Micronucleus formation in bone marrow of mice treated with nifurtimox or benznidazole.

A single nifurtimox administration to male mice orally (p.o.) (600 - 2000 mg/kg) but not intraperitoneally (i.p.) was able to increase micronucleus formation in bone marrow significantly. No significant increase in micronucleus formation in the bone marrow of mice treated with benznidazole at dosages up to 2000 mg/kg, either p.o. or i.p., was observed. The potential mutagenic risk of nifurtimox treatment in patients suffering from Chagas' disease is analyzed.