The use of drug delivery systems may reduce the toxicity and improve the activity of antileishmanial compounds. In view of such a strategy, we loaded the antileishmanial agent
pentamidine on
polymethacrylate nanoparticles. The activity of
pentamidine-loaded nanoparticles was compared with that of free
pentamidine in a BALB/c mice model of
visceral leishmaniasis induced by Leishmania infantum. On day 0, mice were infected intravenously with 10(7) promastigotes and then treated via the tail vein on days 14, 16 and 18 with bound
pentamidine, free
drug or isotonic saline (control group). On day 21, liver parasite burdens were evaluated using the Stauber method. Livers and spleens were removed and weighed. Effective doses (ED) were determined using the Michaelis-Menten representation relating the percentage of parasite suppression to the dose. The ED50 of bound
pentamidine was six times lower than that of free
pentamidine (0.17 mg kg-1 vs 1.06 mg kg-1). The ED90 value calculated for bound
pentamidine was 1 mg kg-1. It was not possible to obtain the ED90 for free
pentamidine because the dose-response curve reached a plateau near 60% of parasite suppression. A significant decrease in liver and spleen weights, probably reflecting the leishmanicidal activity, was observed for treated mice with bound
pentamidine. These results showed that bound
pentamidine was more potent than the free
drug against L. infantum in our BALB/c mice model.