Virtual Bioequivalence Assessment and Dissolution Safe Space Exploration for Fixed-Dose Metformin-Glyburide Tablet Using Physiologically Based Biopharmaceutics Modeling.

Background/Objectives: Fixed-dose combinations (FDCs) hold significant clinical value for the management of hypertension, diabetes and other chronic diseases. However, since the complexity of formulations, generic compounds require both in vitro pharmaceutical equivalence and in vivo bioequivalence (BE) for each active pharmaceutical ingredient (API). Physiologically based biopharmaceutics modeling (PBBM) not only bridges in vitro drug properties to in vivo pharmacokinetics but effectively assesses the impact of formulations on systemic exposure. This study was aimed at developing a PBBM for metformin-glyburide FDC and investigating its clinically relevant quality specifications. Methods: PK-Sim® software (Version 11.3) was used to establish a PBBM for a metformin-glyburide FDC. Sensitivity analysis identified critical parameters and guided design of virtual populations. Subsequently, virtual bioequivalence (VBE) was assessed between both reference and test formulations, and BE-ensuring dissolution space was explored by the change in dissolution characteristics. Results: The in vivo behavior of products was successfully captured by the developed model. Sensitivity analysis indicated that systemic exposure was primarily sensitive to gastrointestinal (GI) pH and transit times. VBE analysis confirmed BE between the reference and test formulations. The dissolution safe space for the FDC was defined as the concurrent achievement of ≥ 50% dissolution within 25 min for metformin and between 35 and 170 min for glyburide, which constituted equivalent specification. Conclusions: The PBBM developed in this study systematically evaluated the VBE of metformin-glyburide FDC, optimized the acceptance criteria for traditional in vitro dissolution testing, and thereby explored its clinically relevant quality specification.