Evaluation of bioequivalence between a single-capsule formulation of esomeprazole 40 mg and acetylsalicylic acid 325 mg and the monotherapies given separately in healthy volunteers

OBJECTIVE: The aim of this study was to investigate the bioequivalence of a single oral dose of esomeprazole 40 mg and acetylsalicylic acid 325 mg when formulated as a single capsule, relative to the components given as separate monotherapies. METHODS: This was an open, randomized, single-center, single-dose, 2-stage group sequential design, 2-way crossover study (NCT00688428) in 49 healthy adult volunteers (29 women). In each treatment period, subjects received a single dose of esomeprazole 40 mg and ASA 325 mg formulated as a single capsule or as separate monotherapies given in combination. Treatment periods were separated by a washout period of at least 6 days. The bioequivalence of a single-capsule formulation of esomeprazole 40 mg and ASA 325 mg relative to the monotherapies given individually was assessed by the geometric mean ratios of the area under the plasma concentration-time curve (AUC) and observed maximum plasma concentration (Cmax). If the 94% confidence interval (CI) of the geometric mean ratios of AUC and Cmax were within 0.80 - 1.25, bioequivalence would be established. A 94% CI was used to compensate for the multiple analyses of the study design, and to assure that the actual overall confidence level was 90%. RESULTS: The geometric mean ratios of the AUC for esomeprazole 40 mg and ASA 325 mg when administered in the single capsule formulation, relative to the monotherapies were 0.97 (94% CI, 0.90 - 1.04) and 1.04 (94% CI, 1.00 - 1.08). The corresponding mean geometric ratios for Cmax were 0.99 (94% CI, 0.90 - 1.09) and 1.02 (94% CI, 0.92 - 1.13). CONCLUSIONS: Treatment with esomeprazole 40 mg and ASA 325 mg formulated as a single capsule is bioequivalent to the separate monotherapies of esomeprazole 40 mg and ASA 325 mg when given in combination as separately-administered drugs in healthy adult subjects.