Combining two technologies: Multifunctional polymers and self-nanoemulsifying drug delivery system (SNEDDS) for oral insulin administration

The aim of the study is to develop a self-nanoemulsifying drug delivery system (SNEDDS) based on thiolated chitosan for oral insulin administration. The preparations were characterized by particle size, entrapment efficiency, stability and drug release. Serum insulin concentrations were determined after oral administration of all formulations. Insulin SNEDDS formulation was served as control. The optimized SNEDDS consists of 65% (w/w) miglyol 840, 25% (w/w) cremophor EL, 10% (w/w) co-solvents (a mixture of DMSO and glycerol). The formulations in the presence or absence of insulin (5 mg/mL) were spherical with the size range between 80 and 160 nm. Entrapment efficiency of insulin increased significantly when the thiolated chitosan was employed (95.14 ± 2.96%), in comparison to the insulin SNEDDS (80.38 ± 1.22%). After 30 min, the in vitro release profile of insulin from the nanoemulsions was markedly increased compared to the control. In vivo results showed that insulin/thiolated chitosan SNEDDS displayed a significant increase in serum insulin (p-value = 0.02) compared to oral insulin solution. A new strategy to combine SNEDDS and thiolated chitosan described in the study would therefore be a promising and innovative approach to improve oral bioavailability of insulin.