The trough plasma concentration of felodipine in most individuals was substantially below the concentration needed to effect a half-maximal decline in blood pressure (ECĥ0), thus precluding once a day dosing with the immediate-release formulation.įollowing administration of a 10 mg dose of felodipine, the extended-release formulation, to young, healthy volunteers, mean peak and trough steady-state plasma concentrations of felodipine were 7 and 2 nmol/L, respectively. The mean peak and trough steady-state plasma concentrations achieved after 10 mg of the immediate-release formulation given once a day to normal volunteers, were 20 and 0.5 nmol/L, respectively. The mean contributions of the three individual phases to the overall AUC were 15%, 40% and 45%, respectively, in the order of increasing tįollowing oral administration of the immediate-release formulation, the plasma level of felodipine also declined polyexponentially with a mean terminal tġ/2 of 11 to 16 hours. Felodipine is greater than 99% bound to plasma proteins.įollowing intravenous administration, the plasma concentration of felodipine declined triexponentially with mean disposition half-lives of 4.8 minutes, 1.5 hours, and 9.1 hours. Both peak plasma concentration and the area under the plasma concentration time curve (AUC) increase linearly with doses up to 20 mg. Mean peak concentrations following the administration of felodipine extended-release tablets are reached in 2.5 to 5 hours.
The systemic bioavailability of felodipine is approximately 20%. With the exception of a mild diuretic effect seen in several animal species and man, the effects of felodipine are accounted for by its effects on peripheral vascular resistance.įollowing oral administration, felodipine is almost completely absorbed and undergoes extensive first-pass metabolism. The effect of felodipine on blood pressure is principally a consequence of a dose related decrease of peripheral vascular resistance in man, with a modest reflex increase in heart rate (see Cardiovascular Effects).
In vitro, but such effects have not been seen in intact animals. Negative inotropic effects can be detected In vitro studies show that the effects of felodipine on contractile processes are selective, with greater effects on vascular smooth muscle than cardiac muscle. ++ currents in vascular smooth muscle and cultured rabbit atrial cells, and blocks potassium-induced contracture of the rat portal vein. It reversibly competes with nitrendipine and/or other calcium channel blockers for dihydropyridine binding sites, blocks voltage-dependent Ca Felodipine is a member of the dihydropyridine class of calcium channel antagonists (calcium channel blockers).
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