Bioequivalence study of enalapril tablets in healthy Thai male volunteers.

MANUPAT LOHITNAVY, M.S.*, SANGLAR POLNOK, M.N.S.*** The bioequivalence study of 5-mg enalapril tablets, Enaril (Biolab, Thailand) compared to Renitec (Merck Sharp & Dohme, USA) was conducted in 14 healthy Thai male volunteers follow- ing a single dose, two-period, crossover design. Each subject received 4 tablets of 5-mg enalapril tablets of both formulations with a !-week washout period. Plasma samples collected over a 24-hour period after administration were analyzed by LC/MS/MS. Pharmacokinetic parameters were deter- mined by using non-compartmental analysis. Regarding bioequivalence testing, the 90 per cent con- fidence intervals of em .. and AUC0--ratios (Enaril/Renitec) of enalapril were 86.3 -126.1 per cent and 93.0 -118.5 per cent and those of enalaprilat were 86.4 -124.1 per cent and 90.3 -116.8 per cent. Based on the European bioequivalence guideline, the 90 per cent confidence interval of Cma* and AUC 0 __ ratios of both parent and metabolite forms were within acceptable ranges of 70 -143 per cent and 80 -125 per cent, respectively. It was concluded that Enaril 5 mg tablet was bio- equivalent to Renitec 5 mg tablet. Key word : Bioequivalence, Enalapril, Enalaprilat