Relative enhancement by various liposomes of BCNU effectiveness against L-1210 leukemia in vivo.

When maximal effective dose (MED) of BCNU is injected together with liposomes to mice with L-1210 leukemia, the effectiveness of the drug is decreased. But when half the MED is injected with liposomes into such mice, survival is increased compared to mice injected with BCNU alone. Study of liposome composition on BCNU anti-leukemic effect revealed that negatively charged liposomes made of dioleylphosphadyl choline plus phosphatidyl serine given with half the MED of BCNU increased both long-term survival and mean survival time. This enhancement was not produced with negatively charged liposomes made of dioleylphosphatidic acid alone or in liposomes in which phosphatidyl serine plus dioleylphosphatidic acid was diluted with the neutral phospholipid, dioleylphosphatidyl choline.