Evaluation of Parenteral Depot Insulin Formulation using PLGA and PLA Microparticles

PLGA and PLA microparticles entrapping insulin are prepared by solvent evaporation method and are evaluated in diabetes-induced rat for its efficacy in maintaining blood sugar level from a single intramuscular dose. In vitro release of insulin from PLGA and PLA microparticles are 75.35 ± 1.73% and 67.536 ± 2.23%, respectively in 168 h (7 days). Released insulin from polymer particles are mostly in monomeric form without aggregation. Optimal use of stabilizers during particle formulation helps in reducing protein denaturation and thus results in stabilized insulin-loaded polymer particles. Intramuscular administration of insulin-loaded PLGA (50 : 50) and PLA microparticles (equivalent to 25 IU insulin/kg of animal weight) in alloxaninduced diabetic rats result in 53.86 ± 4.2% and 39.52 ± 6.7% reduction in blood glucose level, respectively in 96 h. This effect continued up to 7 days in case of PLGA and PLA microparticles.