ABSTRACT:
The present study involves preparation and evaluation of floating microspheres of acyclovir as model drug for prolongation of gastric residence time. The microspheres were prepared by emulsion solvent evaporation method using polymers hydroxyl propyl methyl cellulose, ethyl cellulose, eudragit S100 and eudragit RL. The prepared floating microspheres were evaluated for flow properties by calculating the angle of repose, compressibility index and various physicochemical parameters including particle size, incorporation efficiency, in vitro floatability studies, in vitro drug release studies. The shape and surface morphology of prepared microspheres were characterized by optical and scanning electron microscopy. The mean particle size increased with increasing ethyl cellulose concentration and eudragit S 100 concentration in cellulose and eudragit microspheres respectively. The scanning electron microscopy confirms the hollow nature of microspheres with pores on the surface of floating microspheres, which imparts floating properties to the prepared floating microspheres. The mean particle size increased and the drug release rate decreased at higher polymer concentration. The prepared microspheres exhibited prolonged drug release 12 h and remained buoyant. In vitro drug release studies were performed and drug release kinetics was evaluated using the linear regression method. Microspheres were evaluated for drug release was found to follow Higuchi kinetics and the drug release mechanism was found Fickian type. The developed floating microspheres of acyclovir may be used in clinic for prolonged drug release in stomach for at least 12 hrs, thereby improving the bioavailability and patient compliance.