Formulation of solid dosage forms to overcome gastric pH interaction of the factor Xa inhibitor, BMS-561389.

Purpose: The purpose of the study was to investigate the specific mechanism by which elevated gastric pH reduces the absorption of BMS-561389, a factor Xa inhibitor, and to develop a solid formulation strategy to overcome this gastric pH interaction.

Methods: A dissolution method in an acetate buffer at pH 5.5 was used to evaluate the dissolution behavior of the tablet formulation. A precipitation model was used to screen different excipients for their potential to minimize the pH-dependent absorption of BMS-561389. Excipients that showed promise in the precipitation model were incorporated in modified tablet formulations. Dissolution rate of the modified tablets was also determined by the acetate buffer method. A canine model for pH-dependent absorption was subsequently used to evaluate the tablet formulations.

Results: Dissolution studies suggested that the reduced absorption of the original formulation was the result of the precipitation of the poorly water-soluble free base during the initial dissolution of the salt. Modified tablets containing organic acids, sulfobutylether-beta-cyclodextrin, or povidone showed enhanced dissolution as compared with the original formulation. Drug absorption from the tablet containing tartaric acid was substantially independent of gastric pH in the canine model.

Conclusion: A multitier approach was successful in identifying a solid dosage form that minimizes the pH-dependent absorption of this drug candidate.