Effects of food on the bioavailability of sustained-release pinacidil in humans

Pharmacokinetic-pharmacodynamic modeling between pinacidil or pinacidil-N-oxide plasma levels and systemic and regional hemodynamic effects in healthy volunteers

Pinacidil (P) lowers blood pressure through peripheral vasodilation, but also induces dose-dependent side-effects. In a previous placebo-controlled, randomized, double-blind and crossover study, performed in six healthy male volunteers, we investigated the systemic and regional hemodynamic effects of a single oral administration of 25 mg of P (sustained-release form) and measured the plasma concentrations of P and of its active metabolite, pinacidil-N-oxide (PO). In the present study, our goal has been to investigate the relationships between P and/or PO plasma concentrations and P administration effects on systolic, diastolic and mean arterial pressures (SAP, DAP, MAP), heart rate (HR), cardiac output (CO), total peripheral resistance (TPR), brachial and carotid arteries' diameters (BAD, CAD), flows (BAF, CAF) and vascular resistances (BVR, CVR) which were assessed before and at different time intervals after drug intake. Concentration-effect relationships were investigated using both linear and log-linear multiple regression models with P, PO or both P and PO as independent variables (six models). Significant linear relationships were observed between P and/or PO and SAP, DAP, MAP, TPR, BAD, BAF, BVR, CAD and CVR. For example, TPR (dynes.s/cm5) = 1308-3.031 x P (ng/ml), R = 0.57, P = 0.0037; BVR (mmHg.s/ml) = 58-0.261 x P (ng/ml), R = 0.56, P = 0.0042. Almost similar R values were obtained using P, PO, or both P and PO. The use of log-linear models did not improve the fittings.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of food on nifedipine sustained-release preparation

The effect of food on the bioavailability of a nifedipine sustained-release preparation was studied. Each of seven male volunteers received a single oral 20 mg dose with 100 mL of water under two conditions, fasting and after a meal, with a crossover after a seven-day wash-out period. Blood samples were drawn at time zero (just prior to dose), and 1, 2, 3, 4, 6, 8, 10, and 12 hours after dosing. Nifedipine assays were performed by gas chromatography. The area under the serum concentration-time curve (AUC) from 0 to 12 hours and maximum serum concentration (Cmax) were significantly increased by food. Blood pressure was significantly decreased by food. The mean AUC for fasting and meal conditions were 315.0 and 411.4 ng.h/mL, and the mean Cmax were 42.6 and 86.6 micrograms/mL, respectively. The results indicate that food may increase the bioavailability of nifedipine sustained-release preparation.