Formulation and Evaluation of Gastroretentive in Situ Gelling System of Saxagliptin

Gastroretentive floating In-situ gel refers to a polymer solution of low viscosity which upon coming in contact with the gastric fluids; undergoes change in polymeric conformation and a viscous strong gel of density lower than the gastric fluids is produced. The gelation can be triggered by temperature modulation, pH change, and ionic crosslinking. Insitu gels can be administered by oral, ocular, rectal, vaginal, injectable and intra-peritoneal routes. Moreover presence of CaCl2 shows significant increase in gel strength, the degree of rigidness of gel increases due to increasing degree of crosslinking of divalent Ca2+ ions with the polymer chains. The CaCl2 which upon contact with 0.1N HCl (pH 1.2) the liquid polymeric solution should undergo a rapid sol-to-gel transition by means of ionic gelation. The composition of gastric fluid is rich in Cl- ions; hence on interacting with CaCl2 as cross-linking agent, in-situ gel formed rapidly.The in-situ gel formed should preserve its integrity without dissolving or eroding so as to localize the drug at absorption site for extended duration. In-vitro and buoyancy study test gave a good indication about the gastroretentive property of the selected formula (F3) in the activity of drug and it agreed with the in-vitro results and the proposed mathematical modeling for release kinetics.