The aim of this analysis was to explore the influence of CYP3A4*1G and CYP3A5*3 polymorphisms on the pharmacokinetics of tylerdipine in healthy Chinese subjects. A total of 64 and 63 healthy Chinese subjects were included and identified as the genotypes of CYP3A4*1G and CYP3A5*3, respectively. Plasma samples were collected for up to 120 h post-dose to characterize the pharmacokinetic profile following single oral dose of the drug (5, 15, 20, 25 and 30 mg). Plasma levels were measured by a high-performance liquid chromatography-mass spectrometry (LC-MS/MS). The pharmacokinetic parameters were calculated using non-compartmental method. The maximum concentration (C) and the area under the curve (AUC) were all corrected by the dose given. In the wild-type group, the mean dose-corrected AUC was 1.35-fold larger than in CYP3A4*1G carriers (p = .018). Among the three CYP3A5 genotypes, there showed significantly difference (p = .008) in the t, but no significant difference was observed for the AUC and C. In subjects with the CYP3A5*3/*3 genotype, the mean t was 1.35-fold higher than in CYP3A5*1/*1 group (p = .007). And the t in CYP3A5*3 carriers also was 1.32-fold higher than in the wild-type group (p = .004). CYP3A4*1G and CYP3A5*3 polymorphisms may influence tylerdipine pharmacokinetic in healthy Chinese subjects.
Tylerdipine hydrochloride is a novel L-type and T-type dual calcium channel antagonist that has the potential effects of expanding blood vessels and lowering blood pressure. It is expected to reduce the side effect of ankle edema observed with other drugs in the same class. A randomized, open-label, crossover phase 1 study was performed to evaluate the effect of food on the bioavailability of tylerdipine. Fourteen healthy male volunteers were enrolled. The administration of tylerdipine after a high-fat meal increased the bioavailability of tylerdipine. In the fed state there was a 130% increase in the mean total systemic exposure (AUC inf ) and a 73% increase in the mean peak plasma concentration (C max ) compared with that in the fasting state. The geometric mean ratios (90% confidence interval) of C max and AUC inf were 2.54 (1.94, 3.33) and 1.75 (1.50, 2.04) for tylerdipine. The exposures of the 2 main metabolites M2 and M4 were increased by approximately 10% after a high-fat meal. The median time to peak plasma concentration of tylerdipine showed no difference between fasting and fed states.
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