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  • 1
    ISSN: 1432-1041
    Keywords: doxazosin ; hypertension ; alpha1-adrenoceptor inhibitor ; elderly patients ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The α1-adrenoceptor antagonist doxazosin has been compared with placebo in 40 elderly hypertensive patients (mean age 71.4 years). At the end of 10 weeks once daily treatment with doxazosin the mean 24-h post-dose changes in standing and supine blood pressure compared with placebo were −6.9/−5.6 mmHg (systolic/diastolic) and −6.2/−5.5 mmHg respectively. The reductions in standing and supine diastolic blood pressures were statistically significant compared with placebo. At the end of treatment steady-state pharmacokinetics were evaluated in 18 patients. The plasma elimination half-life during the dose interval in these patients was 16.1 h (range 10.1–27.1 h) and the median time to peak plasma concentration was 3 h (range 1–4 h). One patient was withdrawn because of adverse effects (headache, weakness, and sweating) during doxazosin treatment. Once daily doxazosin reduced diastolic blood pressure and was well tolerated in these elderly hypertensive patients.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 48 (1995), S. 373-379 
    ISSN: 1432-1041
    Keywords: Captopril ; sublingual ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of pH on the buccal and sublingual absorption of captopril was evaluated using in vitro techniques and human studies. Partitioning of captopril into n-octanol was lowest over the pH range 5 to 8 and highest at pH values 3, 4 and 9. Using the buccal absorption technique, the partitioning of captopril (2 mg) was examined in six healthy male volunteers from buffered solutions (pH 3, 4, 5, 6, 7, 8, and 9). Lowest buccal partitioning occurred at pH 3 while maximal buccal partitioning occurred at pH 7. These data clearly indicated that the buccal absorption of captopril did not obey the classical pH/partition hypothesis suggesting that mechanisms other than passive diffusion were involved in its absorption. Captopril pharmacokinetic and pharmacodynamic parameters were determined after administration of buffered sublingual captopril (pH 7, optimal pH for absorption as determined from the buccal partitioning data) and unbuffered sublingual captopril. The study was performed in eight healthy volunteers in a randomised single-blind cross-over fashion. The tmax for captopril was found to be approximately 11 minutes earlier after buffered versus unbuffered sublingual administration and AUC0–30 min increased by approximately 30% in the case of buffered captopril. Cpmax, AUC0–180 min and relative bioavailability did not differ between the buffered and unbuffered administration. Pharmacodynamic parameters (BP, heart rate and plasma renin activity) did not differ significantly between buffered and unbuffered sublingual administration. The increased rate of captopril absorption after buffered sublingual administration was small and is likely to offer little therapeutic advantage over conventional sublingual formulation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Keywords: alfuzosin ; prazosin ; alpha1-adrenoceptor antagonist ; noradrenaline ; pharmacokinetics ; pharmacodynamics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In an open dose ranging study with random inclusion of placebo, alfuzosin (α1-adrenoceptor antagonist) 1, 2.5 and 5 mg was administered to 6 healthy volunteers, 3 of the volunteers received 10 mg alfuzosin. Supine systolic blood (SBP) pressure was not reduced by alfuzosin although significant increases occurred in supine heart rate (HR) after 2.5 and 5 mg. In the standing position, SBP was reduced at 2 and 4 h with 5 mg alfuzosin; significant increases in HR occurred following 1, 2.5 and 5 mg at 2, 4, 6 and 8 h after administration. Exercise SBP was not reduced; diastolic blood pressure was significantly reduced at 4 and 6 h with 5 mg alfuzosin. More marked effects were seen in the 3 subjects who received 10 mg alfuzosin. After 1 and 5 mg, tmax ranged from 1–2 h; Cmax (4.1 to 20.8 ng · ml−1; AUC (0–24) 20 to 132 ng · ml−1 · h (1 and 5 mg respectively) increased progressively with dose indicating dose dependent kinetics; no significant changes occurred in the visual analogue scale for sedation. A comparison of alfuzosin 5 mg, prazosin 1 mg and placebo each administered for 4 days, indicated that alfuzosin did not significantly reduce standing SBP on either Day 1 or Day 4; prazosin reduced SBP at 2 and 4 h on Day 1 and 6 h on Day 4 compared to placebo. Standing HR was increased by alfuzosin at 2 h on Day 1 and Day 4; increases occurred with prazosin at 2, 4, 6 and 8 h on Day 1 and 6 h on Day 4. Supine plasma noradrenaline increased with alfuzosin and prazosin at 2 and 4 h on Days 1 and 4; the increases were not significantly different. The plasma elimination half-life (t1/2) for alfuzosin was 3.4 h and 3.1 h after acute and chronic administration; (t1/2) for prazosin was 2.6 and 2.9 h. In conclusion alfuzosin causes small reductions in systolic blood pressure, accompanied by a dose dependent increase in heart rate in the supine and standing position and following exercise.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 40 (1991), S. 393-398 
    ISSN: 1432-1041
    Keywords: Captopril ; sublingual ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In this study we compared the pharmacokinetics and pharmacodynamics of captopril after sublingual and peroral administration. Single 25 mg doses of captopril were administered sublingually and perorally on two different occasions in a randomised cross-over fashion to eight healthy volunteers aged 22–35 years. The kinetics of unchanged captopril, plasma renin activity (PRA), BP and heart rate were studied over three hours after both peroral and sublingual administration of captopril. Mean pharmacokinetic parameters for unchanged captopril after sublingual administration were: Cmax, 234 ng·ml−1; tmax, 45 min; AUC (0–3 h), 15.1 μg·ml−1. min. Mean pharmacokinetic parameters for unchanged captopril after peroral administration were: Cmax, 228 ng·ml−1; tmax, 75 min; AUC (0–3 h), 17.0 μg·ml−1. min. tmax was significantly shorter when captopril was administered sublingually; all other pharmacokinetic parameters were equivalent. The plasma captopril concentrations achieved post drug administration led to increases in PRA and reductions in BP. tmax for PRA was 86 min for sublingual captopril and 113 min for perorally administered drug. Peak PRA values were, however, not significantly different. BP, as expected, was not reduced dramatically in these healthy volunteer subjects, however, in systolic BP vs time profiles, BP was significantly lower after volunteers received sublingual captopril. Heart rate increased slightly after captopril administration; there were no differences between the two routes of administration. Administration of captopril sublingually, therefore led to a more rapid attainment of plasma captopril concentrations and had a more rapid onset of pharmacological effect when compared with peroral administration.
    Type of Medium: Electronic Resource
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