The relative bioavailability study and fasting and fed states pharmacokinetics of bicalutamide 50-mg tablets in healthy Chinese volunteers.

The aim of this study was to evaluate the bioequivalence of a new generic formulation of bicalutamide 50-mg tablets (test) and the available branded formulation (reference) to comply with regulatory criteria for marketing of the test product in China. This single-dose, randomized-sequence, open-label, 2-period crossover study was conducted in 40 healthy male volunteers and consisted of separate fasting and fed phases. A single oral dose of the test or reference formulation was followed by a 6-week washout period, after which subjects received the alternative formulation. Blood samples were collected before dosing and at 0.5, 1, 2, 4, 8, 12, 15, 24, 30, 36, 48, 72, 144, 288, 432 and 576 h after dosing. Plasma samples were separated and assayed for bicalutamide using a selective and sensitive HPLC method with UV detection. The fasting and fed states pharmacokinetic parameters AUC0-576 h, AUC0-∞, Cmax, tmax and t1/2 were determined from plasma concentration-time profile of both formulations. The formulations were considered bioequivalent when the 90% CIs of the geometric mean ratios (test:reference) for Cmax and AUC0-576 h were within the regulatory range of 80-125%. There were no significant increases in bicalutamide Cmax, AUC0-576 h or tmax for either formulation in the fed phase compared with the fasting phase. In both the fasting and fed portions of the study, the 90% CIs for the ratio (test:reference) of log-transformed Cmax and AUC0-576 h were within the acceptance range for bioequivalence.