A new oral self-emulsifying drug delivery system improves the antileishmania efficacy of fexinidazole in vivo

[Display omitted] •Fexinidazole-loaded self-emulsifying drug delivery systems (FEX-SEDDS) were developed.•SEDDS formed nanoemulsions with small and homogeneous globules after dilution.•No evidence of injury to the intestinal mucosa induced by oral FEX-SEDDS.•Oral SEDDS reduced the parasite burden in Leishmania infantum-infected animals.•They can be a promising oral alternative for the treatment of leishmania visceral. The aim of this study was to develop, characterize and evaluate the in vivo oral efficacy of self-emulsifying drug delivery systems (SEDDS) containing fexinidazole (FEX) in the experimental treatment of visceral leishmaniasis (VL). The developed FEX-SEDDS formulation presented as a clear, yellowish liquid, with absence of precipitate. The droplet size, polydispersion index and zeta potential after dilution in water (1:200) was of 91 ± 3 nm, 0.242 ± 0.005 and −16.7 ± 0.2, respectively. In the simulated gastric and intestinal media, the FEX-SEDDS had a size of 97 ± 1 and 106 ± 9 nm, respectively. The FEX retention in droplet after SEDDS dilution in simulated gastrointestinal media was almost 100 %. Antileishmanial efficacy studies showed that FEX-SEDDS was the only treatment able to significantly (p