Replicate study design in bioequivalency assessment, pros and cons: bioavailabilities of the antidiabetic drugs pioglitazone and glimepiride present in a fixed-dose combination formulation.

An open-label, randomized, 2-sequence, 4-period crossover (7-day washout period between treatment), replicate design study was conducted in 37 healthy subjects to assess intersubject and intrasubject variabilities in the peak (Cmax) and total (AUC) exposures to 2 oral antidiabetic drugs, pioglitazone and glimepiride, after single doses of 30 mg pioglitazone and 4 mg glimepiride, given under fasted state, as commercial tablets coadministered or as a single fixed-dose combination tablet. Variabilities for AUC(infinity) for coadministered and fixed-dose combination treatments were similar: 16% to 19% (intra) and 23% to 25% (inter) for pioglitazone and 18% to 19% (intra) and 29% to 30% for glimepiride (inter, excluding 1 poor metabolizer). Fixed-dose combination/coadministered least squares mean ratios of >or=0.86 and the 90% confidence intervals of these ratios for pioglitazone and glimepiride of between 0.80 and 1.25 for Cmax, AUC(lqc), and AUC(infinity) met the bioequivalency standards. Gender analysis showed that women showed mean of 16% and 30% higher exposure than men for glimepiride (excluding 1 poor metabolizer) and pioglitazone, respectively. There was considerable overlapping in the AUC(infinity) values, making gender-dependent dosing unnecessary. Patients taking pioglitazone and glimepiride as cotherapy may replace their medication with a single fixed-dose combination tablet containing these 2 oral antidiabetic drugs.

RCT Entities:   Population Interventions Outcomes