Objective To prepare enteric-coated insulin-chitosan complex nanoparticles(EICCN),and characterize the physicochemical properties,in
vitro release behavior and hypoglycemic effects in diabetic rats.Methods ICCN were formulated through ionic cross linking method,and then enteric-coated by HP55.Their particle size and zeta potential were measured by Coulter Delsa 440 SX and Coulter LS Series,respectively.The entrapment efficiency of insulin was calculated through determining the concentration of insulin in the supernatant after centrifugation.The release behavior in PBS with pH value of 1.2 and 7.4 were studied.The hypoglycemic effects in diabetic rats were investigated.Results The nanoparticles were homogenous and well global.The particle size and zeta potential of nanoparticles with or without enteric coating were((281±)10) nm and(328±13) nm,(30.4±6.97) mV and(33.7±6.69) mV,respectively.The entrapment efficiency of insulin were 78.5% and 74.3%,respectively.The formation of complex between insulin and chitosan reduced the burst release magnificently and the release rate of insulin in EICCN was much more slowly than that in ICCN.Both ICCN and EICCN could effectively decrease the serum glucose levels in diabetic rats and the hypoglycemic effects could maintain for more than 20 h.The enteric coating could increase the
hypoglycemic effect of the nanoparticles significantly.And the relative bioavailability of ICCN and EICCN were 11.12% and 16.29%,respectively.Conclusions Because the EICCN could increase the entrapment of insulin,inhibit the burst release of insulin and enhance the hypoglycemic effect in diabetic rats,they could be useful carrier for the
oral administration of insulin.