A NOVEL SUSTAINED-RELEASE FORMULATION OF INSULIN, WHICH INITIAL RAPID RELEASE IS DRAMATICALLY ATTENUATED

摘要

To assure a strictly controlled release of insulin, the preparation method for insulin-loaded microcapsules was developed. Microcapsules were prepared with injectable, biodegradable polymer composed of co-poly (D,L-lactic/glycolic) acids (PLGA)(Mean molecular weight;6,600 (6k) L/G ratio;50:50), which main diameter was 15～30 μm. When insulin-loaded PLGA (insulin content; about 3%) were just once subcutaneously given to streptozotocin-induced hyperglycemic rats (250 U/kg), plasma insulin concentration increased and the levels to show hypoglycemic effects were maintained. When some additives were used through the preparation procedure, the initial burst was dramatically decreased. From the results of plasma insulin levels obtained from administration to diabetic rats, the ratio of AUCO-24h/AUCO-336h was calculated to be 9.7～13.0%. In while, the formulation without any additives bursted the insulin so rapidly that the ratio of AUCO-24h/AUCO-336h was 57.6%.