Formulation design and in vitro Evaluation of Floating tablets of an Antiulcer drug using Different Synthetic and Natural polymer

Famotidine is a histamine H2-receptor antagonist and it is widely prescribed in gastric and duodenal ulcers, ZollingerEllison syndrome and gastroesophageal reflux disease (GERD) but susceptible to metabolism by colonic bacteria, which in turn has ramifications for drug delivery and absorption. Thus, it is logically way to improve the therapeutic efficacy of the drug if the gastric residence time of the dosage form is increased at the absorption site. Moreover, the drug is highly soluble in aqueous environment, it is necessary to reduce/controls the drug release from the formulations. Therefore, the main aim of this research was to formulate controlled-release floating tablets of Famotidine in an effort to prolong its residence time in the stomach. The drug and polymer compatibility was studied by subjecting physical mixtures of drug and polymers to FTIR spectroscopy. Five batches of tablets were prepared by using HPMC K 100M and Hibiscus mucilage in different concentrations along with gas generating agent sodium bicarbonate. The Tablets were prepared by direct compression technique. The natural polymer was isolated and extracted from leaves of Hibiscus rosa-sinensis in our laboratory and that is used as a polymer in combination with HPMC K 100M to prepare floating tablets. The prepared floating tablets were evaluated for weight variation, hardness, thickness, friability, drug content uniformity, buoyancy lag time, total floating time and in vitro dissolution studies. Results were found that hardness 4-5kg/cm and friability test was found to less than 1% in all the cases. Drug content ranging from 96.13 to 99.67% and the % drug release was in the order of F1> F2> F3> F4> F5. It reveals that increase the Hibiscus mucilage concentration decrease the release of Famotidine from floating tablets and it was showed that the Hibiscus mucilage exhibit excellent retarding effect on drug release from the floating tablets. Among the formulations studied, formulation F3 showed optimum release characteristics. The release mechanisms and the drug release rate kinetics of the tablets were examined using in vitro dissolution testing model. The drug release from all the formulations followed Peppas model and the ‘n’ value of F2, F3 and F4 was found to be between 0.5 – 1.0 indicates anomalous/non-fickian type (diffusion and erosion) of release mechanism except formulation F5 followed Zero order kinetics and showed super case II transport mechanism (i.e., n = 1.449). The ‘n’ value of F1 was found to be 0.36 indicates fickian type of release mechanism. Stability study was carried out for optimized formulation F3 at 40 0 C/75% RH for 30 days. The results of stability studies revealed no significant change in physical appearance; hardness and drug content indicating the formulation was stable.