Development and characteristics of temperature-sensitive liposomes for vinorelbine bitartrate.

A novel liposome with temperature-sensitivity for vinorelbine bitartrate (VB) was designed to enhance VB targeted delivery and antitumor effect. Liposomes without drugs were prepared by thin film hydration, and then VB was entrapped into liposomes by pH gradient loading method. The mean particle size of the liposomes was about 100 nm, and the drug entrapment efficiency was more than 90%. Stability data indicated that the liposome was physically and chemically stable for at least 6 months at 4 °C. In vitro drug release study showed that drugs hardly released at 37 °C; while at 42 °C, drugs released quickly. For in vivo experiments, the lung tumor model was established by subcutaneous inoculation of cell suspension on mice, liposomes and free VB were injected i.v. in mice, followed by exposure the tumors to hyperthermia (HT) for 30 min after administration. The ratio of inhibition tumor of temperature-sensitive liposomes group was significantly higher than the normal injection group. Combining temperature-sensitive liposomes with HT enhanced the delivery of VB and, consequently, its antitumor effects. This liposome could potentially produce viable clinical strategies for improved targeting and delivery of VB for treatment of cancer.