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  • 1
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: Key words Repaglinide ; Insulin secretagogue ; Type-2 diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The present study was designed to assess the disposition of 14C-repaglinide in whole blood, plasma, urine and faeces, and to measure the total recovery of drug-related material in urine and faeces after a single 2-mg oral dose of 14C-repaglinide during multiple dosing. Methods: In this single-centre, open-label, phase-I trial, six healthy male volunteers received 2 mg of the prandial glucose regulator, repaglinide, four times daily for 13 days, 15 min before meals. On the morning of day 7, breakfast was omitted and the dose was given as an oral solution containing 2 mg of 14C-repaglinide. Results: After oral dosing, a mean peak plasma concentration of repaglinide of 27.74 ng · ml−1 (range: 16.84–36.65 ng · ml−1) was observed with a time to peak concentration of 0.5 h. Approximately 20% of repaglinide and its associated metabolites were distributed into red blood cells. No measurable 14C-radioactivity was present in whole blood samples 6 h after dosing. Within 96 h of dosing with 14C-repaglinide, 90% of the administered dose appeared in the faeces and 8% was excreted in urine. In the plasma, the major compound was repaglinide (61%). In the urine, the major metabolites were unidentified polar compounds, the aromatic amine (M1) (24%), and the dicarboxylic acid (M2) (22%). In the faeces, the major metabolite was M2 (66% of administered dose). Therefore, repaglinide was excreted predominantly as metabolites and the major in vivo metabolite of repaglinide in humans was M2. During regular dosing for 6 days, the morning plasma trough levels of repaglinide were, with very few exceptions, almost always too low to measure, indicating the absence of accumulation at this dose of 2 mg four times daily. Repaglinide was well tolerated, and there were no episodes of hypoglycaemia. Conclusion: After oral dosing with repaglinide, the mean peak plasma concentration was rapidly attained and, thereafter, plasma concentrations decreased promptly. The major route of excretion was via the faeces. These properties make repaglinide a suitable insulin secretagogue for all patients with type-2 diabetes who retain sufficient β-cell function.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Keywords: oxprenolol ; beta-blockade ; concentration-effect relationship ; non-invasive monitoring ; exercise test ; blood pressure monitoring ; healthy volunteers ; predictive model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The relationship between the plasma concentration of oxprenolol and its haemodynamic effects during physical exercise was studied in 6 healthy volunteers, in whom BP and heart rate (HR) were continuously monitored by non-invasive techniques (Fin-A-Press-Tonometer) during repeated three-minute exercise periods for 8 h after treatment. Using the fitted pharmacokinetic curve, the drug effect was related to its plasma concentration using the Emax model. The mean EC50 for the relationship between drug concentration and heart rate during exercise (HRex) was 73.1 ng/ml, and for systolic blood pressure during exercise (SBPex) it was 112.7 ng/ml. Emax was 29.0% for HRex, and 33.2% for SBPex. There were no consistent differences between the parameters for the effects on HRex and SPBex. Thus, using a new, non-invasive technique for continuous measurement of blood pressure, the effect of a beta-adrenoceptor blocking drug on SBPex was described with similar accuracy as its effect on HRex.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1041
    Keywords: metoprolol ; plasma concentration profile ; controlled-release formulation ; slow-release formulation ; exercise heart rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma concentration-time profile and haemodynamic effects of metoprolol after the administration of metoprolol CR1 (a new multiple-unit controlled-release formulation) and metoprolol SR2 (a traditional slow-release formulation) once daily, were investigated in 12 healthy men. Data were collected over one 24-h dose interval at steady state after five days of treament. The study was a randomized, three-way, crossover comparison of metoprolol CR, 100 mg, metoprolol SR, 100 mg, and placebo. The reduction in exercise heart rate in relation to placebo treatment was used as a measure of β1-blockade. The metoprolol plasma concentration-time profile during treatment with metoprolol CR was smooth and uniform, showing a more controlled release profile than that obtained with metoprolol SR. This was demonstrated by the significantly longer time period during which the plasma concentration exceeded 75% of the maximum concentration (T75), for metoprolol CR compared with metoprolol SR (p〈0.05). The percentage peak-trough fluctuation in plasma metoprolol concentration was significantly smaller for metoprolol CR than for metoprolol SR (p〈0.001). These pharmacokinetic differences between metoprolol CR and metoprolol SR produced a different duration of clinically relevant β1-blockade, defined as a reduction in exercise heart rate of 〉10%. By this definition metoprolol CR was still effective in seven subjects and metoprolol SR in two subjects 24 h after dosing. The percentage peak-trough fluctuation in exercise heart rate over the dose interval was significantly smaller for metoprolol CR than for metoprolol SR (p〈0.001), thus demonstrating a more even β1-blockade with metoprolol CR.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 44 (1993), S. 237-241 
    ISSN: 1432-1041
    Keywords: Ambroxol ; Uricosuric effect ; uric acid clearance ; creatinine clearance ; hypoxanthine ; diurnal rhythm ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ambroxol is known to promote bronchial secretion and is used as an expectorant. Previous studies had suggested that high doses of ambroxol could reduce the plasma uric acid concentration. The present study was undertaken to confirm this finding, to determine its dose-response relationship and to identify the underlying mechanism of action. Using a placebo-controlled, double-blind parallel group design, 48 healthy male volunteers were randomly allocated to receive placebo b.d. and ambroxol 125 mg b.d., 250 mg b.d. or 500 mg b.d. (12 subjects per group). The subjects were hospitalised during a dietary run-in period of 3 days (Days -3 to -1) and a treatment period of 5 days (Days 1 to 5). On Day -1 (baseline) and Days 1 to 5, all urine was collected and blood samples were taken for the analysis of uric acid, creatinine, xanthine and ambroxol. The measurements were repeated four days after treatment had closed. Steady state plasma concentrations of ambroxol (trough levels) were reached after 2 or 3 days and were linearly related to dose. Ambroxol induced a significant, dose-dependent, reduction in plasma uric acid (250 mg b.d. about 20%; and at 500 mg b.d. about 30%). The diurnally fluctuating uric acid clearance was dose dependently increased and there was no notable effect on creatinine clearance. Plasma hypoxanthine levels were not affected by ambroxol. No severe adverse events were reported and no drug induced changes in the clinical laboratory values were observed. It is concluded that ambroxol has an uricosuric action following oral administration of higher doses (250 mg-500 mg b.d.) and it is well tolerated.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 47 (1994), S. 361-366 
    ISSN: 1432-1041
    Keywords: Ketoprofen ; diet ; bioavailability ; pharmacokinetics ; sustained release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The indirect effect of diet on the single-and multiple-dose pharmacokinetics of sustained-release ketoprofen was studied in 16 healthy male volunteers. In an open, cross-over design, 200 mg ketoprofen was administered as a gastric-juice-resistant, sustained-release tablet once daily during two periods of 5 days. A low-calorie/low-fat diet (LCFD) was given in the first period and a high-calorie/high-fat diet (HCFD) in the second period. The first meal on each day was given 4 h after drug intake. Ketoprofen plasma concentrations were measured over 24 h after the first dose on day 1 and over 36 h after the final dose on day 5 of each period. On average, plasma concentrations of ketoprofen were higher with the LCFD than with the HCFD. With the HCFD there was a tendency to longer absorption-lag times on day 5. The maximum concentration and the area under the curve over one 24-h dosage period (AUC0–24) were significantly higher with the LCFD, both on day 1 and on day 5. For AUC0–24 the differences were on average 15% (day 1) and 24% (day 5). The same tendency was observed for the amount excreted in urine over 24 h (Ae), but the difference was only significant on day 1 (14%). The elimination rate constant (Kβ) and the mean residence time were similar for the two diets, both on day 1 and on day 5. From these results, we conclude that there was an acute indirect effect of diet when a meal was had 4 h after intake of the medication. This resulted in a greater extent of ketoprofen absorption with the LCFD than with the HCFD. The absorption rate was apparently not influenced by this acute effect. The longer gastric residence time of ketoprofen with the HCFD may be the result of a long-term indirect effect on gastric emptying rate. If the extreme difference between the diets in this study is taken into account, it seems unlikely that the observed indirect effects have implications for clinical practice.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1041
    Keywords: Key words CYP2D6 ; CYP2C19 ; Dutch population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: We examined a large database containing results on CYP2D6 and CYP2C19 activity of 4301 Dutch volunteers phenotyped in the context of various clinical pharmacology studies. Methods: The subjects were given 22 mg dextromethorphan, 100 mg mephenytoin and 200 mg caffeine. For CYP2D6, the dextromethorphan/dextrorphan metabolic ratios in urine samples taken for a subsequent 8 h were used. Dextromethorphan and dextrorphan were quantified by reversed-phase high performance liquid chromatography. For CYP2C19 similarly obtained (R)-mephenytoin and (S)-mephenytoin ratios were used. (S)-mephenytoin and (R)-mephenytoin were analysed and quantified by enantioselective capillary gas chromatography. In addition, CYP2C19 poor metabolizer (PM) subjects were reanalysed after acidic pre-treatment of urine samples to confirm the PM status. Results: The investigated population mainly comprised Caucasian (98.9%) males (68%). The age ranged from 18 to 82 years. For CYP2D6, it was found that 8.0% of the subjects were PMs. The average metabolic ratio was 0.014 (0.033) for subjects who showed extensive metabolizing activity (EM) and 5.4 (7.6) for PM subjects. For CYP2C19, it was found that 1.8% of the subjects were PMs. The metabolic ratio was 0.162 (0.124) for EM subjects and 1.076 (0.040) for PM subjects. Within the EM group the metabolic ratio in females was significantly lower for CYP2D6 (−20%) and significantly higher for CYP2C19 (+40%) compared with males. For PMs there was no such difference for CYP2D6 (P = 0.79) or CYP2C19 (P = 0.20). Oral contraceptive (OC) use significantly decreased the CYP2C19 activity by 68% for mephenytoin as compared to non-OC using females. Conclusions: For CYP2D6, the PM incidence (8.0%) is in accordance with literature data. The CYP2C19, PM incidence (1.8%) is low compared to reports from other European countries. For mephenytoin, the acidification procedure has been shown to be very important for the confirmation of CYP2C19 PMs. In EM females compared to EM males, CYP2D6 activity is increased and CYP2C19 activity is reduced. For CYP2C19 in particular this reduction is substantial and most pronounced in the age range from 18 to 40 years. For CYP2C19, the reduced activity is associated with the use of oral contraceptives.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1041
    Keywords: Oxprenolol ; β-adrenoceptor blockade ; circadian rhythm ; haemodynamics ; pharmacokinetics ; exercise ; healthy volunteers ; kinetic-dynamic model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied the effect of dosage time of oxprenolol (Trasicor®) on its pharmacokinetics and pharmacodynamics in six healthy volunteers. The drug effects measured were heart rate and systolic blood pressure during exercise. Oxprenolol was taken orally at 08.00 h, 14.00 h, 20.00 h, and 02.00 h in randomized order, with 1 week between successive doses. There were differences in the pharmacokinetics of oxprenolol for the ratio between the apparent volume of distribution and systemic availability (P=0.04) and for elimination half-life (P=0.006). Both were lowest after administration at 14.00 h (163 (77) l and 1.2 (0.6) h; mean (SD)) and highest after administration at 02.00 h (229 (100) l, and 1.7 (0.6) h). The systolic blood pressure during exercise before oxprenolol did not vary with dosage time, but heart rate during exercise before intake was lowest before dosage time 08.00 h and highest before dosage time 20.00 h (P=0.03). The time-course of heart rate during exercise after oxprenolol was described by a model that incorporated the factors drug concentration and spontaneous diurnal variation. EC50 and Emax did not vary between dosage times. The spontaneous diurnal variation in heart rate during exercise was unaffected by oxprenolol, leading to an apparently greater effect of oxprenolol during the night than during the day.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 30 (1986), S. 399-406 
    ISSN: 1432-1041
    Keywords: oxprenolol ; atenolol ; beta-blockers ; blood pressure ; exercise tolerance ; perceived exertion ; heart rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of oxprenolol, a non-selective beta-blocker with moderate intrinsic sympathomimetic activity (ISA), given by the Oros delivery system, on resting and exercise heart rate and blood pressure have been compared over a 24-h period with those of atenolol, a beta1-selective blocker without ISA. The effects on maximal and submaximal exercise tolerance and perceived exertion were studied in relation to the level of beta-blockade. 9 healthy subjects were treated with placebo, atenolol, 100 mg/day and oxprenolol Oros, 16/260 mg/day in random order, each for 5 days. Progressive maximal exercise tests and submaximal endurance tests at 80% of maximum aerobic exercise capacity were performed 2, 5 and 24 h after intake of the drugs. The reduction of blood pressure 2 and 5 h after drug intake was less pronounced after oxprenolol Oros than after atenolol, but by 24 h after the last dose the effects were similar. The peak level of beta-blockade (i.e. reduction in maximal exercise heart rate) was similar after oxprenolol Oros and atenolol. The minimal level of beta-blockade 24 h after the last dose was greater after oxprenolol Oros than after atenolol. Maximal exercise capacity and submaximal exercise tolerance were impaired after both beta-blockers. The subjective feeling of exertion did not differ between placebo, atenolol and oxprenolol Oros when related to the relative work load, except after the first minute of exercise, when the rating of perceived exertion was higher after atenolol.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1041
    Keywords: Alpidem ; Anxiolytics ; pharmacokinetics ; tolerance ; metabolites ; sedation ; adverse events
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a double-blind, placebo-controlled, crossover experiment in 21 healthy male volunteers, aged 19 to 27 y, the pharmacokinetics and tolerance of the new anxiolytic drug alpidem (SL80.0342) and its three major metabolites were studied after single doses of 25, 50, 100 and 200 mg. Plasma concentrations of alpidem (in 20 subjects) and metabolites (in 6 subjects) were measured by HPLC over a period of 54 h after dosing. Cmax, tmax and AUC(0–54) and, when possible, t1/2 were determined for alpidem and metabolites and the dose linearity of the parameters was investigated. The time to peak of alpidem was dose independent in most subjects and was short (1–4 h); the mean values at the four dosing levels were 1.9, 1.7, 1.6 and 1.8 h. The peak concentration increased with the dose, the mean values being 17, 34, 88 and 115 ng · ml−1, respectively. In 50% of the subjects cmax tended to stabilize between the 100 and 200 mg dose. Dose linearity was also present for the AUC, which plateaued between the 100 and 200 mg dose in only 3 out of 20 subjects; the mean AUC was 119, 281, 669 and 1117 ng · ml−1 · h, respectively. The apparent half-life of elimination appeared to be dose independent, mean values at the increasing dosing levels being 18.7, 19.9, 18,1 and 17.9 h. A similar relationship between the kinetics parameters and dose of the alpidem was observed for the metabolites SL83.0912, SL80.0522 and SL83.0725. The formation of metabolites was not saturated as their AUCs relative to corresponding alpidem AUCs were not dose related. Thus the kinetics of alpidem and its three major metabolites were linear after doses of 25 to 200 mg. The drug was well tolerated by most of the subjects. Sedation and dizziness occurred mainly after the 100 and 200 mg doses.
    Type of Medium: Electronic Resource
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