The therapeutic effect of sodium stibogluconate in BALB/c mice infected with Leishmania donovani is organ-dependent.

A study of the antileishmanial efficacy of sodium stibogluconate was carried out in BALB/c mice. The drug was administered to Leishmania donovani-infected animals on days 7 and 8 post-infection in one of three forms; free (40-50 mg Sbv Kg-1), liposomal, or niosomal (6.4-8.0 mg Sbv Kg-1) drug. On day 14 post-infection counts of the number of parasites present in the liver, spleen and bone marrow of treated and control animals showed that although all three drug preparations significantly reduced parasite numbers in the liver (approximately equal to 99% suppression) they had little effect on those residing in the spleen or bone marrow. The carrier forms of the drug were therefore significantly more effective than free drug in reducing liver parasite burdens. Increasing the concentration and the number of doses of free drug (maximum of 500 mg Sbv Kg-1), and reducing the size of the vesicles used to deliver the drug had a minimal effect on parasite numbers in the spleen and bone marrow. It is proposed that because of the resistance of spleen and bone marrow parasites to drug therapy, the BALB/c mouse infected with L. donovani provides an excellent model system for the study of drug delivery to these deeper tissue sites.