Bioequivalence of two brands glipizide tablets

Abstract

The present study was carried out to evaluate bioequivalence between two brands of glipizide tablets. In -vitro tests revealed that both brands met the specified criteria of the United States Pharmacopoeia 27 specifications according to identification, uniformity of dosage units, assay and dissolution test, indicating pharmaceutical equivalence. The dissolution profiles of a generic product and an innovator’s product were similar based on model independent method. Comparative bioavailability of the two brands was conducted in healthy Thai male volunteers using randomized replicated crossover design with 1 week washout period between treatments. After an orally single dose administration, serial blood samples were collected for 12 hours and plasma concentrations of glipizide were determined by high performance liquid chromatography. Relevant pharmacokinetic parameters of the two brands were calculated from plasma glipizide concentration-time profiles and compared using analysis of variance. Results showed that there were no statistically significant differences (p>0.05) in area under the plasma drug concentration-time curve (AUC) and peak plasma drug concentration (C[subscript max]) based on log-transformed data, including other pharmacokinetic parameters with respect to formulation effect of both products. The 90% confidence intervals for the ratios of mean log-transformed data of a generic product relative to an innovator’s product of AUC[subscript 0-12], AUC[subscript 0-∞]and C[subscript max] were within 80-125%. Difference of t[subscript max] means was 20.45%. This indicated that the two brands tested were bioequivalent regarding to the rate and extent of absorption. Pharmacokinetic parameters found in this experiment agreed and closed to those previously reported.