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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 26 (1984), S. 347-355 
    ISSN: 1432-1041
    Schlagwort(e): cimetidine ; cirrhosis ; pharmacokinetics ; bioavailability ; clearance reduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of impaired liver function on the pharmacokinetics of cimetidine was studied in 8 patients with advanced cirrhosis given single doses of 100 mg i.v. and 400 mg p.o. on separate days. Compared to a control group of 10 healthy volunteers, the total renal and nonrenal clearance was significantly reduced in the cirrhotic patients; (total plasma clearance mean ± SD) 356±181 vs 789±262 ml/min (p〈0.01); renal clearance (Clr) 296±100 vs 588±181 ml/min (p〈0.01) and nonrenal clearance (Clnr) 97±111 vs 205±89 ml/min (p〈0.05). Compared to published results for age-matched ulcer patients, both total and nonrenal clearance were lower whereas renal clearance was within the reported normal range. A significant reduction in volume of distribution (Vdβ) was found, from 2.1±0.1 l/kg in controls to 1.0±0.4l/kg, and in the patient group there was a significant correlation between Vdβ and total plasma clearance (r=0.72, p〈0.05). Volume of distribution in steady state (Vdss) did not differ from published results in age-matched controls. No significant change in half-life was found. Bioavailability, estimated by AUC-measurement, showed considerable patient variability (21–143%), with a mean of 70±39%. This was lower than in the controls. In contrast, measurement of urinary excretion showed higher bioavailability in the patients (66±23 vs 51±8%). No correlation was found between any of the kinetic parameters and the clinical and laboratory data. It is suggested that patients with advanced cirrhosis should be closely observed when given cimetidine, and a reduction in dose should be concidered if side effects are to be avoided.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 29 (1986), S. 619-623 
    ISSN: 1432-1041
    Schlagwort(e): terbutaline ; pregnancy ; pharmacokinetics ; preterm labour ; side-effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Terbutaline in plasma was determined in three groups of women by gas chromatography-mass spectrometry. Eight women received a single i.v. dose of 0.25 mg terbutaline sulphate during pregnancy and 3–6 months after delivery. Mean plasma clearance was 29% higher during pregnancy than after delivery. There was a subsequent decrease in mean terminal half-life from 5.3 to 3.7 h and in mean residence time from 5.3 to 3.4 h. There was no change in volume of distribution. A second group of pregnant women in premature labour (n=8) received oral terbutaline 5 mg t.d.s. The dosing was repeated after delivery. The mean steady state plasma concentration of terbutaline was about 30% lower during pregnancy than after delivery. A third group of women in preterm labour (n=8) was treated with an i.v. infusion of terbutaline. The concentrations of terbutaline found on cessation of uterine contractions ranged between 12.8 and 31.5 ng/ml. At present there is no basis for formulation of a “therapeutic plasma level” of terbutaline for the treatment of preterm labour.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 16 (1979), S. 335-340 
    ISSN: 1432-1041
    Schlagwort(e): cimetidine ; enterohepatic circulation ; irregular absorption ; bioavailability ; pharmacokinetics ; volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The bioavailability and pharmacokinetics of cimetidine have been studied in healthy volunteers after administration of single intravenous (100 mg) and oral doses (100, 400 and 800 mg). After i.v. administration, the kinetics of cimetidine could be described by a linear, two compartment open model. Substantial variation in half-life was observed between subjects, with a mean value of 2.1 h (range 0.9–4.7). Cimetidine had a low hepatic extraction ratio and a high total plasma clearance, due to extensive urinary excretion of unchanged drug. After oral administration, the plasma concentration vs time curves in most subjects exhibited two marked peaks, an observation that seemed to be constant within individuals and was independent of dose. Bioavailability, estimated as the area under the plasma concentration vs time curves (AUC), after oral doses as compared to the intravenous dose, in most cases exceeded 100%. There was no correlation between bioavailability estimated as AUC and as urinary excretion of unchanged drug. These observations may indicate an enterohepatic circulatory mechanism, predominantly after oral administration. Both unchanged drug and its sulphoxide metabolite appear to be excreted in bile. The latter was shown in vitro to be reduced to cimetidine by fecal bacteria.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-1041
    Schlagwort(e): Doxycycline ; bioavailability ; pH dependent absorption ; pharmacokinetics ; carrageenate ; adverse events
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The effect of increased gastric pH (obtained by pre-treatment with omeprazole) on the bioavailability of doxycycline monohydrate and doxycycline carrageenate has been investigated in 24 healthy volunteers, using an open, randomised, four-treatment, four-period, crossover, 2×2 factorial design. Each subject received a single dose of 100 mg of each of the doxycycline formulations with and without pre-treatment with omeprazole (40 mg daily for 7 days). The two formulations were bioequivalent (rate and extent) during fasting without omeprazole pre-treatment, whereas after omeprazole, the monohydrate showed a highly significant decrease in bioavailability (38% for AUC and 45% for Cmax) compared to the carrageenate formulation, which was not affected by prior administration of omeprazole. Many of the subjects did not reach a therapeutic plasma level of doxycycline during the combination of omeprazole and doxycycline monohydrate, and most adverse events (mainly gastrointestinal) were reported after this combination. As large populations of patients have a high gastric pH due to frequent use of H2-blockers, proton pump inhibitors and antacids, as well as to physiological achlorhydria, the decreased absorption of doxycycline monohydrate may well have a clinical impact, for example when the patients are treated with tetracyclines for an infection.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1432-1041
    Schlagwort(e): Corticosteroids ; systemic effects ; plasma cortisol suppression ; white blood cell count ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The systemic effects of single and multiple doses of inhaled fluticasone propionate (FP) and budesonide were examined in 24 healthy male volunteers (age range 18–29 years). The study was of an open, placebo-controlled, randomized, three-way crossover design. On each study day, multiple blood samples were taken over a 20 h period after drug administration (after a single dose and after the last of seven doses) and area under the curve (AUC0–20) for plasma cortisol and white blood cell (WBC) counts was calculated. Results: The present study shows that multiple dosing with FP 1.0 mg b.i.d. for 3.5 days (seven doses) resulted in a marked cortisol suppression from placebo which, at 55%, was more than double that seen with a single dose (25% suppression). Multiple dosing with budesonide 0.8 mg b.i.d. resulted in a 34% suppression in plasma cortisol compared with a suppression of 26% with a single dose. The increase in systemic activity of FP after multiple dosing is confirmed by both the number of subjects with 0800 hours plasma cortisol values below normal limits and by the changes in WBC and differential counts. Conclusion: The results of the present study confirm previous findings with regard to the more marked systemic effect of FP following multiple dosing as compared with a single dose. This increase in systemic effect from single dosing to multiple dosing is significantly greater for FP than for budesonide.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1432-1041
    Schlagwort(e): Key words Fluticasone propionatei ; HPA-axis; bud esonide ; asthma ; children ; corticosteroids ; systemic effects ; plasma cortisol suppression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To compare the systemic potency of inhaled fluticasone propionate delivered via Diskhaler® (FP-DH), and inhaled budesonide delivered via Turbuhaler® (BUD-TBH) over the clinically recommended dose range using plasma cortisol suppression as a marker for systemic activity. Methods: The systemic potency was examined in a dose-response study in 81 healthy male volunteers. The study was of an open, randomized, parallel-group (four groups) design, where two treatments were given in crossover fashion within each group. FP-DH and BUD-TBH were given b.i.d. for 7 days (14 doses): 100 and 100 μg (group 1); 200 and 200 μg (group 2); 500 and 400 μg (group 3); 1000 and 800 μg (group 4). There was a washout period of 7 days within each treatment group. All doses were administered at 08:00 and 20:00 hours. Multiple plasma cortisol samples were taken every 2 h over 24-h periods prior to randomization (baseline) and during steady state (i.e., the last two dosing intervals). Cortisol suppression was determined by comparing average plasma concentrations of cortisol before and during treatment. Dose-response curves for cortisol suppression were analyzed using multivariate non-linear regression (Hill modeling). Results: Multiple dosing for 7 days with FP-DH and BUD-TBH resulted in dose-dependent cortisol suppression by both drugs, most pronounced at the two highest dose levels. FP-DH-induced suppression was 41% at 500 μg and 86% at 1000 μg b.i.d., while that induced by BUD-TBH was 19% at 400 μg and 47% at 800 μg b.i.d. Statistically significant differences were found when comparing the two steroids at these two dose levels. Doses producing 50% of maximum suppression (ED50) were estimated at 833 μg b.i.d. for BUD-TBH and 479 μg b.i.d. for FP-DH. This gave an estimated relative cortisol suppression over the dose range of 1.74:1 (FP-DH:BUD-TBH). ED50 values, estimated from cortisol concentrations at 08:00 hours (12 h after the last dose), were 1212 μg b.i.d. for BUD-TBH and 527 μg b.i.d. for FP-DH giving a relative cortisol suppression of 2.30:1 (FP-DH:BUD-TBH). Fourteen subjects on the highest FP-DH dose and 3 at the next highest dose had morning plasma cortisol levels below the lower reference limit. No subject taking budesonide, however, had morning plasma cortisol levels below the reference limit. Analysis of the time for return to pretreatment baseline levels showed that cortisol suppression, 12–24 h after the last dose, was statistically significant compared with the baseline for the highest dose of FP-DH but not for any of the BUD-TBH doses. Conclusions: The results of the present study show that FP-DH suppresses plasma cortisol more than BUD-TBH on a equivalent basis with regard to both magnitude and duration.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1432-1041
    Schlagwort(e): Key words Corticosteroids; systemic effects ; plasma cortisol suppression ; white blood cell count ; healthy volunteers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The systemic effects of single and multiple doses of inhaled fluticasone propionate (FP) and budesonide were examined in 24 healthy male volunteers (age range 18–29 years). The study was of an open, placebo-controlled, randomized, three-way crossover design. On each study day, multiple blood samples were taken over a 20 h period after drug administration (after a single dose and after the last of seven doses) and area under the curve (AUC0–20) for plasma cortisol and white blood cell (WBC) counts was calculated. Results: The present study shows that multiple dosing with FP 1.0 mg b.i.d. for 3.5 days (seven doses) resulted in a marked cortisol suppression from placebo which, at 55%, was more than double that seen with a single dose (25% suppression). Multiple dosing with budesonide 0.8 mg b.i.d. resulted in a 34% suppression in plasma cortisol compared with a suppression of 26% with a single dose. The increase in systemic activity of FP after multiple dosing is confirmed by both the number of subjects with 0800 hours plasma cortisol values below normal limits and by the changes in WBC and differential counts. Conclusion: The results of the present study confirm previous findings with regard to the more marked systemic effect of FP following multiple dosing as compared with a single dose. This increase in systemic effect from single dosing to multiple dosing is significantly greater for FP than for budesonide.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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