Emerging role of vesicular carriers for therapy of visceral leishmaniasis: conventional versus novel.

Visceral leishmaniasis (VL) is a systemic protozoan infection that infects a million people living in subtropical and tropical areas. Drugs are the major treatment available against this fatal infection. Conventional chemotherapy of VL involves treatment with pen- tavalent antimonials, pentamidine, paromomycin, miltefosine, etc., but this treatment is challenging because of the failure of drugs to penetrate macrophages where the parasite hides, toxic side effects, and drug resistance due to incomplete treatment schedules. The newer therapeutic approach of combination therapy employing multi-drug combinations provides improved treatment of VL because the combination reduces length of treatment, relapse, and risk of toxicity and increases the therapeutic index. Although considerable success has been attained using combination therapies, none has yet achieved commercial status. Therefore, there is an urgent need of designing novel, site-specific leishmanicidal drug carriers for safe and effective management of VL. Colloidal carriers such as liposomes, niosomes, emulsomes, and their engineered versions offer superior therapeutic efficacy over the conventional treatment in terms of site-specific drug delivery related to absolute treatment of disease with reduced side effects and toxicity. The control over spatial and sequential distribution of drug molecules after systemic or localized administration represents the major dispute in drug-delivery systems, and this can be resolved by the use of these colloidal carriers. The present review describes current conventional and combination drug therapies with special consideration given to the emerging role of novel vesicular colloidal carriers designed against VL. Colloidal carriers employing drugs in combination could lead to reductions in the duration of conventional treatment, better patient compliance, and the prevention of anti-leishmanial drug resistance or toxicity.