Preparation, characterization and in vivo evaluation of pH-sensitive oral insulin-loaded poly(lactic-co-glycolicacid) nanoparticles

Aim: Oral administration of insulin is a promising drug delivery system for diabetic patients as it is convenient and reduces pain, two of the major contributors to non-compliance. Methods: In this study, insulin was encapsulated in poly(lactic-co-glycolicacid) (PLGA) nanoparticles (NPs) by using double-emulsion/ solvent evaporation technique and analyses on its release kinetics were carried out using both in vitro and in vivo methods. Results: First, only by this simple methods, release speed of insulin from NPs can be controlled in different pH solution. The rate of release of insulin was found to be slower in acidic pH; about 90% of insulin was released in 11 days at pH 1.0. In alkaline conditions, the release was faster; about 90% release was observed to occur within 3 days at pH 7.8. The insulin-loaded poly (lactic-co-glycolicacid) nanoparticles (PINPs) were administered orally to diabetes mellitus-induced rats and the response of blood glucose and insulin levels was estimated. Blood glucose decreased and the concentration of insulin in animal blood increased. In diabetic animals which were administered intermittent insulin, every 8 h, blood glucose levels were maintained equivalently with those of healthy rats. Conclusion: These experimental results indicated that oral PINPs are able to deliver insulin effectively and decrease animal blood sugar; in conclusion, this may be a promising delivery system for the treatment of diabetes.