Fexinidazole is a potent anti-Trypanosoma agent. Trypanosoma species human protozoan pathogens are responsible for sleeping sickness and Chagas disease. In vivo, fexinidazole is oxidized to sulfoxide and sulfone metabolites that are effective in blocking the progression of the parasitic disease visceral leishmaniasis. The mechanism of action appears to be by reductive activation via an NADH-dependent nitroreductase expressed by the parasites.