Antimonial treatment of hamsters infected with leishmania (viannia) panamensis: Assessment of parasitological cure with different therapeutic schedules

The objective of the study was to establish the effective dose and route of administration of Glucantime® for treating hamsters infected with Leishmania (Viannia) panamensis and to use this model to test new treatment regimens to attain clinical and parasitological cure. In the first experiments animals were inoculated subcutaneously in the hind foot with 5 × 10⁶ promastigotes of L. panamensis (HOM/COL/84/1099) from a 6 d culture. One month after inoculation, Glucantime® was administered intramuscularly (i.m.) at 20, 40 or 60 mg/kg/d for 20 d to groups of hamsters. Only 60 mg/kg/d resulted in both clinical improvement and parasite elimination from the skin and draining lymph node. In the second set of experiments, i.m., local and combined antimonial regimens were compared. The local regimen, of 4 intralesional (i.l.) injections of 4 mg of antimony at 5 d intervals, and the combined regimen (i.m. and i.l.), were more efficient at clearing parasites than the systemic (i.m.) schedule, especially when a low dosage of Glucantime® (30 mg/kg/d × 20 d) was used. The results suggest that combining local treatment and low systemic dosages of antimonials results in clearance of L. panamensis.