Floating drug delivery system is an approach to prolong gastric residence time, thereby targeting site-specific drug release in the upper gastro intestinal tract (GIT) for local or systemic effects. This drug delivery system not only prolongs GI residence time but does so in an area of the GI tract that could maximize drug reaching its absorption site (intestine) in solution form and hence ready for absorption. Metformin hydrochloride, a BCS class III drug has absolute bioavailability of is 50–60% orally administered up to 2.5 g/day in three separate doses and the main site of its absorption is proximal small intestine and also has relatively short plasma elimination half life of 4 to 6.2. Gastric floating drug delivery matrix systems of metformin HCl are designed by direct compression using natural hydrophilic matrix forming polymer, almond gum and sodium bicarbonate as gas generating agent are employed. The powder blend in all the formulations showed good flow characteristics. Of various formulations F1 to F8 , formulation F8 containing 500 mg of Metformin HCl sustained drug release over a period of 10 hours with 96.62 % in 0.1 N HCl ( pH 1.2) and the results compared with the other hydrophilic matrix polymers which are existing polymers for sustained drug release formulations such as HPMC K 50 and Ethyl cellulose K4 included in sustained release formulations F6 and F7, studies conducted in phosphate buffer pH 6.8 and compared with drug release from formulation containing almond gum alone as a hydrophilic matrix polymer.
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