FORMULATION AND EVALUATION OF SUSTAINED RELEASE MATRIX TABLETS OF RIOCIGUAT BY USING DIFFERENT POLYMERS

The present study was aimed at the formulation and evaluation of sustained release (SR) matrix tablets of Riociguat using different polymers to prolong drug release and enhance therapeutic efficacy. Riociguat, a soluble guanylate cyclase stimulator indicated for pulmonary hypertension, requires controlled drug delivery to maintain steady plasma concentrations over an extended period. Sustained release matrix tablets were prepared by direct compression method employing various polymers such as Sodium alginate, Chitosan, and HPMC K15M in different ratios to modulate the drug release profile. A total of nine formulations (F1–F9) were developed and evaluated for pre-compression and post-compression parameters. The pre-compression parameters including angle of repose, bulk density, tapped density, Carr’s index, and Hausner’s ratio indicated good flow properties of the powder blend, all within Indian Pharmacopoeia (IP) limits. The post-compression parameters such as weight variation, hardness, thickness, friability, and drug content were found to be within acceptable IP limits, confirming the suitability of the formulation process. In vitro dissolution studies were carried out for 12 hours to assess the drug release profile of all formulations. Among the nine formulations, F2 was considered the optimized formulation as it exhibited a sustained and controlled drug release of 99.58% over 12 hours. The release kinetics suggested that the drug release followed a diffusion-controlled mechanism with polymer matrix swelling contributing to sustained action. The study concludes that sustained release matrix tablets of Riociguat can be successfully formulated using Sodium alginate, Chitosan, and HPMC K15M, and the optimized formulation (F2) demonstrated desirable physicochemical characteristics and extended drug release, making it a promising candidate for once-daily sustained release therapy. Keywords: Riociguat sustained Release Tablets, Sodium alginate, Chitosan, and HPMC K15M