Repaglinide and Metformin-Loaded Amberlite Resin-Based Floating Microspheres for the Effective Management of Type 2 Diabetes

Background: Low bioavailability of anti-diabetic drugs results in the partial absorption of the drug as they are mainly absorbed from the stomach and the lower part of the GIT. Drug bioavailability of anti-diabetic drugs can be significantly increased by prolonging gastric retention time through gastro-retentive dosage form such as floating microspheres. Objective: The study was aimed to develop and characterize resin based floating microspheres of Repaglinide and Metformin for superior and prolonged maintenance of normoglycaemia in type-2 diabetes mellitus. Methods: Repaglinide and metformin were complexed with amberlite resin; later resin complexed drug was encapsulated in Ethylcellulose floating microspheres. Floating microspheres were characterized for morphology, particle size, IR spectroscopy, DSC, in vitro release and buoyancy studies. Further, floating microspheres were tested for in vivo blood glucose reduction potential in Streptozocin- induced diabetic mice. Results: Floating microspheres had a spherical shape and slightly rough surface with the entrapment efficiency in a range of 49-78% for metformin and 52-73% for repaglinide. DSC studies revealed that no chemical interaction took place between polymer and drugs. Floating microspheres showed good buoyancy behavior (P<0.05) and prolonged drug release as compared to plain drug (P<0.05). The blood glucose lowering effect of floating microspheres on Streptozocin induced diabetic rats was significantly greater (P<0.05) and prolonged (#131;12h) and normoglycaemia was maintained for 6hr. Conclusion: Floating microspheres containing drug resin complex were able to prolong drug release in an efficient way for a sustained period of time; as a result, profound therapeutic response was obtained.