The present study concerns the preparation and evaluation of gastroretentive expandable tablets of Losartan potassium, which enhance the gastric residence time and bioavailability after oral administration. Losartan potassium drug is a class of drug called as angiotensin receptor blockers (ARBs). It works by relaxing blood vessels, so that can flow more easily, systemic hypertension. Formulations were prepared using various polymers HPMC K4M, Sodium Carboxy Methyl Cellulose, Carbopol 934NF, Methyl cellulose by direct compression method. Various formulation batches were evaluated for various parameters like weight variation, thickness, hardness, friability, swelling index, drug content and in-vitro drug release. The study has revealed that the swelling and release rate from tablets depends on type and concentration of polymer. Formulations with the codes F8 and F12 could only keep the drug's release continuing for 12 hours. Formulation F8 was chosen for animal testing based on tablet performance, drug release, and kinetics. There was a significant increase in t_1/2 of pure drugs and prepared formulation. This indicates that the residence time of drug administered as expandable tablets was increased significantly.

KEYWORDS: Losartan potassium, Gastro retentive, HPMC K4M, Sodium Carboxy Methyl Cellulose, Carbopol 934NF, Methyl cellulose