Synthesis, characterization and antiulcer study of pH-sensitive microspheres

Omeprazole, a proton-pump inhibitor used in peptic ulcers, gastro-esophageal-reflux disorder, Zollinger-Ellison syndrome and in H. pylori infections. The omeprazole is unstable at acidic pH, undergoes degradation in stomach. To prevent the degradation in stomach, dosage forms are supplied as enteric-coated tablets or granules encapsulated in gelatin capsules. The efficiency of such dosage forms depends upon the extent of coating, solubility of coating material; type of dosage form etc. Recently, pH-sensitive polymer are utilized to deliver drug to intestine. The polymer swells only in alkaline pH and releases the drug as it enters the intestine. In this research, pH-sensitive formulations were developed to deliver the omeprazole effectively. Using the stimuli-responsive polyacrylamide-g-sodium alginate polymer, microspheres were prepared by coaservation followed by cross-linking with gluteraldehyde. Omeprazole drug were loaded in microspheres. All microspheres were evaluated for size distribution, content uniformity, in vitro dissolution and pulsatile swelling study. Pharmacological screenings were done for antacid and antiulcer activities of different omeprazole containing formulations. Results indicated that the pH, free acidity, total acidity, and ulcer-index in both non-lighted and ligated ulcer models were comparatively reduced in rats treated with the omeprazole containing pH-sensitive microspheres than enteric-coated granules than neat omeprazole. Thus, developed formulation release was superior in intestine and thus produced superior action.