The metabolism of nicardipine hydrochloride in healthy male volunteers.

Four human volunteers given a 30 mg oral dose of nicardipine hydrochloride containing 40 microCi of the 14C-labelled material achieved peak plasma levels of compound-related radioactivity within one hour of dosing. Parent compound comprised only a minor fraction of the circulating radioactivity indicating rapid first-pass metabolism. Plasma radioactivity declined to background levels within 96 h and was excreted both in the urine and faeces. Urinary excretion was the favoured route comprising about 60% of the dosed radioactivity. Mean total recovered radioactivity amounted to 94.8%. Both 1,4-dihydropyridine and pyridine metabolites of nicardipine hydrochloride were excreted in the urine. The major urinary metabolites, comprising some 36% of the radioactivity excreted in the 0-8 h post-dose period, were the glucuronide conjugates of +/- 2-hydroxyethyl methyl-1,4-dihydro-2,6-dimethyl-4(m-nitrophenyl)-3,5-pyridine dicarboxylate and its pyridine from 2-hydroxyethyl methyl-2,6-dimethyl-4-(m-nitrophenyl)-3,5-pyridine dicarboxylate.