Preclinical evaluations of Norcantharidin liposome and emulsion hybrid delivery system with improved encapsulation efficiency and enhanced antitumor activity

Norcantharidin (NCTD) has a certain degree of hydrophilicity and poor lipophilicity, and has some side-effects, including short t1/2, vascular irritation, cardiotoxicity, and nephrotoxicity, which bring difficulties for formulation research. In this study, we aim to develop a novel nanocarrier to improve encapsulation efficiency, increase sterilization stability, and enhance antitumor activity.Phospholipid complexes methods were used for increasing the lipophilicity of norcantharidin (NCTD), then NCTD phospholipid complexes were not only loaded in the oil phase and oil-water interface surface, but also encapsulated in phospholipid bilayers to obtain NCTD liposome-emulsion hybrid (NLEH) delivery system. The in vitro cytotoxicity and apoptosis, in vivo tissue distribution, tumor penetration, heterotopic, and orthotopic antitumor studies were conducted to evaluate therapeutic effect.NLEH exhibited an improved encapsulation efficiency (89.3%) and a better sterilization stability, compared to NCTD liposomes and NCTD emulsions. NLEH can achieve a better antitumor activity by promoting absorption (1.93-fold), prolonging blood circulation (2.08-fold), enhancing tumor-targeting accumulation (1.19 times), improving tumor penetration, and increasing antitumor immunity.The liposome-emulsion hybrid (LEH) delivery system was potential carrier for NCTD delivery, and LEH could open opportunities for delivery of poorly soluble anticancer drugs, especially drugs that are more hydrophilicity than lipophilicity.