Development of Discriminating and in Vivo Correlating Dissolution Method for BCS Class Ii Cilostazol Immediate Release Tablet Formulation

Cilostazol is used to treat symptoms of intermittent claudication in peripheral vascular disease. It is classified as a Class II drug in the Biopharmaceutics Classification System, exhibiting low solubility and poor bioavailability, which makes pharmacokinetic evaluation essential during product development. This study aimed to develop a discriminative dissolution medium and method reliable for predicting the in vivo results of Cilostazol tablets. In this study, dissolution methods were developed according to regulatory guidelines using water (per USP monograph) and buffer solutions (pH 1.2, 4.5, and 6.8) supplemented with 0.05–0.30% sodium lauryl sulfate (SLS). Testing was performed on a formulated sample and a comparator product (n=12 each) at 37 ± 0.5 °C, with varying paddle speeds (50–75 rpm) and volumes (500–900 mL). The most biorelevant and discriminating condition—a pH 1.2 buffer with 0.05% SLS, 50 rpm paddle speed, and 500 mL volume—was identified as the most suitable in vitro profile for distinguishing the test formulation from the comparator and for predicting in vivo results.