), S. 641-647 
    ISSN: 1432-1041
    Keywords: Femoxetine ; alcohol interaction ; psychomotor performance ; pharmacokinetics ; amitriptyline ; plasma 5HT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects on human psychomotor performance of femoxetine (FEMO), a 5-hydroxytryptamine-selective antidepressant, alone and in combination with alcohol (EtOH) were compared with those of amitriptyline (AMI) and placebo in a controlled double-blind crossover trial in 11 student volunteers. Objective measurements (body sway, choice reaction, flicker fusion, tracking, nystagmus, digit symbol substitution, backwards recall) and subjective self-assessment (visual analogue scales, reporting of side-effects) were done after single doses of FEMO, AMI and placebo, and subacute administration of FEMO and placebo. Single doses of 200 mg FEMO did not impair psychomotor performance, but 50 mg AMI did so in several respects. AMI but not FEMO increased the objective and subjective effects of EtOH. After FEMO 600 mg/d for 10 days almost no objective difference from placebo was noted, although mild sedation at home was reported as a side-effect. FEMO either did not increase or slightly decreased the effect of EtOH on reactive and co-ordination skills. The plasma concentrations of FEMO varied widely from 0 to 156 ng/ml, as in previous clinical trials but reduced a blood 5-hydroxytryptamine concentration in each subject indicating an effect of FEMO on serotoninergic mechanisms.
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  • 55
    ISSN: 1432-1041
    Keywords: omeprazole ; renal failure ; gastric secretion ; pharmacokinetics ; haemodialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The inhibitory effect of omeprazole on gastric acid secretion was tested in a group of patients on haemodialysis for chronic renal failure. Single 30 mg doses almost totally inhibited basal acid output on both dialysis and non-dialysis days. Plateau acid output was reduced by a mean of 77% and 90% on non-dialysis and dialysis days respectively. The absorption and pharmacokinetic profile of omeprazole were not affected by dialysis. Omeprazole was not recoverable from dialysis fluid. It is concluded that omeprazole is a potent inhibitor of gastric acid secretion in patients with chronic renal failure, and its effect is not influenced by haemodialysis.
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  • 56
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    European journal of clinical pharmacology 28 (1985), S. 45-51 
    ISSN: 1432-1041
    Keywords: disopyramide ; myocardial infarction ; antiarrhythmic agent ; pharmacokinetics ; protein binding ; intravenous administration ; oral administration ; gastro-intestinal absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To study the effects of acute myocardial infarction on the pharmacokinetics of disopyramide a single oral dose of disopyramide base (200 mg) was administered to 6 patients with myocardial infarction both in the acute (Study I) and recovery (Study II) phases. An intravenous tracer dose of14C-disopyramide (2.5 µg/0.3 mg) was given simultaneously with the oral dose. On the basis of the intravenous tracer data, the volume of distribution, binding to plasma proteins, total plasma clearance, renal clearance and elimination half-life of disopyramide and mono-N-dealkyl disopyramide were the same in Studies I and II. The peak serum concentrations of disopyramide after oral dosing in Studies I and II were 2.6±1.2 (SEM) and 6.4±1.9 µg/ml, respectively (p〈0.05), the peak times 3.29±1.22 and 1.21±0.39 h (N.S.) and the AUCINF 38.0±7.7 and 60.7±9.9 µg·h·ml−1 (p〈0.05). The recovery of disopyramide in urine over 3 days averaged 46% and 47% of dose, and that of mono-N-dealkyl disopyramide 22% and 16% of the dose, respectively. Thus, the gastrointestinal absorption of disopyramide was disturbed, resulting in low plasma concentrations after oral dosing, whereas the elimination of disopyramide was unaltered in the acute phase of myocardial infarction.
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  • 57
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    European journal of clinical pharmacology 28 (1985), S. 61-66 
    ISSN: 1432-1041
    Keywords: amiloride ; kidney function ; Na+ ; K+ ; Ca++ ; Mg++ excretion ; renal amiloride clearance ; chronic renal failure ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of a single oral dose of 10 mg amiloride was studied on urinary excretion of Na+, K+, Ca++ and Mg++ in healthy subjects and in patients with varying degrees of renal impairment. Amiloride produced a moderate diuresis and sodium excretion, and a slight calciuresis. Urinary excretion of potassium was significantly reduced as compared to the controls. Despite its diuretic and natriuretic effects, amiloride did not change the excretion of Mg++ as compared to the pretreatment period. When the creatinine clearance was below 50 ml/min, the net excretion of Na+ and Ca++ was drastically reduced. However, K+ retention and neutrality of Mg++ excretion were maintained down to end-stage renal disease. In the healthy volunteers the mean elimination half-life of amiloride was 20 h, and it rose to about 100 h in end-stage renal disease. This was because about 3/4 of native amiloride was eliminated through the kidney. Nonrenal elimination of amiloride was calculated to amount to only 1/4 of the total elimination. Therefore, the antikaliuretic amiloride is a valuable comedication in subjects with normal kidney function to prevent K+ and Mg++ loss. However, its use is hazardous if plasma creatinine is raised.
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  • 58
    ISSN: 1432-1041
    Keywords: metaclazepam ; benzodiazepines ; (KC-2547) ; N-desmethyl-methaclazepam KC-3755) ; pharmacokinetics ; old and young volunteers ; side-effects ; age effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A single-centre, open, Phase I-study comparison of the pharmacokinetics of a single dose of metaclazepam 10 mg, a new 1,4-benzodiazepine has been done in 10 older and 20 younger volunteers. No important age-related effect was found on the kinetics of metaclazepam or its N-desmethyl derivative, the principal metabolite in man.
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  • 59
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    European journal of clinical pharmacology 29 (1985), S. 255-256 
    ISSN: 1432-1041
    Keywords: gentamicin ; malnutrition ; protein-energy deficiency ; malnourished children ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of i.m. gentamicin was the same in malnourished (n=6) and normal (n=4) children.
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  • 60
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    European journal of clinical pharmacology 28 (1985), S. 231-233 
    ISSN: 1432-1041
    Keywords: erythromycin ; pharmacokinetics ; steady-state ; food effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The steady state absorption of erythromycin from enteric-coated pellets of erythromycin base was compared with that from enteric-coated tablets in a randomized, two-way cross-over study in 24 healthy adult volunteers. A higher mean individual peak concentration (p〈0.01), and a greater mean area under the serum concentration-time (0–8 h) curve (AUC,p〈0.01) was produced by the enteric-coated pellets, when the preparations were administered 1 hour before breakfast. No significant differences in the kinetic parameters between the two preparations were observed when they were taken during a non-standardized breakfast, as concomitant food intake was found to reduce both the peak levels and the AUC-values (p〈0.01) produced by the pelleted preparation.
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  • 61
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    European journal of clinical pharmacology 28 (1985), S. 225-227 
    ISSN: 1432-1041
    Keywords: theophylline ; absorption ; food intake ; aqueous solution ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of food on the rate and extent of absorption of theophylline was studied in healthy adults given a single dose of theophylline (aqueous solution of choline theophyllinate containing 270 mg of theophylline) in the evening either on an empty stomach or together with supper. Food appeared to decrease the absorption rate of theophylline significantly, tmax being prolonged from 1.34 h (mean) to 4.40 h and cmax decreased from 7.82 mg·l−1 to 5.47 mg·l−1. The area under the plasma concentration-time curve (AUC) after drug intake with supper was slightly but not significantly smaller, indicating that theophylline (as a solution of choline theophyllinate) can be taken together with food without substantial loss of the quantity of drug absorbed. The elimination rate was not influenced by concomitant intake of supper.
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  • 62
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    European journal of clinical pharmacology 28 (1985), S. 305-309 
    ISSN: 1432-1041
    Keywords: piroxicam ; pharmacokinetics ; geriatrics ; renal insufficiency ; drug safety ; non-steroidal anti-inflammatory drugs ; osteoarthritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Age-dependent changes in pharmacokinetics are considered a possible factor contributing to a higher risk of side-effects from drug treatment in the elderly. However, very little is known about the kinetics and metabolism of most NSAI agents in geriatric subjects. In a prospective age-comparison study, the single dose and steady-state pharmacokinetics of piroxicam 20 mg once daily were determined in 44 subjects ranging in age from 30 to 80 years. Plasma concentrations, elimination half-life, AUC, and volume of distribution were not influenced by age or sex and were in agreement with previously reported results in young adults. Pharmacokinetic parameters in 18 patients with evidence of mild or moderate renal impairment at study entry were not different from those in patients without impairment. Based on this and other studies, elderly patients receiving the recommended dose of piroxicam are not exposed to undue risk related to pharmacokinetic considerations.
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  • 63
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    European journal of clinical pharmacology 28 (1985), S. 453-456 
    ISSN: 1432-1041
    Keywords: zimeldine ; norzimelidine ; pharmacokinetics ; renal insufficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of zimeldine (Z) and its demethylated metabolite, norzimelidine (NZ), were determined after administration of a single 200 mg oral dose of Z to 6 healthy volunteers (Group I), and to patients with mild (Group II) and severe renal failure (Group III). Z and NZ concentrations were assayed by HPLC in serial plasma and urine samples over 6 days following the dose. In Group I Z was rapidly absorbed and metabolized into NZ, and then the plasma concentrations declined with apparent elimination half-lives of 8.4 h and 24.9 h for Z and NZ respectively, whilst the renal clearance of both compounds was low, Z 15.7 ml/min and NZ 33.0 ml/min. The plasma level of Z differed little between Groups I and III, but the area under the curve was significantly higher in Group III than in Group I subjects (AUC0–144=17.3 and 6.8 µmol·l−1·h, respectively). Severe renal failure did not affect the peak plasma concentration of NZ but it did significantly increase peak time, apparent elimination half-life, and the area under the plasma concentration curve. A significant inverse relationship was found between renal clearance of NZ and plasma creatinine. Since NZ is as pharmacologically potent as Z, the results suggest that the dose of Z should be reduced in patients with severe renal insufficiency.
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  • 64
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    European journal of clinical pharmacology 28 (1985), S. 585-588 
    ISSN: 1432-1041
    Keywords: isoxicam ; pharmacokinetics ; renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The accumulation and disposition of the non-steroidal antiinflammatory drug isoxicam were investigated following its oral administration to 6 subjects with normal renal function and 13 patients with diminished renal function. Isoxicam was given daily as a single oral dose for 14–15 consecutive days. Steady-state plasma levels were achieved after 13 days. The effect of differences in renal function on the kinetics of isoxicam appeared to be minimal. Accumulation of isoxicam was similar in both groups of subjects and there was no significant difference between the groups in the plasma clearance or terminal half-life of isoxicam. There were substantial differences between individuals in the apparent plasma clearance and half-life of the drug, and this is reflected in the 7-fold range of steady-state plasma isoxicam concentrations encountered in the subjects.
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  • 65
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    European journal of clinical pharmacology 28 (1985), S. 589-595 
    ISSN: 1432-1041
    Keywords: antipyrine ; chronic renal failure ; drug metabolism ; metabolism ; cumulation ; renal excretion ; pharmacokinetics ; clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In the present study the influence of chronic renal insufficiency on antipyrine clearance, metabolite formation and excretion was investigated in 8 patients. After oral administration of antipyrine, the parent compound, its metabolites and their conjugates were assayed in plasma and urine. Besides the parent drug, 3-hydroxymethylantipyrine (HMA) was present in plasma in the free and conjugated forms, whereas 4-hydroxyantipyrine (OHA) and norantipyrine (NORA) were found only in the conjugated form. The same was true for urine. The plasma concentrations of these metabolites are too low to be measured in subjects with normal renal function. Plasma antipyrine clearance in the patients was in the same range as in healthy subjects. Investigation of metabolite kinetics, however, revealed that the rate of formation of NORA was preferentially decreased, whereas that of OHA and HMA were unaltered. Renal clearance of the metabolites of antipyrine was severely impaired in patients with renal insufficiency, and the resulting accumulation made it possible for the first-time to measure the antipyrine metabolites in plasma. Mean residence times of metabolites were longer than that of the parent compound. Renal clearances of the conjugates were correlated with the creatinine clearance, but were somewhat higher. Renal clearance of free HMA was lower and was also correlated with creatinine clearance. The mean clearance for glucuronidation of HMA was 93.1 ml/min. The results suggest that in healthy subjects Phase I metabolism is the rate-limiting step in the elimination of antipyrine, which is essential for its application as a model drug in metabolism studies.
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  • 66
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    European journal of clinical pharmacology 28 (1985), S. 611-613 
    ISSN: 1432-1041
    Keywords: molsidomine ; angina pectoris ; pharmacokinetics ; molsidomine retard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Molsidomine (N-carboxy-3-morpholino-sydnonimine-ethylester; Cassella-Riedel Pharma GmbH, Frankfurt/M. FRG) has an antianginal effect for up to 3–5 h after oral administration of 2 mg Corvaton [1]. Plasma levels of the parent drug can be measured during this interval. A new galenic formulation (Corvaton retard) has been developed to prolong the duration of the therapeutic action and to improve patient compliance. The present study was carried out to establish whether the in vitro dissolution profile of the tablet was reflected in vivo, thus permitting prediction of plasma molsidomine levels in patients with coronary heart disease.
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  • 67
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    European journal of clinical pharmacology 27 (1985), S. 713-719 
    ISSN: 1432-1041
    Keywords: flucloxacillin ; cardiac pacemaker ; pharmacokinetics ; protein binding ; tissue fluid ; elderly patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of flucloxacillin in plasma and tissue fluid after i.v. infusion of 1 g was analyzed according to an open two-compartment model in 19 patients with bradyarrhythmias (mean age 70.8 years) admitted for implantation or replacement of a permanent pacemaker system. After the first infusion of flucloxacillin (5 min), the distribution phase was rapid (t1/2α=0.13 h). The plasma half-life of elimination (t1/2β) was 1.51 h, which is almost twice as long as reported in healthy volunteers. Total plasma clearance (93.1 ml/min) was also lower than is usually found in healthy individuals, due to low renal clearance of flucloxacillin (60.2 ml/min). The total apparent volume of distribution during the β-phase (Vdarea) was 0.172 l/kg and distribution in the central compartment (Vc) 0.064 l/kg. In each patient plasma protein binding and drug distribution to plasma water, proteins and blood cells in whole blood were determined. Binding in plasma to proteins was 91.0% and distribution to blood cells in whole blood 13.8%. The mean distribution volume of free flucloxacillin during the β-phase (Vdβ free) was 2.18 l/kg, which exceeds total body water, suggesting possible intracellular distribution and substantial tissue binding. Plasma concentrations of flucloxacillin after the fourth dose (1 g t.i.d.) were very similar to those obtained after the first infusion and those predicted from the single dose kinetics. The concentration of flucloxacillin in fluid from the pacemaker pockets in 5 patients averaged 12.1 µg/ml and 9.5 µg/ml at 1 and 5 h, respectively, which was more than ten times the MIC-values for Staphylococcus aureus and S. epidermidis. The average concentration ratio (tissue fluid/plasma) was 0.57. Thus the pharmacokinetics of flucloxacillin in these elderly patients exhibited marked differences from what has been found in healthy volunteers. Despite the high degree of plasma protein binding, flucloxacillin appears to distribute rapidly and efficiently to extravascular compartments, such as a pacemaker pocket.
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  • 68
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    European journal of clinical pharmacology 29 (1985), S. 21-24 
    ISSN: 1432-1041
    Keywords: nisoldipine ; nifedipine ; pharmacokinetics ; pharmacodynamics ; calcium channel blocking drugs ; hypertension ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacodynamic and pharmacokinetic profiles of nifedipine and nisoldipine were compared in a double blind, placebo-controlled study. Nisoldipine, 10 mg significantly reduced systolic blood pressure but nifedipine 20 mg retard did not, although both drugs had significant pharmacodynamic effects as evidenced by increased heart rates. The terminal elimination half-life in plasma was similar for both drugs with a mean of 2 h. The pharmacodynamics of nisoldipine were studied in 8 hypertensives following both acute and chronic administration. Antihypertensive efficacy was demonstrated after acute dosing and was maintained over 4 weeks of twice daily treatment as monotherapy.
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  • 69
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    European journal of clinical pharmacology 29 (1985), S. 79-84 
    ISSN: 1432-1041
    Keywords: dextropropoxyphene ; norpropoxyphene ; pharmacokinetics ; single dose ; multiple dose ; prediction ; saturation ; auto-induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of dextropropoxyphene (DP) and its main metabolite norpropoxyphene (NP) were studied in 6 healthy male subjects after a single oral dose of 195 mg DP HCl, and during and after 12 daily single oral doses of 195 mg DP HCl. The kinetics varied up to five-fold between individuals after the single dose, the apparent mean elimination half-life (t1/2) was 16 h for DP and 29 h for NP. The mean apparent overall plasma clearance (CL) for DP was 2.61/min. There was no systematic difference in DP clearance between the single and multiple doses, but the accuracy of individual predictions from single to multiple doses was poor, probably because of imprecise determinations of the AUC and t1/2 in the single dose experiments. The individual correlation between single and multiple dose kinetics was good for NP, although the predicted plasma levels during steady state were significantly higher than the observed levels (mean AUCss/AUCsd: 0.81). There was no sign of saturation kinetics on repeated administration. In fact, autoinduction, resulting in significantly lower plasma concentrations after treatment for 1 week was found for NP and was indicated for DP. On discontinuing DP after 12 days of treatment, the apparent mean t1/2 of DP was 23 h and of NP 25 h.
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  • 70
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    European journal of clinical pharmacology 29 (1985), S. 85-89 
    ISSN: 1432-1041
    Keywords: triamcinolone acetonide ; triamcinolone acetonide phosphate ; pharmacokinetics ; high dose ; glucocorticoids ; renal excretion ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Triamcinolone acetonide in the form of its phosphate ester was given intravenously in two different doses (10 mg/kg and 80 mg). Plasma levels of the ester and triamcinolone acetonide were measured and pharmacokinetic parameters were calculated. The pharmacokinetics both of the phosphate and the free alcohol were dose-dependent. No unchanged ester was found in the urine, indicating complete conversion of the pro-drug. Triamcinolone was not a major metabolite of triamcinolone acetonide in humans. Renal clearance was low and independent of the dose. Only about 1% of the dose was found in the urine as triamcinolone acetonide.
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  • 71
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    European journal of clinical pharmacology 29 (1985), S. 91-95 
    ISSN: 1432-1041
    Keywords: midazolam ; 1-hydroxymethylmidazolam ; pharmacokinetics ; dose proportionality ; benzodiazepine ; healthy volunteers ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of midazolam and 1-hydroxymethylmidazolam were investigated following oral administration of 7.5, 15 and 30 mg doses of midazolam in solution to 12 healthy subjects. Compared to the 7.5 mg dose, the Cmax and AUC parameters of both midazolam and 1-hydroxymethylmidazolam increased proportionally after the 15 mg dose and more than proportionally after the 30 mg dose. The t1/2 for midazolam remained relatively constant between the 7.5 and 15 mg doses whereas it increased slightly but significantly after the 30 mg dose. These data indicated that the pharmacokinetics of midazolam and 1-hydroxymethylmidazolam were linear between the 7.5 and 15 mg oral dose range. However, after the 30 mg dose, the systemic availability of midazolam and the AUC for 1-hydroxymethylmidazolam appeared to be greater than that anticipated from the lower doses, possibly due to saturation of midazolam first-pass metabolism. This ist not expected to have any clinical significance under the conditions of therapeutic use.
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  • 72
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    European journal of clinical pharmacology 29 (1985), S. 97-103 
    ISSN: 1432-1041
    Keywords: bupropion ; metabolites ; pharmacokinetics ; single and multiple dose ; side-effects ; enzyme induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of bupropion and 3 of its basic metabolites were determined in 8 young, healthy, male volunteers after single and multiple oral doses of bupropion. Plasma profiles were obtained: 1) after a single 100 mg oral dose of bupropion hydrochloride, 2) following administration of 100 mg 8-hourly for 14 days and 3) again after a single 100 mg dose 14 days later. Plasma concentrations of the parent drug and metabolites were determined by high-performance liquid chromatography. Saliva secretion and pupil diameters were measured, subjective assessments of sleep made using visual analogue scales and side effects, blood counts and biochemistry were monitored. After the first dose mean elimination half lives (t1/2) of bupropion, and metabolites I and II were 8, 19 and 19 h respectively. On repeated administration there was little accumulation of the parent drug and no evidence for induction of its own metabolism. Accumulation of I was consistent with its rate of elimination after single doses while that of II was greater than predicted with prolongation of t1/2 to 35 h. Metabolite III was barely detectable after single doses but its accumulation on multiple dosing was consistent with its long half life (35 h) determined on occasion 2. Saliva secretion was significantly reduced during the multiple dosing period but there were no complaints of dry mouth. Subjective assessments of sleep were not significantly altered though one subject reported vivid dreams. There were no other adverse reactions.
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  • 73
    ISSN: 1432-1041
    Keywords: amiodarone ; desethylamiodarone ; iodine ; pharmacokinetics ; thyroid function ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 23 patients treated with the iodine-containing antiarrhythmic drug amiodarone, the plasma concentrations of amiodarone, desethylamiodarone and iodine have been studied. Besides amiodarone and desethylamiodarone, a pool of iodine-containing substances, NANDAI (non-amiodarone-, non-desethylamiodarone-iodine), was present. At steady state the iodine content of NANDAI amounted to 64% and the iodine content of amiodarone plus desethylamiodarone to 36% of total serum iodine. At steady state 26% of the NANDAI fraction was made up of inorganic iodide, the average plasma concentration of which was at least 40 times above the upper limit of the normal range. The serum elimination half-life of NANDAI of 57–160 days exceeded that of amiodarone (35–68 days) and of desethylamiodarone (31–110 days). At steady state the serum concentration of desethylamiodarone appears to be related to the concentration of amiodarone by a Michaelis-Menten type function, yielding a Km of amiodarone of 2.45 µmol/l and a maximal desethylamiodarone concentration of 3.61 µmol/l.
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  • 74
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    European journal of clinical pharmacology 29 (1985), S. 443-446 
    ISSN: 1432-1041
    Keywords: dysmenorrhoea ; ibuprofen ; intra-uterine pressure ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Intra-uterine pressure was recorded in a dysmenorrhoeic patient for 10 h before and after administration of a single dose of ibuprofen 400 mg. Bloodsamples were obtained at regular intervals during the recording for determination of the serum concentration of ibuprofen by reverse HPLC. The maximum serum concentration (37.4 µg Ml−1) was achieved after 1 h and the terminal half-life of ibuprofen was approximately 2 h. A marked reduction in intra-uterine pressure and the severity of pain was recorded 1.5 h following the administration of ibuprofen. Despite low or non-detectable serum concentrations of ibuprofen after 4 h, intra-uterine pressure never regained the level recorded before treatment.
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  • 75
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    Bulletin of experimental biology and medicine 100 (1985), S. 1558-1560 
    ISSN: 1573-8221
    Keywords: phosphocreatine ; pharmacokinetics ; man ; experimental animals ; intravenous infusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 76
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    Neuroradiology 27 (1985), S. 172-175 
    ISSN: 1432-1920
    Keywords: Iohexol ; contrast media ; CSF ; pharmacokinetics ; myelography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The absorption of iohexol from the subarachnoid space was studied in 9 patients. Serum concentrations of iohexol were measured for a minimum of 24 hours after injection. Peak serum concentrations were observed after 2.2 (1.7–2.7) hours. The half-life of the subsequent decrease in serum concentrations was 3.4 (2.2–7.9) hours. Concentrations of iohexol in cerebrospinal fluid were 0.29–4.3 mg I/ml 24 hours after injection (7 patients). Serum and cerebrospinal fluid concentrations of iohexol are comparable to those found after intrathecal injection of metrizamide.
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  • 77
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    European journal of nutrition 24 (1985), S. 113-119 
    ISSN: 1436-6215
    Keywords: Chloramphenicol ; pharmacokinetics ; residue ; pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Residues of Chloramphenicol (CAP) were examined in 24 pigs after intramuscular injection of 30 mg CAP/kg body weight. Two pigs were slaughtered after 3, 6, 12,18, 24, 36 hours, 2, 3, 6, 10, 21 and 30 days, respectively. CAP-concentrations were determined in muscle, blood, urine, liver, kidney, bile, and fat. Methods used were gas-liquid chromatography and radioimmunoassay. Detection limits reached were 1−5 ppb. The concentration-time curves obtained reflected a long elimination phase and allowed only calculation of this half-life. Elimination half-life was estimated to be for muscle, blood and urine 160–170 hours, for kidney 310 and for bile 250 hours. Significant correlations were found to exist between CAP-concentrations in plasma and muscle. It appears that blood would be a good body fluid for monitoring CAP-residues in tissue.
    Notes: Zusammenfassung Zur Untersuchung des Rückstandsverhaltens von Chloramphenicol (CAP) wurden 24 Mastschweine, 24–28 Wochen alt, intramuskulär mit 30 mg CAP/kg Körpergewicht behandelt und je 2 Tiere nach 3, 6, 12, 18, 24, 36 Stunden, 2, 3, 6, 10, 21 und 30 Tagen geschlachtet. Die CAP-Gehalte in Muskulatur, Blut, Urin, Leber, Niere, Galle und Fett wurden gaschromatographisch und radioimmunologisch bestimmt. Die Nachweisgrenze beider Methoden liegt in Abhängigkeit von der Matrix zwischen 1 und 5 ppb. Die erhaltenen Kinetiken weisen eine terminale Elimination auf, deren Halbwertszeiten für Muskulatur, Blut und Urin ca. 160–170 Stunden, für Niere 310 Stunden und für Galle 250 Stunden betragen. Die CAP-Konzentration in Muskulatur und Blut weisen eine signifikante, lineare Korrelation auf. Blutuntersuchungen könnten deshalb als Screening-Methode bei umfangreichen Rückstandskontrollen eingesetzt werden.
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    Investigational new drugs 3 (1985), S. 361-368 
    ISSN: 1573-0646
    Keywords: 4′-deoxydoxorubicin ; esorubicin ; anthracycline ; anticancer agent ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of esorubicin, a new anthracycline antibiotic, was investigated in conjunction with a phase I clinical trial. The drug was administered to 12 patients as an intravenous bolus at a dose of 20 to 40mg/m2. All patients had normal renal and hepatic functions and no third space fluid accumulation. Plasma and urine samples were assayed by HPLC. The peak plasma concentration of esorubicin was 0.74 ± 0.57 μM (mean ± SE). Esorubicin disappeared from plasma according to a tri-exponential pattern with a terminal half-life of 20.4 ± 7.3 hr. The area under the plasma concentration versus time curve was 0.64 ± 0.31 μMxhr. Total body plasma clearance was 45.5 ± 26.8 liter/min/m2 and the apparent volume of the central compartment, 41.0 ± 24.8 L. A single metabolite, 4′-deoxydoxorubicinol, was detected in plasma. This metabolite was observed in 5 patients only and its mean peak concentration was 0.029 ± 0.017 μM. The area under the plasma versus concentration time curve for 4′-deoxydoxorubicinol was 0.02 ± 0.014 μMxhr. The urinary excretion of total fluorescence within 5 days of therapy was 7.3 ± 1.3% of the administered dose. Esorubicin represented more than 80% of the excreted anthracyclines. As in plasma, 4′ -deoxydoxorubicinol was the only metabolite detectable in urine. No correlation between the various pharmacokinetic parameters and drug-induced toxicity was observed in this small group of patients.
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  • 79
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    Investigational new drugs 3 (1985), S. 35-41 
    ISSN: 1573-0646
    Keywords: 5,6-dihydro-5-azacytidine ; leukemia (L1210) ; infusions (in vivo) ; clonogenic assays (in vitro) ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma kinetics of 5,6-dihydro-5-azacytidine (DHAC) was determined in mice using an HPLC method following an intravenous dose of 2000 mg/kg (LD10). Pharmacokinetic parameters calculated from these single dose data were sufficient to predict steady state plasma concentrations produced by s.c. infusion of DHAC. Lethal toxicity (LD66) occurred at an infusion rate of 37 mg/kg/h (111mg/m2/h), corresponding to a plasma steady-state DHAC concentration 38 ± 14 μg/ml when the infusion time was 96 h; no lethality occurred at infusion times of 72 h or less. In vitro clonogenic assays and in vivo therapeutic experiments with L1210 tumor indicated that increasing the exposure time at concentrations near 25 μg/ml from 24 to 72 h increased the cell kill only slightly. The maximum log cell kill of L1210 estimated from either in vitro or in vivo data was 1.5 logs.
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  • 80
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    Investigational new drugs 3 (1985), S. 101-107 
    ISSN: 1573-0646
    Keywords: mitoxantrone ; pharmacokinetics ; mode of action ; elimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Although a number of investigators have established that mitoxantrone (Novantrone®; dihydroxyanthracenedione) inhibits RNA and DNA synthesis and intercalates with DNA in vitro, its exact mechanism of action is unclear. Mitoxantrone is structurally related to a series of substituted anthraquinones and has features known to be essential for DNA intercalation; however, we have determined recently that mitoxantrone binds DNA in intact L1210 leukemia cells by a non-intercalative, electrostatic interaction and induces both protein associated and non-protein associated DNA strand scissions. The difference between mitoxantrone and doxorubicin with respect to their interactions with DNA could account for their relative lack of cross-resistance in the treatment of lymphoma and acute leukemia. Distribution and half-life data provide a pharmacological rationale for the use of mitoxantrone on an intermittent dosing schedule. Considerable evidence exists to suggest that mitoxantrone undergoes extensive metabolism, probably in the liver. Preliminary data show that abnormal liver function leads to decreased rates of total body mitoxantrone clearance, suggesting a possible need for dose reduction in patients with severe liver dysfunction. The most important route of mitoxantrone elimination appears to be fecal. Because of the relatively low urinary excretion it is unlikely that the standard drug dose must be reduced in the presence of compromised renal function.
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  • 81
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    Investigational new drugs 3 (1985), S. 375-381 
    ISSN: 1573-0646
    Keywords: CGP 15720A ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Pharmacokinetics of CGP 15720A have been studied in patients receiving this drug in a short I.V. infusion during its phase I clinical trial. Plasma decay was biphasic with a mean t1/2β of 4.9 ± 2.47h. The drug was cleared rapidly from plasma (7.02 ± 5.95 L/h). Renal clearance (4.13 ± 1.65 L/h) appears to be the major clearance pathway. The steady state volumes of distribution of the drug indicate limited tissue distribution for the drug. Studies with plasma and urine of patients receiving 14[C] GCP 15720A indicate that the drug is not metabolized. CGP 15720A could be measured in cerebrospinal fluid.
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  • 82
    ISSN: 1573-0646
    Keywords: pharmacokinetics ; metabolism ; mitoxantrone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An HPLC method using paired-ion chromatography on RP C-18 material was developed. After sample clean up on XAD columns, mitoxantrone (Novantrone®; dihydroxyanthracenedione) in concentrations below 1 ng/ml in serum and 0.2 ng/ml in urine were measurable with a coefficient of variation 〈9.3% at a wavelength of 658 nm. Four metabolites were separated in urine. The major metabolite cochromatographed with the synthesized dicarboxylic acid of mitoxantrone. Within 48 hours 4.4% of the administered dose was excreted in urine as mitoxantrone, 0.5% as metabolite 1 and 0.3% as metabolite 2. The pharmacokinetic parameters are adequately described by a three-compartment model with a terminal half-life of 214.8 hours, and a volume of distribution (ss) of 3792 litres. The total body clearance was 358 ml/min and the renal clearance was 26.2 ml/min.
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  • 83
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    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 243-264 
    ISSN: 1573-8744
    Keywords: chlortetracycline (aureomycin) ; citric acid ; pharmacokinetics ; physiological ; turkeys ; fowl cholera ; disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A physiologically based pharmacokinetic model was developed to describe the absorption and disposition of chlortetracyline (CTC) in the healthy and diseased (fowl cholera) turkey. The CTC was given (with and without citric acid) as an oral (15 mg/kg) or i.v. (1 mg/kg) dose. When minerals (0.3 g/LCa2+, 0.1 g/LMg2+) were dissolved in the bird's drinking water, the model indicated that the addition of citric acid (mass ratio of 10 citrate:1 CTC) increased the fraction of dose absorbed from 0.06 to 0.16; once absorbed, the fractions of drug eliminated by renal excretion, biliary secretion, and chemical decomposition were 50, 46, and 4%, respectively. The presence of fowl cholera appeared to increase plasma levels by increasing the intestinal permeability and lowering the hepatic and/or renal clearance.
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  • 84
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    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 309-346 
    ISSN: 1573-8744
    Keywords: clearance curves ; pharmacokinetics ; tracer kinetics ; homogeneous compartments ; multiexponentials ; negative powers of time ; gamma functions ; random walks with drift ; distributions of time intervals ; Inverse Gaussian distributions ; convolutions ; models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract When a clearance curve in pharmacokinetic studies- and in tracer kinetics in general — is well fitted by a sum of negative exponentials of time, in very many cases the data would also be well fitted over much or all of the same period by a function of time consisting mainly of a negative power or by a gamma function. There are also instances where two such power functions can be observed in the same clearance curve. Examples are given from numerous reanalyses of published results. These facts have not been explained, except as being fortuitous, by any existing theory or model based on two or more homogeneous compartments. Theoretical and practical implications are outlined and some general recipes are put forward with a view to replacing multicompartmental analysis.
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  • 85
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    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 405-423 
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; methyldopa ; first-pass effect ; enterohepatic recirculation ; apparent bioavailability ; dogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract α-Methyldopa was intraarterially and orally administered to dogs at two dose levels in a randomized complete crossover design. The appearance of secondary peaks in the plasma concentration-time profiles indicated the presence of enterohepatically recycled methyldopa. This was established by the absence of a secondary peak following readministration of a dose after biliary cannulation and the detection of methyldopa in the bile of a cannulated dog. Enterohepatic recirculation was estimated to account for a mean of 16.2% of the area under the plasma concentration—time profile after intraarterial administration. Total systemic clearance, defined as the sum of elimination by all routes from the general circulation of the administered dose, and corrected for enterohepatic recirculation, averaged (±SD) 99.4 ±24.6 ml/min in the dog. An extended average apparent terminal half-life of 6.0±5.2hr was exhibited after oral administration compared to an average half-life of 3.1 ±1.8 hr following intraarterial administration. Elimination kinetics were linear in the dose range studied. Oral plasma concentration data suggest that the apparent bioavailable fraction may be dose dependent.
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    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 387-403 
    ISSN: 1573-8744
    Keywords: cerebrospinal fluid ; pharmacokinetics ; ACNU ; DFMO ; MGBG ; beagle dogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two mathematical approaches are described to approximate the distribution of compounds (e.g., drugs) in the cerebrospinal fluid (CSF) downstream of or distal to both the ventricular injection site and the cisterna magna sampling site. The first approach uses a graphic representation and is, in essence, model independent;the second approach considers the geometry and physiology of CSF distribution and clearance. In all studies, radiolabeled inulin was used as an “internal standard” since it is not metabolized and is eliminated from the CSF primarily by bulk flow. Temporal comparison of the study compound to radiolabeled inulin in the cisternal CSF allowed testing of these models in beagle dogs. One use of this data is in the estimation of the drug exposure integral for antineoplastic drugs administered in the CSF to treat leptomeningeal neoplasia.
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    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 549-554 
    ISSN: 1573-8744
    Keywords: mean residence time ; statistical moments ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The present communication seeks to end a controversy created by a recent publication regarding the applicability of statistical moment principles for determination of mean residence time of drug in the body ¯tb.It is shown that the equation ¯tb=AUMC/AUC iscorrect when applied to pharmacokinetic systems in which the total drug elimination rate is directly proportional to the drug concentration in the systemic circulation, i.e., firstorder central elimination. More general equations for ¯tb in terms of elimination rate, amount eliminated, and amount in the body are presented along with demonstrations of their utility.
    Type of Medium: Electronic Resource
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  • 88
    ISSN: 1573-8744
    Keywords: cefotaxime ; pharmacokinetics ; metabolites ; probenecid interaction ; renal tubular secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of cefotaxime were investigated in human volunteers given constant intravenous infusions, intravenous bolus, and intramuscular doses of the drug. After intravenous dosing, the plasma levels of cefotaxime declined in a biphasic manner with a terminal half-life varying between 0.92 and 1.65 hr. Moreover, the pharmacokinetics were linear up to at least a 2.0 g dose for volume of distribution based on area (23.3–31.31), plasma clearance (249–288 ml/min), and renal clearance (151–177 ml/min). Renal tubular secretion of intact cefotaxime and each of its metabolites was demonstrated by its interaction with probenecid, although the ratio of drug to metabolites ultimately excreted in urine after probenecid was similar to that seen normally (54±6, 19±4, 6.5±0.7 and 5.5±0.7% for cefotaxime, DACM, M2, and M3, respectively, when calculated as a percentage of the dose). The observed half-lives of DACM, M2, and M3 were 2.3±0.4, 2.2 ±0.1 and 2.2 hr, respectively. However, when the true half-life of DACM was calculated (0.83±0.23 hr) it was not only significantly shorter than that observed but also shorter than that for intact cefotaxime. The plasma clearance of DACM (744 ±226 ml/min) was much higher than that of cefotaxime while the volume of distribution was of a similar order (56 ±241). When administered intramuscularly, there was good absorption of cefotaxime from the site of injection (92–94%) giving maximum plasma levels of the drug of between 30 and 35 mg/l at approximately 40 min after dosing. Thereafter, the plasma levels of cefotaxime declined in a monophasic manner with a half-life (1.0–1.2 hr) similar to that of the terminal half-life seen after intravenous administration. Lidocaine had no significant effect on either its absorption or elimination kinetics.
    Type of Medium: Electronic Resource
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  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 41-53 
    ISSN: 1573-8744
    Keywords: theobromine ; pharmacokinetics ; metabolism ; urinary data ; rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of theobromine (3, 7-DMX) and its metabolites was investigated in detail in four male rabbits after bolus intravenous injection (4 mg/kg) of the compound. Apparent first-order rate constants for the metabolic processes involved in the formation of 3,7-DMX metabolites and their excretion in urine were calculated. Theobromine, 7-methylxanthine (7-MX) and 3-methylxanthine (3-MX) were measured in blood and urine, and the other metabolites were determined only in urine. An appropriate model of 14 compartments is formulated to describe the disposition of 3,7-DMX and its metabolites.
    Type of Medium: Electronic Resource
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  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 1-12 
    ISSN: 1573-8744
    Keywords: sulfisoxazole ; cirrhosis ; pharmacokinetics ; volume of distribution protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The disposition of sulfisoxazole was studied in six male patients hospitalized with biopsy-proven Laennec's alcoholic cirrhosis and six normal, healthy volunteers. Four of the patients were restudied at a time their liver disease had improved clinically. On the average, compared to the normal group, the metabolism of sulfisoxazole (clearance values with respect to unbound concentration values) appears to be unaltered for the cirrhotic patients. For patients with alcoholic cirrhosis having normal renal function for age and weight, the renal elimination of sulfisoxazole was normal For those subjects with decreased renal function, the renal clearance of sulfisoxazole appeared to be disproportionately decreased, as evidenced by a lower-than-normal sulfisoxazole renal clearance-to-creatinine clearance values. The apparent steady-state volume of distribution of unbound sulfisoxazole was not altered in cirrhotic patients when compared to normal subjects, while the apparent volume of distribution of total drug increased by more than what could be expected from protein binding changes alone. The elimination rate constant did not differ from values found in normals. These data suggest that the total binding capacity of sulfisoxazole in cirrhotic patients is not different from that of normal subjects.
    Type of Medium: Electronic Resource
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  • 91
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    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 173-184 
    ISSN: 1573-8744
    Keywords: diminazene ; pharmacokinetics ; protein binding ; plasma/rbc partition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetic behavior of diminazene in plasma after administration of 2 mg/kg i.v. and 3.5 mg/kg i.m. was studied in four healthy Dala × Ryggja rams. Following i.v. injection, the data were satisfactorily described by a triexponential equation; the apparent volume of distribution at the steady-state was 0.56±0.04 L/Kg (X±sd; n=4); total body clearance averaged 1.1±0.09 ml/kg/min and elimination half-life was 9.30±1.40 hr. After intramuscular administration peak plasma levels of 6.30–7.57 μg/ml were reached in 20 to 45 min and the mean absorption time averaged 5.83±1.61 hr. Systemic availability relative to the intravenous dose was 95.10±23.21% and mean residence time averaged 14.16±1.55hr. The partition of diminazene between erythrocytes and plasma averaged 0.64±0.10; plasma protein binding was high (65–85%) and concentration-dependent. Based on the experimental data obtained, an initial i.m. dose of 2.5 mg/kg followed by 2 mg/kg 24 hr later should be safe and effective in cases of babesiosis and trypanosomiasis sensitive to diminazene. A preslaughter withdrawal period of 14–26 days was estimated.
    Type of Medium: Electronic Resource
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  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 373-386 
    ISSN: 1573-8744
    Keywords: Metabolite ; pharmacokinetics ; fraction metabolized ; cinromide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A previous study of the metabolic fate of cinromide (3-bromo-N-ethylcinnamamide) in rhesus monkey established that half of a dose is metabolized byN-deethylation to an active metabolite, 3-bromocinnamamide. Both cinromide and its proximal metabolite can be metabolized by amide hydrolysis to a second metabolite, 3-bromocinnamic acid, resulting in a triangular metabolic problem. This investigation was undertaken to distinguish between these two nonexclusive possibilites. A preliminary study was carried out to characterize the pharmacokinetics of 3-bromocinnamic acid. In the main study, six monkeys received an intravenous dose of cinromide, 3-bromocinnamamide, and 3-bromocinnamic acid in a randomized order. The time courses of compound administered and corresponding metabolites were followed. The following fractions of dose metabolized (mean±SD) were obtained: cinromide to 3-bromocinnamide: 0.53 ±0.24; 3-bromocinnamamide to 3-bromocinnamic acid: 0.53 ±0.21; cinromide to 3-bromocinnamic acid directly: 0.48 ±0.32. Thus, it was found that 3-bromocinnamic acid is formed directly from cinromide and from 3-bromocinnamamide. Also, as primary metabolites, 3-bromocinnamic acid and 3-bromocinamamide account for all of a cinromide dose with a mean value of 1.00±0.34. The observed variability in these fractions metabolized was explained by the fact that in the solution of the triangular metabolic problem, three clearances are assumed to remain constant over three studies.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
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    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 589-608 
    ISSN: 1573-8744
    Keywords: enterohepatic recirculation ; pharmacokinetics ; hepatic extraction ; area under the curve ; model ; bile ; simulated concentration-time curves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A physiologically realistic model is used to provide insight into the design of sampling protocols for accurate determination of AUC(0– ∞) for drugs subject to enterohepatic cycling. Through simulation of plasma concentration- time curves for such drugs it is found that (1) more than one peak is predicted after oral and intravenous administration of a single dose of drug, (2) the relative magnitude of peaks is dependent on the hepatic extraction ratio for both oral and intravenous drug administration, (3) the percent of the AUC(0– ∞) in later time intervals is also a function of the hepatic extraction ratio, and (4) present methods for the design of sampling protocols may not provide accurate estimates of AUC(0– ∞) (especially for highly extracted drugs), because (a) peaks are only evident at later times after intravenous administration when plasma sampling is less frequent, (b) much of the area occurs at later times, and (c) the amount of drug in the sampling compartment after oral administration is much lower than that after intravenous administration of drug and could be incorrectly interpreted as low bioavailability if sampling is not carried out for a long period of time. The types of oral and intravenous profiles predicted for highly extracted drugs are exemplified by data for naltrexone in the monkey.
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  • 94
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    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 355-372 
    ISSN: 1573-8744
    Keywords: methadone ; rat ; pregnancy ; physiological flow model ; pharmacokinetics ; scaleup ; opiates ; GC-MS analytical method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A physiological flow model simulating the pregnant rat is constructed for methadone. The model includes brain, fetal, hepatic, intestinal, muscular, pulmonar, and renal tissues. Since methadone kinetics may provide valuable information for optimal therapy, an attempt is made to describe methadone kinetics in brain and other tissues simultaneously. The concentration-time profiles of methadone in various tissues after an i.v. bolus dose of 2 rng/kg are reasonably described by the model. The role of the different organs in the disposition of methadone is further explored by simulations. It is found that methadone is initially sequestered in lung tissues immediately after intravenous administration. Therefore, both venous and arterial blood pools are included in the model. Rapid uptake then takes place into vascular-rich organs, including kidneys, liver, and muscle, followed by redistribution into less penetrable organs, such as brain, fetal, and intestinal tissues. Data indicate that diffusional resistance governs the transfer of drug into brain, fetal, and intestinal tissues. Simulations suggest that muscular tissues play an important role in the rat and in man, becoming the major methadone reservoir. The tissue-to-blood partition coefficients derived from equilibrium conditions in this study are generally higher than those reported hitherto. The model is scaled up to a human to investigate whether it can be used to predict the concentration of methadone in different organs after a certain dose. Volume of distribution (Vdss) and biological half-life are consistent with earlier findings in man. The study is done by means of the GC-MS method with selected ion-monitoring where deuterated methadone is used as an internal standard.
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 2 (1985), S. 55-63 
    ISSN: 0739-4462
    Keywords: precocene II ; pharmacokinetics ; detoxification ; cytochrome P-450 ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cuticular penetration and pharmacokinetics of the anti-juvenile hormone precocene II were determined in a sensitive species (Oncopeltus fasciatus) and an insensitive species (Heliothis zea). Precocene was sequestered by the fat body and slowly metabolized in Oncopeltus, but rapidly metabolized and excreted in Heliothis. Studies in vitro using inhibitors for cytochrome P-450 and for cyt P-450-NADPH-reductase, confirmed the anticipated detoxification of precocene by a mixed-function oxidase via the 3,4-epoxide. Use of the inhibitors in vivo had no influence on the metabolism of precocene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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