ABSTRACT:
Cilnidipine is a dihydropyridine calcium channel blocker used in the management of hypertension. Its oral therapeutic performance may be affected by poor aqueous solubility, variable bioavailability and the need for sustained plasma drug levels during long-term antihypertensive therapy. The present study aimed to develop and evaluate gastroretentive floating tablets of Cilnidipine using HPMC K100M as a release-retarding polymer and sodium bicarbonate with citric acid as an effervescent gas-generating system. Tablets were prepared by direct compression and optimized using a 3² factorial design, where HPMC K100M concentration and sodium bicarbonate concentration were selected as independent variables. The prepared batches were evaluated for pre-compression parameters, tablet quality attributes, floating behavior, drug content uniformity, in vitro drug release and accelerated stability. All powder blends showed acceptable micromeritic properties suitable for compression. Tablets complied with pharmacopeial requirements for weight variation, hardness, thickness and friability. The optimized formulation F6, containing 100 mg HPMC K100M and 40 mg sodium bicarbonate, showed bulk density of 0.28 g/mL, tapped density of 0.36 g/mL, angle of repose of 23.2°, Carr’s index of 22.2% and Hausner ratio of 1.28. F6 exhibited drug content of 99.6%, friability of 0.30%, total floating time of 12 h and sustained drug release of 89% at 12 h. Stability testing under accelerated conditions for three months showed only minor changes in hardness, friability, drug content, floating time and drug release. The findings indicate that HPMC K100M-based gastroretentive floating tablets can provide prolonged gastric residence and sustained release of Cilnidipine, making the optimized batch a promising once-daily oral formulation for hypertension management..