Development and Characterization of Innovative Nifurtimox Formulations as Therapeutic Alternative for Chagas Disease

Chagas disease, caused by <i>Trypanosoma cruzi</i>, remains a neglected tropical disease with limited and often suboptimal chemotherapeutic treatment options. The WHO recommends nifurtimox (NFX) for treating Chagas disease, which, although it is effective in the early stages of infection, has variable efficacy in the chronic phase and induces adverse effects that frequently compromise the continuity of the treatment. This study focused on the development and characterization of innovative lipid-based self-emulsifying drug delivery systems (SEDDSs) and poly(ε-caprolactone) implants containing NFX. The SEDDS formulations modified the NFX release extent and rate. The implant characterization included thermal analysis, X-ray diffraction, thermo-optical analysis, and scanning electron microscopy, confirming the low interaction between NFX and the polymer. In vitro assays demonstrated the enhanced anti-<i>T. cruzi</i> activity of the NFX-SEDDS, with minimal cytotoxicity in mammalian cells. In vivo studies using <i>T. cruzi</i>-infected mice revealed that both formulations effectively suppressed parasitemia, achieving cure rates comparable to those of the standard oral NFX treatment. Additionally, the implants showed improved tolerability and sustained efficacy, delivering a prolonged effect equivalent to 40 oral doses. These findings highlight the potential of these innovative NFX formulations as promising alternatives for treating Chagas disease, particularly in the chronic phase, offering improved adherence and comparable efficacy to the existing therapies.