RESUMO
Promethazine is currently used for its antipsychotic and ansiolytic effects. It is a phenothiazine with anticalmodulin action, not toxic for human beings at therapeutic dosis. The present results show that promethazine has trypanocidal effect on both epimastigote and trypomastigote stages of T. cruzi; two hundred muM inhibited epimastigote growth in culture medium and 2 muM immobilized and killed bloodstream trypomastigotes. When promethazine (55 mg/Kg/day) was used as treatment of T. cruzi infected mice, it proved effective in reducing parasitemia and it increased the survival of treated animals. Ultrastructural studies suggest that the lethal effect of this phenothiazine is related to a detergent effect that disrupts T. cruzi cell membrane.