Adriamycin entrapped in sulfatide-containing liposomes.

Sulfatide-containing liposomes composed of PC, cholesterol, and sulfatide in a molar ratio of 7:2:1 entrapped ADM most efficiently among the negatively-charged liposomes tested. A unilamellar vesicle entrapped 123 ADM molecules, of which 6 molecules are localized in the internal space of the vesicle, 4 molecules are embedded into the membrane matrix, and 113 molecules are bound to the inner surface of the liposomal membrane. Highly efficient entrapment of ADM by the liposomes seems to be due to their rigidity. By the experiment using ovarian tumor-bearing nude mice, it was found that the liposome-entrapped ADM was maintained at much higher blood level, at lower concentration in the heart, and at higher concentration in the tumor than the free drug. The antitumor activity of the liposome-entrapped ADM was comparable with that of the free drug. The body weight of the animals was not affected by the former, whereas it was drastically decreased by the latter.