Liposils: An effective strategy for stabilizing Paclitaxel loaded liposomes by surface coating with silica

The present work aims at improving stability of paclitaxel (PTX) loaded liposomes by its coating with silica on the surface by a modified sol-gel method. Effect of various components of liposomes such as phosphatidylcholine to cholesterol ratio (PC:CH), PTX and stearylamine on entrapment efficiency (% EE) and particle size were systematically investigated and optimized using central composite design on Design-Expert®. The optimized liposomes were utilized as a template for silica coating to prepare surface coated PTX liposils. Physical stability of liposomes and liposils was evaluated with Triton X-100 and the results indicated that liposils were much more stable as compared to liposomes and the same has been reiterated in stability study performed over 6 months. In vitro cytotoxicity study on B16F10 tumor cells showed cytotoxicity of PTX liposils was not significantly different than PTX liposomes, whereas both were less cytotoxic as compared to the commercial Taxol®. In vivo pharmacokinetics on rats, exhibited increased T_1/2 of liposils when compared to liposomes and Taxol®, thus releasing the drug over a longer duration. The enhanced physicochemical stability as well as controlled release of PTX in liposils developed in this study could be an effective alternative to Taxol® and PTX liposomes.