Pharmacokinetics of felodipine extended-release tablets in healthy Taiwanese subjects: a retrospective review.

The objective of this study was to investigate the pharmacokinetics of felodipine (CAS 72509-76-3) in healthy male Taiwanese subjects. This is a retrospective review of five felodipine pharmacokinetic studies completed in Taiwan. A total of 100 evaluable healthy Taiwanese males were enrolled in these studies. The subjects received 5 mg (n = 80) or 10 mg (n = 20) of Plendil (felodipine extended-release tablets; felodipine ER) once daily for 6 days. The mean +/- SD t(max,ss,) CG(max,ss) and AUG(tau) of dose normalized to 10 mg felodipine was 3.32 +/- 1.33 h, 13.12 +/- 5.34 nmol/L and 136.33 +/- 63.18 nmol x h/L, respectively. By using Kolmogorov-Smirnov's test and probit plots, the results indicated that the frequency distribution of AUC/dose, C(min)/dose and CL/F was bimodal. Compared to data from the literature, the mean C(max,ss) and AUG(tau) of 5 mg felodipine in healthy young Taiwanese subjects were similar to or slightly lower than data from Swedish, Danish, Turkish and Canadian studies in healthy young subjects who received 10 mg felodipine. Comparable C(max) values and approximately 30% lower AUC values were observed when comparing the 5 mg Taiwanese data to data in healthy elderly German subjects who also received 5 mg felodipine. Taiwanese subjects might have lower CYP3A4 activity to metabolize felodipine, which is similar to the phenomenon observed with nifedipine.

Electrophysiologic, pharmacokinetic, and pharmacodynamic values indicating a higher risk of torsades de pointes.

Torsades de pointes (TdP) is a major safety concern with drugs that are submitted for regulatory approval. The study aimed to identify the electrophysiological, pharmacokinetic, and pharmacodynamic values indicating a higher risk of TdP. A number of QT-prolonging drugs were assigned to 2 groups. Group 1 consisted of drugs that had been withdrawn or suspended from the market because of unacceptable TdP risk or for which numerous reports of TdP had been published. Group 2 included drugs for which there had been isolated reports or no report. The results showed that drugs in group 1 induced greater inhibition of human ether-a-go-go-related gene (HERG) potassium current or the rapid component of the delayed rectifier potassium current (I(kr)), had lower half-maximal inhibitory concentration (IC50) values for inhibition of HERG/I(kr), and induced greater QTc increases in humans. The cutoff values indicating a higher risk of TdP included an increase in action potential duration greater than 10% at concentration lower than 300 nM, inhibition of HERG/I(kr) greater than 30% at therapeutic concentration, IC50 lower than 2 µM, a mean QTc increase greater than 15.5 milliseconds in monotherapy and 12.0 milliseconds with concurrent use of metabolic inhibitors, and an upper bound of its 95% confidence interval greater than 21 milliseconds in monotherapy and 19.4 milliseconds in the presence of metabolic inhibition.

Synthesis and evaluation of 3-aroylindoles as anticancer agents: metabolite approach.

BPR0L075 (2) is a potential anticancer drug candidate designed from Combretastatin A-4 (1) based on the bioisosterism principle. Metabolites of 2, proposed from in vitro human microsome studies, were synthesized, leading to the identification of metabolite-derived analogue 10 with 40-350 pM potency against various cancer cell lines. Insights gained from the major inactive metabolite of 2 led to the development of 29, with better pharmacokinetics and improved potency in the tumor xenograft model than 2.