Formulation and Evaluation of Multilayer Matrix Tablet of Captopril forOral Controlled Delivery

The current study aimed to develop an oral controlled drug delivery system for captopril, a highly water-soluble drug. Captopril is a highly water-soluble drug if not formulated properly may release the drug immediately and cause toxicity. Half-life of captopril is around 2-3 hours with 60-75% of bioavailability and prescribed thrice a day, due to this reason an attempt was made to prepare multilayer matrix tablet of captopril for its controlled and durable release. Multilayer matrix tablets of captopril were prepared by compressing 100mg of guar gum granules containing either 60%(T1), 70%(T2) and 80%(T3) of guar gum on both sides of matrix powder of captopril containing either 1:2, 1:1 and 2:1 ratio of HPMC and ethyl cellulose, above which an immediate release layer is compressed having the loading dose of captopril forming the fourth layer of the multilayered matrix tablet. The respective formulations were coded as T1M1, T1M2, T1M3, T2M1, T2M2, T2M3, T3M1, T3M2 and T3M3. Result: Values for bulk densities, tapped density, compressibility, Hausner ratio and angle of repose for all the prepared powder and granules were found in a range of 0.33 to 0.446, 0.37 to 0.50, 8.002 to 16.27, 1.08 to 1.16 & 25.96 to 27.7 respectively. Whereas, values for thickness, friability, hardness, Weight variation and content uniformity is found to be 7.14±0.27 to 7.29±0.22, 0.15 to 0.33, 5.7±0.28 to 5.9±0.27, 645.4±2.9 to 649.5±4.7 & 97.79±0.52 to 101.12±0.50 respectively. Swelling study indicates the % swelling of the polymers and the study reviles that maximum swelling were obtained with the formulation T3M3. Dissolution profile defines that the concentration of polymer plays an important role in the release of drug. The values of drug release for the formulation T1M1 to T3M3 after 12 hours were found to be in between 68.91 to 96.47 % respectively.