Combination therapy with nitazoxanide and amphotericin B, Glucantime (R), miltefosine and sitamaquine against Leishmania (Leishmania) infantum intracellular amastigotes

Leishmaniasis is a neglected disease that affects poorest population mainly in developing countries, representing one of the major causes of mortality and morbidity. Therefore, efforts to find new chemotherapeutics for leishmaniasis remain a priority. Previous reports demonstrated the in vitro and in vivo antileishmanial activity of nitazoxanide, an antiprotozoan agent used in the treatment of infectious diarrhea. The present work was carried out to determine the effect of nitazoxanide in combination with current antileishmanial drugs. Mouse peritoneal macrophages were infected with Leishmania(Leishmania)infantum amastigotes in order to calculate the 50% and 90% inhibitory concentration values. Drug interactions were assessed with fixed ratio isobologram method and fractional inhibitory concentrations (FIC50 and FIC90); sum of FIC (Sigma FIC50 and Sigma FIC90) and overall mean Sigma FIC (x Sigma FIC50 and x Sigma FIC90) were calculated for each combination. The nature of interactions was classified according to the x Sigma FIC50 and x Sigma FIC90. The combination between nitazoxanide and amphotericin B, Glucantime (R), miltefosine and sitamaquine showed x Sigma FIC50 values of 1.13, 0.83, 1.06 and 0.94, respectively, indicating additive interaction. Considering the in vitro activity of nitazoxanide and the obtained results, further in vivo studies may be considered to evaluate possible drug interactions in visceral leishmaniasis. (C) 2013 Elsevier B.V. All rights reserved. (AU)