The objective of this research work was to enhance solubility and dissolution profile of acyclovir. Nanocrystals were prepared by an anti-solvent precipitation process supplemented by sonication using different stabilizers. The formed nanocrystals were of 376-1085 nm in size. Formulations NC7 and NC8 showed marked improvement in dissolution compared to pure drug, thus greater bioavailability. These nanocrystals were further utilized for the preparation of floating tablet. The nanocrystals based floating tablets were prepared by direct compression technique using different release retardants polymers such as HPMC K100M and carbopol 934P, sodium bicarbonate as gas generating agent in floating sustained release layer. The friability (0.20 to 0.38 %), weight variation (1.17-1.63%) and drug content (96.07 to 98.74 %) of different batch of tablets were found within prescribed limits. The swelling index of tablets composed of carbopol 934P was higher than tablet containing HPMC K100M. The buoyancy lag time was largely dependent on sodium bicarbonate concentration and found to be less than 3 minute for all the optimized tablets (F5, F11 and F13) and was not affected by the polymeric concentrations. The total floating time for different formulations was in the range of 12-30 hours. Release profiles indicated that, increasing the polymer concentration has drastically retarded the release of acyclovir. The optimized tablets F5, F11 and F13 showed 97.47%, 94.57% and 98.83% drug release at the end of 24 hours. Tablets followed non-fickian diffusion controlled first order kinetics. During the stability period selected tablets were found to be stable with respect to physico-chemical and drug release characteristics. Acyclovir pure drug has low solubility and low permeability. The nanocrystal formulation enhances the saturation solubility which increases the dissolution rate and thereby systemic absorption.
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