Design and evaluation of pH-sensitive omeprazole enteric-coated pellets IP for sequential release in the gastrointestinal tract

Omeprazole, a widely used proton pump inhibitor, is highly unstable under acidic conditions, resulting in degradation in the stomach and reduced therapeutic effectiveness. This study aimed to develop pH-sensitive enteric-coated pellets of omeprazole (7.5% w/w) for sequential drug release within the gastrointestinal tract. The formulation was designed to protect omeprazole from acidic degradation during gastric transit and facilitate controlled release within the intestinal region. Extrusion-spheronization was used to prepare the pellets, followed by coating with an HPMC barrier layer and an enteric coating of Eudragit L100/S100. Three formulation batches with varying polymer concentrations and coating levels were prepared and evaluated to identify the optimal formulation. The prepared formulations were characterized for micromeritic properties, drug content, dissolution behavior, and preliminary accelerated stability. The dissolution studies demonstrated minimal drug release in acidic medium (pH 1.2) for up to 2 hours, followed by controlled drug release exceeding 95% in pH 6.8–7.4 buffer media. Among all formulations, F2 exhibited the most desirable performance, demonstrating effective acid resistance, uniform drug distribution, and controlled drug release in the intestinal medium. Preliminary accelerated stability studies indicated no significant changes in physical appearance or drug release characteristics during the study period. The developed pH-sensitive pellet system successfully achieved sequential drug release and demonstrated satisfactory stability, indicating its potential as a promising oral delivery approach for acid-labile drugs such as omeprazole.