[Liposomes as carriers of lipophilic cytosine arabinoside and fluorodeoxyuridine derivatives. Their cytostatic effect and possibilities of tumor cell specific therapy].

A method of preparation for large volumes of sterile, homogenous bilayer liposomes as carriers of lipophilic cytostatic prodrugs is described. Liposomes in the size range of 60 to 120 nanometers are produced through the dialysis of lipid/prodrug/detergent micelles by means of a capillary dialysis system. The cytostatic effect of cytosine arabinoside (ara-C) prodrug liposomes against L1210 leukemia showed to be superior to free ara-C treatment in respect to drug dosage and treatment schedule. Fluorodeoxyuridine (FUdR) prodrug-liposomes were active against various solid tumors, although with less pronounced effects, but at 20-60 times lower drug concentrations as compared to free FUdR. To further improve the cytostatic effect of such prodrug-containing liposomes, methods for the linkage of tumor-cell-specific antibodies to the liposomes are discussed. The targeted delivery of cytostatic drugs by such means might improve their antitumor effects and reduce the untoward toxic side-effects.