Insulin-loaded alginate/chitosan nanoparticles produced
by ionotropic pre-gelation/polyelectrolyte complexation, provided
markedly enhanced intestinal absorption of insulin
following oral administration. Nanoparticles lowered serum
glucose levels of streptozotocin-induced diabetic rats at
insulin doses of 50 and 100 IU/kg up to 59 and 55%
respectively, of their basal glucose level. The hypoglycemic
effect and insulinemia levels were significantly higher than
that obtained from oral insulin solution and physical mixture
of oral insulin and empty nanoparticles, revealing two to four
fold improvement of oral relative PA. In addition, the
physiological effect was observed for more than 18 h. The
mechanism of insulin absorption seems to be a combination
of both insulin internalization, probably through vesicular
structures in enterocytes and insulin-loaded nanoparticle
uptake by Peyer patches. Alginate/chitosan nanoparticles
appear promising as an oral delivery system for insulin and
potentially for other therapeutical proteins.