Formulation and Development of Floating Tablet of Highly Water Soluble Drug Using Combination of Hydrophilic and Hydrophobic Polymers

Water soluble drugs if not formulated properly, may release the drug at a faster rate and produce a toxic concentration on administration. Captopril belongs to the class I of biopharmaceutical classification system (BCS) has short half life (~2hrs) shows dose dumping, burst and stability in acidic pH of stomach. In this study HPMC K15M and Compritol 888 ATO alone and in combination different proportions using physical mixture and solid dispersion method to prepare floating matrix tablet. The tablets were evaluated for appearance, weight variation, hardness, friability, floating lag time, duration and integrity of matrices, In-vitro and In vivo drug release kinetics. IR spectra, thermal behavior and X-ray diffraction pattern of selected solid dispersions were carried out indicating no degradative changes. The rate of release of Captopril from floating matrix tablets containing physical mixtures was found to be affected by the concentration of Compritol 888 ATO increase in the concentration decrease the release. Among the formulations containing solid dispersions of drug with Compritol888 ATO (SPC3c’’) give retardation of drug release (t90% >12) for extended time. All formulations indicated diffusion exponent (n) values in the range 0.4 to 0.6 suggesting Fickian diffusion. The values of ‘n’ increased with increase in concentration of lipid polymers suggesting a shift in the mechanism of drug release from Fickian to anomalous. All formulations show initial burst release which may due to high water solubility of Captopril. The X-Ray photographs indicated the residence of tablet in stomach for about 5hs.