PREPARATION AND CHARACTERIZATION OF SUPERPOROUS HYDROGELS AS GASTRORETENTIVE DRUG DELIVERY SYSTEM FOR ATENOLOL

Gastro-retentive drug delivery system can retain the drug in the gastric region for several hours which enhances drug release and improves bioavailability. Atenolol, an antihypertensive drug has a short half-life, limited bioavailability, highly unstable at basic pH and is extensively absorbed from the stomach. These features triggered the need for developing the gastro-retentive system. In the present study, a superporous hydrogel was developed as a gastro-retentive drug delivery system. Chitosan/poly (vinyl alcohol) interpenetrating polymer network (IPN) type superporous hydrogels were prepared using a gas foaming method employing glyoxal as the cross-linking agent. Sodium bicarbonate was used as a foaming agent to introduce the porous structure. Swelling behaviors of the superporous hydrogel in acidic solution were studied to investigate their applications for gastric retention device. The optimum preparation condition of superporous hydrogels was obtained from the gelation kinetics. SPH tablets of atenolol were prepared by direct compression incorporating microcrystalline cellulose, magnesium stearate, talc and sodium bicarbonate, etc. and evaluated. The super porous hydrogels were highly sensitive to pH of swelling media and showed fast swelling and good porosity. SPH tablets of atenolol showed good pre-compressional and post-compressional properties. Formulation IV containing chitosan (160 mg), glyoxal (400 mg) and polyvinyl alcohol (400 mg) exhibited good swelling ratio and sustained release of drug throughout 12 h through gastro-retention. Compatibility studies proved the integrity of the developed tablets. Stability studies indicated that optimized formulation is stable. Thus the superporous hydrogel tablets of atenolol have been successfully prepared with prolonged drug release to enhance bioavailability of the drug.