Bioequivalence study of two different coated tablet formulations of finasteride in healthy volunteers

This study was conducted in order to assess the bioequivalence of two different coated tablet formulations containing 5 mg finasteride (CAS 98319-26-7). Twenty-six healthy volunteers were enrolled in an open, randomised, crossover single dose study with 2 periods x 2 sequences and a minimum washout period of 7 days. Plasma samples were obtained over 24 h (at baseline, +0.5 h, +1 h, +1.5 h, +2 h, +2.5 h, +3 h, 3.5 h, +4 h, +4.5 h, +5 h, +6 h, +8 h, +10 h, +12 h, +16 h and +24 h after administration). Finasteride levels were determined by high-pressure liquid chromatography with tandem mass detection, HPLC-MS/ MS, (LOQ 0.50 ng/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUClast and Cmax were main evaluation criteria, however, AUCinf was also analysed) were determined from the finasteride concentration data using non-compartmental analysis. The 90 % confidence intervals (obtained by ANOVA) were 86.31-98.69 for Cmax, 95.40-104.88 for AUClast and 96.20-105.81 for AUCinf that is, they were all within the predefined ranges. It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.