RESUMEN
The primary objective of this study was to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of tasosartan and atenolol administered alone and concomitantly under steady-state conditions in 17 patients ages 18 to 65 years diagnosed with stage 1 to 2 essential hypertension. After a 3- to 14-day qualification period, all patients received placebo tasosartan on days--1 through 5 and 25 through 34, atenolol alone (50 mg) on days 1 through 5, atenolol (50 mg) + tasosartan (50 mg) on days 6 through 19, and tasosartan (50 mg) alone on days 20 through 24. A PK and PD evaluation of atenolol alone was performed on study day 5. On study day 19, PK and PD of both tasosartan and atenolol were assessed. PK and PD evaluation for tasosartan alone was assessed on study day 24. The coadministration of atenolol + tasosartan did not affect the pharmacokinetics of tasosartan, its major metabolite (enoltasosartan), or atenolol when compared with tasosartan or atenolol administered separately. For area under the change in diastolic blood pressure curve, the reduction was significantly greater after tasosartan + atenolol compared with that after atenolol alone (336 +/- 85 and 190 +/- 71 mmHg.24 h; p < 0.05 for combination and atenolol alone, respectively; mean +/- SEM). Combination therapy also caused a maximal reduction in diastolic blood pressure that is significantly more than with monotherapy with atenolol (-27 +/- 2 mmHg and -20 +/- 2 mmHg, respectively, p < 0.05). The additive effects of tasosartan and atenolol in decreasing diastolic blood pressure may provide a rationale for combination antihypertensive therapy.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacología , Angiotensina II/metabolismo , Antagonistas de Receptores de Angiotensina , Atenolol/farmacología , Hipertensión/metabolismo , Pirimidinas/farmacología , Tetrazoles/farmacología , Adolescente , Antagonistas Adrenérgicos beta/administración & dosificación , Antagonistas Adrenérgicos beta/farmacocinética , Adulto , Anciano , Atenolol/administración & dosificación , Atenolol/farmacocinética , Sinergismo Farmacológico , Humanos , Hipertensión/tratamiento farmacológico , Persona de Mediana Edad , Pirimidinas/administración & dosificación , Pirimidinas/farmacocinética , Método Simple Ciego , Tetrazoles/administración & dosificación , Tetrazoles/farmacocinéticaRESUMEN
The pharmacokinetics and relative oral bioavailability of procaterol, an orally active beta 2-adrenergic agonist bronchodilator were evaluated in healthy volunteers. Procaterol was rapidly absorbed after oral administration. Mean plasma procaterol concentration-time profiles and pharmacokinetic parameters for both formulations were essentially superimposable. Following tablet administration, the mean Cmax was 358 pg/mL and the corresponding mean tmax was 1.6 hr. Mean renal clearance was 163 mL/min and accounted for approximately one-sixth of the mean apparent oral plasma clearance (988 mL/min). The mean apparent elimination half-life of procaterol was 4.2 hr. Hepatic metabolism appears to be the primary mechanism for elimination of procaterol from the body, and first-pass metabolism may limit systemic bioavailability.
Asunto(s)
Procaterol/farmacocinética , Absorción , Administración Oral , Adulto , Análisis de Varianza , Disponibilidad Biológica , Femenino , Semivida , Humanos , Masculino , Persona de Mediana Edad , Procaterol/administración & dosificación , Procaterol/sangre , Procaterol/orina , RadioinmunoensayoRESUMEN
As part of a multiple dose bioavailability study, 80-mg verapamil hydrochloride tablets were administered to healthy subjects every 8 hours for 15 doses. Statistically significant successive decreases in verapamil maximum plasma concentrations (Cmax) and area under the concentration-time curve (AUC) values were observed corresponding to dosing at 8 AM, 4 PM, and 12 AM. Mean Cmax and AUC values from the 12 AM dose were decreased 36% and 30%, respectively, relative to those from the 8 AM dose. Similar effects on norverapamil pharmacokinetics were observed. Decreased Cmax and AUC values show that verapamil absorption is influenced by the time of day when doses are administered. Pharmacokinetic simulation results suggest that the rate of absorption is reduced approximately by one half and two thirds during the 4 PM and 12 AM dosing intervals, respectively, relative to the 8 AM dosing interval. The reductions in verapamil absorption as a function of time of administration observed in this study may in part explain previous reports of reduced antihypertensive effect during evening and night hours as compared to daytime hours.
Asunto(s)
Verapamilo/farmacocinética , Administración Oral , Adolescente , Adulto , Disponibilidad Biológica , Humanos , Absorción Intestinal , Masculino , Factores de Tiempo , Verapamilo/administración & dosificación , Verapamilo/análogos & derivados , Verapamilo/sangreRESUMEN
The effect of temperature on drug release from meteneprost potassium vaginal suppositories was investigated using a dissolution test based on the USP I apparatus. Comparison of the dissolution results with the DSC melting behaviour revealed that drug release was extremely slow until melting of the suppository was essentially complete. The melting behaviour of the meteneprost potassium suppositories was also varied by preparing suppositories from bases with higher and broader melting ranges. The observed dissolution behaviour (at 37 degrees C) confirmed that drug release increased as the melting temperature of a particular suppository decreased. Differential scanning calorimetry, viscosity and dilatometry methods were used to characterize the suppository melting process. The effects of suppository melting range, melt temperature and composition were investigated with respect to in vitro drug release. Methodology for the HPLC determination of meteneprost in suppositories and in dissolution media are also reported.