APPLICATION OF LIPID MICROSPHERES FOR THE TREATMENT OF CANCER

Lipid microspheres can act as a carrier for antitumor agents. We incor porated a lipophilic antitumor agent, 1,3-bis(2-chloroethyl)-1-nitroso urea (BCNU) into microspheres by homogenizing a soybean oil solution o f BCNU with egg yolk lecithin. Lipid microsphere-encapsulated BCNU sho wed a significantly enhanced antitumor activity with reduced toxicity in mice with L1210 leukemia when compared to the corresponding dose of free BCNU. Lipid nanospheres, smaller particles containing BCNU with an average size of 50 nm, also showed a similar level of in vivo antit umor activity. An in vitro study showed that [C-14]triolein uptake by tumor cells was increased by incorporation into microspheres. The in v itro uptake of small microspheres was lower than that of standard micr ospheres. However, the in vivo half-life of small microspheres was lon ger, they avoided capture by the reticuloendothelial system and showed higher accumulation at tumor sites. Thus, lipid microspheres may be u seful for delivering various lipophilic chemotherapy agents.