A novel insulin formulation can keep providing steady levels of insulin for much longer periods in-vivo.
We have recently succeeded in preparing insulin-loaded microcapsules that release the insulin in a strictly controlled manner with little initial rapid release in-vitro or in-vivo. We show here the superiority of the best formulation prepared with co-poly(D,L-lactic/glycolic) acids (PLGA) (mean MW 5800, L/G ratio 50:50) with a main diameter of 15 approximately 30 microm in-vivo. When 3.2 % insulin-loaded PLGA microcapsules were subcutaneously given as a single dose to streptozotocin-induced hyperglycaemic rats (250 U kg(-1)), plasma insulin levels gradually increased and constant levels (30.3-94.1 microU mL(-1)) were sustained. Rats receiving the formulation once a week showed not only steady plasma insulin levels, but also gained weight at a similar speed to normal rats. Meanwhile, daily treatment with Humulin U (25 U kg(-1)) caused a transient high insulin level (2723.9 microU mL(-1) at 1 h) in plasma, but the body weight of the rats was little changed. A pharmacological study in female Cynomolgus monkeys also revealed that the microcapsular formulation provided a flat release of insulin for longer periods and showed no immunogenic activity. In the near future, therefore, this insulin formulation could become very beneficial as a provider of basal insulin levels for insulin-dependent diabetic patients.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002214:Capsules; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003692:Delayed-Action Preparations; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006943:Hyperglycemia / Q000188:drug therapy; D007328:Insulin / Q000097:blood / Q000627:therapeutic use*; D008252:Macaca fascicularis; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D002214:Capsules; D003692:Delayed-Action Preparations; D007328:Insulin