The metabolism and pharmacokinetics of nicardipine hydrochloride in man.

Studies have been carried out to investigate the disposition of nicardipine hydrochloride following intravenous and oral administration to male volunteers. Following oral administration of a radiolabelled dose, nicardipine was shown to be rapidly and extensively metabolised and to be rapidly eliminated from plasma. After intravenous infusion of nicardipine at 5 mg-1 for 3 h, plasma levels declined biexponentially, and clearance values were of the same order as hepatic blood flow. With repeated oral administration, 20 mg three times daily for 28 days, plasma levels rose over the first 3 days of administration and then declined to some extent. Possible reasons for this decline are discussed. Steady-state plasma levels and bioavailability show a nonlinear relationship with doses over the range 10-40 mg three times daily. Food consumption has been shown to reduce the bioavailability of nicardipine when the food is taken before or at the same time as nicardipine administration.