ATENOLOL AND GLIPIZIDE BILAYER FLOATING TABLETS: FORMULATION AND EVALUATION
Ch. Taraka Ramaro* and G. Lavanya
The FDDS formulations can be used for the medicaments which are absorbed from the stomach as well as intestine. A bilayer tablets contain two layer immediate release layer which release initial dose from system while the another sustained release layer absorbs gastric fluid, forming an impermeable Colloidal gel barrier on its surface, and maintain a bulk density of less than unity and thereby it remains buoyant in the stomach. The effervescent systems include use of gas generating agents, carbonates(ex. Sodium bicarbonate) and other organic acid(e.g. citric acid and tartaric acid) present in the formulation to produce carbon dioxide (CO2) gas, thus reducing the density of system and making it float on the gastric fluid. An alternative is the incorporation of matrix containing portion of liquid, which produce gas that evaporate at body temperature. The non effervescent FDDS based on mechanism of swelling of polymer or bioadhesion to mucosal layer in GI tract. The most commonly used excipients in non effervescent FDDS are gel forming or highly swellable cellulose type hydrocolloids, polysaccharides and matrix forming material such as polycarbonate, polyacrylate, polymethacrylate, polystyrene as well as bioadhesive polymer such as chitosan and carbopol. The Bilayered Floating tablets containing glipizide (anti diabetics) and atenelol (anti hypertensive) were successfully prepared by direct compression method. The physiochemical evaluation results for the powdered blend of all fullfill official limits .The F7 formulation which releases the glipizide in sustained manner in up to 12 hours and Atenelol immediate release F5 formulation showed 100.6% drug release with in 30min. Dissolution of all the tablets prepared followed zero order kinetics with coefficient of determination (R2) values above 0.965. Plots of percent release versus square root of time were found to be linear with R2 0.9877 with all the tablets prepared indicating that the drug release from these tablets was diffusion controlled. FTIR studies were perfmed on drug and the optimized formulation using Shimadzu FTIR (Shimadzu Corp., India) as a result no interactions were observed drug-excipients.
Keywords: Floating tablets, immediate release, Bilayer tablets, Floating lag time, Dissolution.
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