Novel sodium tauroursodeoxycholate-based multifunctional liposomal delivery system for encapsulation of oleanolic acid and combination therapy of type 2 diabetes mellitus

Liposomes have demonstrated great potential for drug delivery and diabetes treatment. However, hydrolysis by enzymes and emulsification by endogenous bile salts make liposomes unstable in the gastrointestinal tract. In this study, sodium tauroursodeoxycholate (TUDCNa)-based multifunctional bilosomes were designed to address the deficiencies of conventional liposomes. In the designed bilosomes, cholesterol was replaced by TUDCNa, which served as both a membrane stabilizer and an antidiabetic drug. Oleanolic acid (OA) was encapsulated in both conventional liposomes (OA-Ch-Lip) and bilosomes (OA-Tu-Bil) to compare their properties. Firstly, OA-Tu-Bil exhibited similar encapsulation efficiency and drug loading compared to OA-Ch-Lip, but with a smaller particle size. Secondly, OA-Tu-Bil showed better stability than OA-Ch-Lip. Thirdly, bilosomes exhibited prolonged intestinal retention time and improved permeability and oral bioavailability. Fourthly, in type 2 diabetes mellitus (T2DM) mice model, TUDCNa synergized with OA to exhibit the strongest therapeutic effect. In conclusion, TUDCNa have demonstrated the ability to substitute cholesterol in conventional liposomes, it provided a new approach for oral delivery of hypoglycemic drugs, and offered an innovative strategy for combination therapy.