Effects of intraperitoneal administration of liposomes and methods of preparing liposomes for local therapy.

Many different methods of preparing liposomes exist, but the biological and physical properties of these preparations are not known. We therefore investigated the physical properties of liposomal doxorubicin (DOX) and found it to be most effective when administered intraperitoneally for carcinoma in the abdominal cavity. Liposomal DOX was prepared in three ways, by the Bangham method (BLDOX), pH gradient method, and gelation method. We investigated the physical properties of each preparation. And then we investigated the effects of the liposomes and liposomal lipids on the uptake of DOX by carcinoma cells in vitro and on the survival of Ehrlich ascites carcinoma-bearing mice in vivo. The uptake of DOX by the cells differed significantly with each liposome in vitro. The physical properties of the liposomes, including liposomal membrane lipids, size, zeta potentials and fluidity of liposomal membrane, were not so different, but the leak level of entrapped DOX from the liposomes was. Furthermore, the survival of ascites tumor-bearing mice also differed with each liposome preparation, DMPC containing BLDOX being the most effective when administered intraperitoneally. The method of preparation is an important factor affecting the properties of liposomes, and for local therapy, DMPC containing BLDOX is most effective because of its leaky property.