Thermosensitive Liposomes Encapsulating Anti-Cancer Agent Lomustine, and Contrast Medium Iohexol, for Thermochemotherapy: Preparation, Characterization, and In Vivo Evaluation.

Abstract

Thermosensitive liposome-based drug delivery systems (DDS) are powerful tools for site-specific delivery of chemotherapeutics, especially when combined with regional hyperthermia. The objective of this work was to develop a novel thermosensitive liposomal DDS loaded with lomustine, a chemotherapeutic compound, and iohexol, a contrast medium for visualization by CT. Thermosensitive compound liposomes (TSCLs) composed of DPPC were prepared by reverse-phase evaporation and investigated for encapsulation efficiency, temperature-sensitivity, release kinetics, and In Vivo pharmacokinetics. The size and zeta-potential of TSCLs ranged from 250 to 300 nm and -15 to -30 mV, respectively. At 41 °C, TSCLs were shown to release over 90% of iohexol and lomustine within 4 h. The in vitro release profiles of iohexol and lomustine at 41 °C conformed to first-order kinetics and Weibullmodel, respectively. Phase-transition did not occur after incorporation of cholesterol and soybean phospholipids. In Vivo evaluation performed with C6 glioma model rats proved the prolonged half-lives and improved bioavailability by liposomal encapsulation for both compounds under mild local hyperthermia. The TSCLs used in this study may offer a clinically promising mean of increasing efficacy and controlling toxicity.