Amoxicillin is a semi-synthetic, orally absorbed, broad-spectrum antibiotic. It is still widely used in the standard eradication treatment of gastric and duodenal ulcers, which are associated with Helicobacter pylori infection, combined with a second antibiotic and an acid-suppressing agent (1, 2). H. pylori, a prevalent human-specific pathogen, is a causative agent in chronic active gastritis (3), gastric and duodenal ulcers (4) and gastric adenocarcinoma (5), one of the most common forms of cancer in humans. The mechanisms by which H. pylori may cause gastroduodenal disease and contribute to gastric carcinogenesis are still hypothetical.Treatment of H. pylori remains a challenging proposition. One reason for incomplete eradication of H. pylori is probably the short residence time of the dosage form in the stomach so that effective antimicrobial concentration cannot be achieved in the gastric The purpose of the present study was to design mucoadhesive chitosan microspheres containing amoxicillin. Chitosan microspheres with a small particle size and good sphericity were prepared by a spray-drying method followed by chemical treatment with a chemical crosslinking agent (glutaraldehyde). Parameters affecting the crosslinking extent of the crosslinking time and the concentration of the crosslinker agent. Crosslinked spray-dried chitosan microspheres were analyzed for their morphological aspects, particle size, drug entrapment efficiency, swelling percent and in vitro drug release. Batch M4 with a drug polymer ratio of 1:2, dissolved in minimum concentration of acetic acid solution treated with glutraldehyde, was found to be optimal giving controlled drug release for 10 h. It was found that both the increase of glutaraldehyde concentration and crosslinking duration decreased the swelling capacity of chitosan microspheres. This could be directly correlated to drug release from the microspheres.

In this work a different type of formulation, as disc, containing a selected mucoadhesive polymer, fillers, and binders were investigated for their potential as a mucoadhesive gastroretentive delivery system to deliver famotidine in the stomach. Various types of hydrophilic diluents were evaluated for their swelling and mucoadhesive property and one (polyvinylpyrrolidone, PVP) was selected to combine with the selected mucoadhesive polymer (polyethylene oxide, PEO). Discs with different ratios of PEO and PVP were prepared and evaluated for swelling, dissolution, and mucoadhesion. The swelling property of the discs increased as the concentration of PEO was increased and also did the mucoadhesion. These discs retained their integrity and adherence onto gastric mucosa for more than 10h under in-vitro conditions. The PEO, in combination with PVP, yielded a non-disintegrating type mucoadhesive dosage form which was suitable for gastroretentive applications to achieve the desired release profile of the drug.