FORMULATION DEVELOPMENT AND EVALUATION OF MICROSPHERES OF ANDROGRAPHOLIDE AND RANITIDINE AS GASTRORETENTIVE DRUG DELIVERY SYSTEM

The present study aimed to develop and evaluate a gastroretentive microsphere formulation containing Andrographolide and Ranitidine to enhance therapeutic efficacy and sustained drug release. Pre-formulation studies confirmed the identity, purity, and compatibility of both drugs. Andrographolide was found to be sparingly soluble in water, whereas Ranitidine exhibited good aqueous solubility. UV spectrophotometric analysis established λmax values of 223 nm for Andrographolide and 278 nm for Ranitidine, with a common wavelength of 252 nm suitable for simultaneous estimation. Calibration curves showed excellent linearity (R² > 0.99), validating the analytical method. FTIR studies confirmed the presence of characteristic functional groups without evidence of drug–drug or drug–polymer interactions. Among the five formulations prepared, MSF5 emerged as the optimized formulation, exhibiting the highest entrapment efficiency (90.45%), smallest particle size (193.89 nm), and favorable zeta potential (-25.1 mV), indicating good stability and uniformity. In vitro drug release studies demonstrated a sustained release profile with 97.98% cumulative drug release over 13 hours. Kinetic modeling revealed that the release followed zero-order kinetics and was predominantly diffusion-controlled, as supported by the Higuchi model. Stability studies conducted for 90 days under room and accelerated conditions confirmed the formulation’s physical stability and consistent entrapment efficiency. Overall, the developed microsphere system shows strong potential for gastroretentive drug delivery, improved bioavailability, and enhanced patient compliance.