Luliconazole Potentiates Efficacy of Miltefosine Against <i>Leishmania donovani</i>

Visceral leishmaniasis is a vector-mediated parasitic disease caused by Leishmania donovani. Its treatment relies on chemotherapy with limited options. Existing drugs face significant challenges, including low efficacy, high relapse rates, toxicity, and cost. Therefore, exploring novel chemotherapeutic strategies identified as newer drugs targeting L. donovani CYP51 either alone or in combination with Miltefosine, which presents a promising alternative to current therapy. Here, we have evaluated the antileishmanial potential of an azole drug, luliconazole, which was previously demonstrated to target the sterol biosynthesis pathway in Leishmania major, in combination with conventional antileishmanial agents. Luliconazole exhibited significant inhibitory activity against both extracellular and intracellular L. donovani, with half-maximal inhibitory concentrations of 4.67 and 6.24 µM, respectively. Notably, the addition of miltefosine and luliconazole combinations resulted in a synergistic effect, reducing the effective doses by 3.26- and 5.62-fold compared to monotherapy with miltefosine and luliconazole, respectively. Conversely, the combination of luliconazole with Amphotericin B yielded antagonistic effects. A significant increase in nitric oxide by the parasite-infected macrophages after luliconazole treatment underscores its leishmanicidal potential. Evaluation of host cell cytotoxicity, hemolytic assays, and oxidative burst affirmed the safety of luliconazole. This study is limited to in vitro intracellular amastigote. These findings highlight the efficacy of luliconazole, particularly in combination with miltefosine. Further investigations including formulation development and in vivo validation, are needed to assess the translational potential. This is the first study to demonstrate that luliconazole enhances miltefosine efficacy against L. donovani.