Design and evaluation of bilayer floating tablets of amoxicillin trihydrate

Abstract

The present investigation concerns the development and evaluation of floating tablets of amoxicillin trihydrate which, after oral administration, are designed to prolong the gastric residence time and increase drug bioavailability. Bilayer floating tablets comprised two layers, immediate release and controlled release layers. The immediate release layer comprised sodium starch glycolate as a super disintegrant and the controlled release layer comprised HPMC K4M, K15M and SCMC as release retarding polymers. Sodium bicarbonate was used as a gas generating agent. The controlled layer was compressed and granules of the immediate release layer were added to it then both layers were compressed using a single station rotary press. Direct compression method was used for formulation of the bilayer tablets. The release of amoxicillin trihydrate was found to follow a mixed pattern of Korsmeyer-Peppas release model. The tablets were evaluated for hardness, friability, Drug content uniformity, swelling index, and in vitro drug release. Final formulation released approximately 87% drug in 12 h in vitro, while the floating lag time was 20 min, because of prompt disintegration of the fast releasing layer and the enhanced rate of dissolution of amoxicillin trihydrate from the system. Final formulation followed the Korsemeyer-Peppa’s model and showed no significant change in physical appearance, drug content, floatability or in vitro dissolution pattern after storage at 40°C/75% RH for three months.