The effects of topoisomerase I inhibitors on T. cruzi epimastigotes after 72 h of treatment. (a) Topotecan affected cell proliferation especially after using higher drug concentrations. (b) Cell viability of T. cruzi treated with topotecan was reduced in a dose-dependent way after treatment for 48 h. (c) Irinotecan did not cause a significant growth inhibition even after treatment for 72 h. The asterisks indicate drug addition to the culture medium. Data are the average of three independent experiments. DMSO, dimethyl sulfoxide.