Prazosin Hydrochloride, a selective alpha-adrenergic receptor blocking agent, was loaded in the hollow microspheres to improve bioavailability and patient compliance by prolonging the residence time in the gastrointestinal tract. The hollow microspheres of Prazosin HCl were prepared by solvent evaporation diffusion method using Eudragit RS 100 and ethyl cellulose as a release controlled polymer, HPMC as a matrix former. The present study involves preparation and evaluation of floating microspheres with Prazosin Hydrochloride as model drug for prolongation of gastric residence time. Prazosin Hydrochloride is a BSC class-II having short biological half-life (2 to 3 hours) with low bioavailability (40-60%). The sustain release gastro retentive dosage form offer many advantages for Prazosin Hydrochloride drug. Gastro retentive dosage form improves the bioavailability and reduces the side effect of Prazosin hydrochloride. The microspheres were prepared by the emulsification solvent diffusion method using polymers Eudragit RS100, Hydroxypropylmethyl cellulose K4M and Ethylcellulose. The shape and surface morphology of prepared microspheres were characterized by optical microscopy. In-vitro drug release studies were performed and drug release kinetics was evaluated using the linear regression method
