Lipid nanoparticles for amphotericin delivery in the treatment of American tegumentary leishmaniasis.

Leishmaniasis occurs in the five continents and represents a serious public health challenge, but is still a neglected disease, and the current pharmacological weaponry is far from satisfactory. Triglyceride-rich nanoparticles mimicking chylomicrons (TGNP) behave metabolically like native chylomicrons when injected into the bloodstream. Previously we have shown that TGNP as vehicle to amphothericin B (AB) for treatment of fungi infection showed reduced renal toxicity and lower animal death rates compared to conventional AB. The aim of the current study was to test the tolerability and effectiveness of the TGNP-AB preparation in a murine model of Leishmania amazonensis infection. The in vitro assays determined the cytotoxicity of TGNP-AB, AB, and TGNP in macrophages and promastigote forms and the leishmanicidal activity in infected macrophages. The in vivo toxicity tests were performed in healthy mice with increasing doses of TGPN-AB and AB. Then, animals were treated with 2.5 mg/kg/day of AB, 17.5 mg/kg/day of TGNP-AB, or TGNP three times a week for 4 weeks. TGNP-AB formulation was less cytotoxic for macrophages than AB. TGNP-AB was more effective than AB against the promastigotes forms of the parasite and more effective in reducing the number of infected macrophages and the number of amastigotes forms per cell. TGNP-AB-treated animals showed lower hepatotoxicity. In addition, TGNP-AB group showed a marked reduction in lesion size on the paws and parasitic load. The TGNP-AB preparation attained excellent leishmanicidal activity with remarkable lower drug toxicity at very high doses that, due to the toxicity-buffering properties of the nanocarrier, become fully tolerable.