Nanostructured lipid carriers for oral treatment of leishmaniasis: design and preclinical evaluation

Pentavalent antimonials are the primary treatment for leishmaniasis due to their proven efficacy and cost-effectiveness. However, they present poor oral absorption, parenteral administration, and serious adverse effects due to prolonged use. Nanostructured Lipid Carriers (NLC) offer a promising solution, providing prolonged release, enhanced intestinal permeability, and oral bioavailability. This study aimed to address these issues by developing Nanostructured Lipid Carrier loaded with meglumine antimoniate (NLC-MA) for oral leishmaniasis treatment. We used design of experiments (DoE) for optimization. The chosen NLC-MA was characterized assessing size, polydispersity index (PdI), zeta potential (ZP), entrapment efficiency (EE), pH, and by analytical techniques such as DSC, FTIR, XRD, and TEM. Stability under simulated gastrointestinal conditions, in vitro release kinetics, cytotoxicity in RAW 264.7 macrophages, and leishmanicidal activity were assessed. NLC-MA presented 41.13nm, PdI 0.227, ZP -27.9mV, EE of 62.43%, and pH 5.23. Characterization techniques confirmed drug incorporation and nanoparticles with reduced crystallinity. TEM images showed spherical morphology. NLC remained stable in gastrointestinal pH and under refrigeration storage, while lyophilized formulations retained their initial properties. MA release from NLC followed the Peppas-Sahlin model, an anomalous transport mechanism. Importantly, MA showed no cytotoxicity in macrophages, but the NLCs exhibited cytotoxicity beyond 50µg/mL. NLC-MA displayed improved efficacy against L. infantum. Overall, these results highlight the potential of utilizing a lipid nanocarrier incorporating meglumine antimoniate as an innovative drug delivery platform for oral treatment against leishmaniasis.