ABSTRACT:
The sustained release drug delivery system provides essential therapeutic concentration for desired period of time. The drugs having low biological half-life are suitable candidates to be developed in the SR dosage form. Oral osmotic drug delivery is independent of pH, food condition in the stomach, agitation and other variables providing zero order drug release profile leading to predictable plasma profiles. In this study we optimized the oral osmotic tablets using metoprolol succinate having biological half -life of 2-6 hours and bioavailability of 12%. The effect of drug:osmogen ratio was studied. The core tablets were prepared using sodium chloride as osmotic agent and compressed at a weight of 250 mg using 8 mm standard biconcave punches. The dibutyl phthalate, diethyl phthalate, triethyl citrate, castor oil were used as plasticizers. The PEG 400 was used as pore former. The effect of drug osmotic agent ratio, coating thickness in terms of coating weight gain, amount of plasticizers, and amount of pore former were studies as the important variables affecting the drug release. The tablet coating was carried out using cellulose acetate with plasticizer dibutyl phthalate and pore former PEG 400. The formulation consisting of drug and osmotic agent in 1:1.5 ratio, coating weight gain of 2 %w/v, 20 %w/v dibutyl phthalate, 20 %w/v PEG 400 of cellulose acetate concentration with 2 %w/v coating weight gain has shown zero order release profile.