Captopril, an effective anti hypertensive drug, faced various limitations in preparation of sustained or controlled delivery system due to the fact that the drug is not stable in intestine. Thus the objective of the present study was to prepare gastro retentive microspheres using poly methacrylate polymers to retain the drug in the stomach for longer period. Microspheres prepared by solvent evaporation method were analyzed to sustain the release of captopril in gastric region. The drug and polymer compatibility analysis were done to determine possible interactions between them using FTIR, DSC and TG analysis. The compatible polymers were selected for further formulations. Microspheres of captopril were prepared using Eudragit RLPO, RL100, RSPO and RS100 and its combinations. The process was optimized for the drug polymer ratio, speed of rotation and concentration of surfactant. The various parameters such as percentage yield, drug content, buoyancy percentage, particle size analysis and bulk density was determined. The in vitro release study was carried out for the prepared microspheres. The bulk density of the microspheres were less than one and the results of buoyancy showed that the prepared microspheres float in the acidic medium upto 8h.The microspheres gave sustained release of drug upto 24h. The kinetic modeling showed that release follows first order and the mechanism was by both dissolution and diffusion. Thus the formulation and in vitro evaluation of captopril loaded microspheres using eudragit polymers found to retain in the gastric region upto 8 h and the drug release was also found to sustained upto 24h.
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