Preparation and characterization of oral insulin-trimethyl chitosan complex-loaded solid self-nanoemulsifying drug delivery systems (SNEDDS).

Insulin, a pancreatic hormone regulating blood glucose, is available in forms of syringe, pen, or implants; however, these methods presented challenges related to skin adverse reactions and patient compliance. Oral insulin delivery has long been explored due to higher compliance and reduced costs. Similar to natural insulin secretion, but prone to GIT breakdown and low bioavailability. SNEDDS has been investigated to address these in protein formulations. This study formulated Insulin into SNEDDS with trimethyl chitosan and spray-dried for stability, then analyzed for properties and drug release. The study successfully prepared Insulin-TMC SNEDDS with a 36.17±4.02 s emulsification time, forming a Grade B nanoemulsion. Droplet sizes remained nanoscale (134.20-287.20 nm for liquid, 188.77-214.93 nm for solid), preserving characteristics post-spray drying. Stability was confirmed in TMC-free formulations, while TMC variants showed sedimentation over time. TMC-containing Solid-SNEDDS showed moisture content below 5 %, indicating good stability. Insulin release varied with pH-highest at pH 2.5 with 3 mg/mL TMC (105.48 % cumulative percent drug release), while lower releases were seen at pH 6.6 (61.73±1.38 %) and 7.0 (61.73±1.38 %) without TMC. The study supports TMC-based SNEDDS and spray drying as a potential method for oral insulin delivery.