Antitumor Effect of Liposome‐entrapped Adriamycin Administered via the Portal Vein

We examined the distribution in tissues and antitumor effect of freeze‐dried liposome‐entrapped adriamycin (Lipo‐ADM) administered via the portal vein to rabbits bearing VX2 tumors. Liposomes composed of egg phosphatidylcholine (cholesterol 50 mol%) were used as drug carriers. The liver concentration of ADM increased after delivery and cardiac uptake decreased compared with free drug treatment. The in vivo antitumor effect of Lipo‐ADM was determined in rabbits inoculated with VX2 tumor. Repeated injections of free ADM via the portal vein prolonged the life span of tumor‐bearing rabbits. The life span was further prolonged by Lipo‐ADM treatment compared with the control group and the free ADM group. Histological examination revealed that the damage to the liver caused by Lipo‐ADM administered via the portal vein did not differ from that observed in animals treated with free ADM. These results indicate that portal vein administration of Lipo‐ADM may be more effective in dealing with liver metastases than treatment with free ADM and may be therapeutically useful without toxic side effects.