ABSTRACT
Benznidazole and nifurtimox-treatments regimens currently used in human are supported by very limited experimental data. This study was designed to evaluate the time and dose dependence for efficacy of the most important nitroheterocyclic drugs in use for Chagas disease. In order to evaluate time dependence, Y strain-infected mice received benznidazole for a total of 1, 3, 7, 10, 20, and 40â¯days. Treatment courses of 3-10-day were effective in clearing parasitaemia and suppressing mortality, but parasitological cure was not achieved. Extending the treatments to 20 or 40â¯days clearly improved benznidazole efficacy. The 20-day treatment induced cure in 57.1% of Y strain infections (partially drug resistant) but failed to cure Colombian strain infections (full drug resistant), while the 40-day treatment resulted in cure of 100% of Y and 50% of Colombian strain infected mice. The increased cure rates in T. cruzi infected animals that received nifurtimox for 40â¯days confirm the relationship between the length of treatment and efficacy. An improvement in efficacy was observed with increasing benznidazole doses; cure was verified in 28.6% (75â¯mg/kg), 57.1% (100â¯mg/kg) and 80% (300â¯mg/kg). Overall, these nonclinical study data provide evidence that the efficacy of benznidazole is dose and time dependent. These findings may be relevant for optimizing treatment of human Chagas disease.
