Encapsulation of an insulin-modified phosphatidylcholine complex in a self-nanoemulsifying drug delivery system (SNEDDS) for oral insulin delivery

Insulin is a dimeric hormone commonly administered by subcutaneous injection as the primary treatment for diabetes. This strategy, while efficient, does carry potential complications i.e., lipodystrophy with a decrease in absorption and also possible infections, caused by constant injectable punctures or lack of hygiene measures at the time of administration. Unfortunately, orally administered insulin has low bioavailability. In the present study we developed a complex based on insulin and modified or unmodified phosphatidylcholine, in order to encapsulate the hormone in a self-nanoemulsifying drug delivery system (SNEDDS) incorporating 2.5% (wt%) of the complex and managing to form nanoemulsions with particle sizes of 20-44 nm. SNEDDS were subjected to in vitro gastrointestinal conditions, showing a 35.7% bioavailability upon reaching the final phase of the simulated small intestine. In an in vivo study, Wistar rats with induced diabetes showed a 36.1% reduction in blood glucose levels after 4 h of administering the modified phospholipid SNEDDS, and a 1.8% bioavailability with respect to the subcutaneous application of insulin.