In Vitro and In Vivo Evaluation of Floating Microspheres of Prazosin Hydrochloride

The concept in the development of controlled oral release floating dosage forms is not just to prolong the delivery of drugs but also to prolong the presence of dosage forms in the stomach in order to improve the bioavailability of drugs with a 'narrow absorption window'. Prazosin hydrochloride is a selective α-1-adrenergic receptor antagonist used to treat hypertension. It has a mean plasma half -life of 2-3 hour.Prazosin has a shorthalflife and low bioavailability in the upper part of the GIT hence it is suitable for gastro-retentive system. In the present study, an antihypertensive drug, Prazosin hydrochloride, is delivered through a gastroretentive microparticulate system capable of floating on simulated gastric fluid for 24 h. Microspheres are prepared by solvent evaporation technique. Microspheres showed excellent buoyancy and a controlled release pattern with 24h. Showed 99.87% drug release at the end of 24 hours. In vivo bioavailability studies performed on albino rats and Tmax, Cmax, AUC and Kel were calculated and confirmed significant improvement in bioavailability. The data obtained thus suggests that floating microspheres can be successfully designed to give controlled drug delivery, improved oral bioavailability.