Lectin Conjugated Gastro-retentive Microspheres of Amoxicillin for Effective Treatment of Helicobacter pylori

Abstract

Helicobacter pylori mainly exists deep inside the gastric mucosae and adheres to epithelial cells of the stomach. In the present work, concanavalin-A (Con-A) conjugated gastro-retentive microspheres of amoxicillin trihydrate (AMT) were formulated and thoroughly evaluated. Eudragit S100 microspheres were prepared by emulsion solvent diffusion method and characterized for micromeritic properties, per cent drug entrapment, per cent yield, surface morphology, buoyancy behaviour and in vitro drug release in simulated gastric fluid. The microspheres were then conjugated with Con-A and conjugation was verified by IR spectroscopy and differential scanning calorimetry. Moreover, Con-A conjugated microspheres were further characterized for zeta potential, mucoadhesiveness to gastric mucosae and Con-A conjugation efficiency. The microparticles were found to be regular and spherical in shape with a size range 106.4-192.4 μm depending on drug to polymer ratio (1:1 to 1:3). All the microsphere formulations showed noteworthy drug entrapment from 62.3% to 70.2%. In vitro floating test clearly showed that most of the microspheres were floating even after 12 h of testing period. Zeta potential of optimized formulation and Con-A conjugated microspheres was found to be 5.6 and 18.7 mV respectively. Attachment of lectin to the Eudragit microspheres significantly increases the muco-adhesiveness (83.7%) compared to non-conjugated microspheres (16.7%) and also controlled the release of drug in simulated GI fluids. The results suggest that these carriers can be used to incorporate other antibiotic agents and could provide better therapeutic effect against H. pylori infection.