The distribution of doxorubicin in mice following administration in niosomes.

Large multilamellar non-ionic surfactant vesicles (niosomes) with diameters of around 800-900 nm prepared from a C16 triglyceryl ether with and without cholesterol and containing doxorubicin (Adriamycin) were administered to S180 tumour-bearing NMRI mice by bolus injection. Although in-vitro drug release from cholesterol-containing niosomes is delayed, in-vivo there was little difference between the two preparations when plasma levels were compared. As previously observed, half-lives of the drug were prolonged compared with free solution profiles. Liver uptake was not significantly affected by niosome encapsulation of doxorubicin. There is minor accumulation of drug in the lung, perhaps because of aggregation of the vesicles and their physical entrapment. Tumour levels of drug were higher following administration of cholesterol-containing niosomes and this was reflected in the more effective reduction in tumour growth. Metabolism of doxorubicin is altered by niosomal administration, but more studies are required before the significance of the metabolic data can be assessed.