POTENCIAL ATIVIDADE DE FÁRMACOS COMBINADOS SOBRE FORMAS EPIMASTIGOTAS DE Trypanosoma cruzi.

Abstract

Chagas disease, caused by the protozoan Trypanosoma cruzi, represents a major health risk in Latin America. Current treatments, benznidazole and nifurtimox, are limited by significant side effects and toxicity. To find better solutions, drug repositioning has become a promising approach. Recent research, based on in silico findings and subsequent tests, shows that oxiconazole nitrate and lansoprazole are effective in vitro against the epimastigote forms of T. cruzi Dm28c, sparking interest in exploring their combined effects, as well as their association with benznidazole. This study evaluated the in vitro effect of the combination of oxiconazole nitrate with lansoprazole and benznidazole on epimastigote forms of Trypanosoma cruzi. Experimental research using in vitro tests was conducted with a clonal population of the T. cruzi Dm28 strain. The study assessed the efficacy of the combinations by testing multiple proportions. Cell viability was measured after 72 hours of incubation with drug combinations using a colorimetric method with MTS and PMS. Based on the obtained results, the Combination Index and Dose Reduction Index were determined for the combinations. The cytotoxicity of the drug combinations on animal cells was determined through MTT assay, and the Selectivity Index of the combinations was calculated. In the viability assay with MTS, oxiconazole nitrate showed an IC50 of 91.1 μM, benznidazole had an IC50 of 23.5 μM, and lansoprazole showed no effect on cell viability. The combination of oxiconazole nitrate:lansoprazole presented the following results for each proportion: 1:3 IC50 15.1 μM, 1:1 IC50 49.6 μM, and 3:1 approximately 45.7 μM. Differences in IC50 were also observed in the different combinations of benznidazole:oxiconazole nitrate, with the following results: 1:3 IC50 52.2 μM, 1:1 IC50 19.7 μM, and 3:1 IC50 7.1 μM. All proportions of the oxiconazole nitrate:lansoprazole combination showed a synergistic effect, while in the oxiconazole nitrate:benznidazole combination, proportions with antagonistic and synergistic effects were observed. The Dose Reduction Index calculation verified that lansoprazole was capable of reducing the concentration of oxiconazole nitrate by more than 28 times, and the combination of benznidazole and oxiconazole nitrate reduced the concentration of benznidazole by approximately 13 times at all inhibitory concentrations. The combination of oxiconazole nitrate and benznidazole showed high cytotoxicity, while the combination of oxiconazole nitrate with lansoprazole presented lower cytotoxicity than the isolated drugs in two of the three proportions, enabling the establishment of an effective treatment regimen with fewer side effects, which may increase patient adherence and consequently improve treatment success rates. Additionally, the results demonstrate the potential to reduce drug doses when used in combination. This analysis contributes to the discovery of new effective therapeutic associations for the treatment of Chagas disease.