Bioequivalence of two oral formulations of glyburide (glibenclamide).

Glyburide (glibenclamide) is a sulfonylurea derivative that is very widely used in the treatment of type II diabetes mellitus. Currently, there are several pharmaceutical formulations available in Mexico containing this drug, however, very limited information about their bioavailabilities is known. The purpose of this study was to compare the bioavailability of two formulations of glyburide used in Mexico, Daonil and Gen-Glybe. Twenty-four Mexican healthy volunteers participated in this study that was carried out following the recommendations of the Declaration of Helsinki. Subjects received a dose of 10 mg of glyburide (two tablets of 5 mg) under fasting conditions in two separate sessions using a randomized crossover design with a one week washout period. Plasma samples were obtained at selected times over 24 hours and stored frozen until analyzed. Pharmacokinetic parameters were obtained and values (mean +/- S.E.M.) were as follows: Cmax 273.32 +/- 25.84 versus 294.83 +/- 27.12 ng/ml; tmax 3.03 +/- 0.23 versus 2.87 +/- 0.24 h; and AUC24h 1396.66 +/- 130.18 versus 1557.99 +/- 140.24 ng x h/ml, for Daonil and Gen-Glybe tablets, respectively. Pharmacokinetic parameters were compared using analysis of variance for a cross-over design and ratios of AUC24h and Cmax and 90% confidence intervals were obtained. As confidence intervals did not exceed the limits of acceptance (80--125%) for Cmax and AUC24h, it is concluded that the formulations tested are bioequivalent.