New approach for oral administration of insulin with polyalkylcyanoacrylate nanocapsules as drug carrier.

Polyalkylcyanoacrylate nanocapsules (mean size 220 nm), composed of spheric polymeric structures, have been used as a drug carrier for insulin. The rate of encapsulation of insulin is 54.9%, and we studied the therapeutic efficiency of the nanocapsules in diabetic and normal rats. When administered subcutaneously, insulin-loaded nanocapsules prolonged the hypoglycemic effect of insulin; the duration of this effect increased with the doses. When administered orally by force-feeding to diabetic rats, insulin nanocapsules (12.5, 25, and 50 U/kg) decreased fasted glycemia 50-60% by day 2. This effect was maintained for 6 or 20 days with 12.5 or 50 U/kg, respectively. Only the dose of 100 U/kg decreased fed glycemia by 25% in diabetic rats. In normal rats, hyperglycemia induced by an oral glucose load was reduced by 50% with the same dose of oral insulin nanocapsules. We concluded that polyalkylcyanoacrylate nanocapsules preserve the therapeutic effect of insulin when administered orally and prolong this effect when administered subcutaneously and orally.