Bioequivalence evaluation of new megestrol acetate formulations in humans

The bioequivalence of two new investigational 160 mg tablets, one containing the regular form and the other a micronized form of megestrol acetate, was determined relative to a commercially available 40 mg tablet. The tablets were administered to 24 male subjects in a three-way crossover study, balanced for sequence, with 1 week between administrations. The 40 mg tablets were administered qid at 8 AM, 12 PM, 6 PM, and 10 PM, while the 160 mg tablets were administered once at 8 AM. Plasma samples were collected at appropriate times up to 96 hours after administration and were analyzed for megestrol acetate with a validated high-performance liquid chromatographic procedure. Based on the times to maximum plasma concentrations (2.5 to 2.8 h) the rate of absorption was the same for each of the tablets. Relative to the 40 mg qid dose, the 160 mg regular and the 160 mg micronized tablets had mean relative bioavailabilities of 97% and 118%, respectively.