Microparticles against leishmaniasis: Advances, challenges, and perspectives in modified drug delivery systems

Leishmaniasis, a neglected disease affecting approximately 12 million people worldwide, manifests in three primary forms: visceral, mucocutaneous, and cutaneous. Conventional treatments are known for their toxicity, high costs, and increasing resistance to parasites, necessitating the development of innovative solutions. Microparticles emerge as a promising strategy, offering controlled and sustained drug release, reduced systemic toxicity, and improved efficacy through targeted delivery to infected macrophages. This review synthesized available evidence, following the Joanna Briggs Institute methodology and PRISMA-ScR reporting guidelines. Searches were conducted in PubMed, Scopus, and Web of Science, focusing on microparticle formulations for Leishmania spp. Of 36 included articles, 21.6% demonstrated the encapsulation of amphotericin B, a second-line drug whose free form causes severe nephrotoxicity. In encapsulated form, amphotericin B exhibited a significant reduction in acute toxicity, enabling higher, safer doses. Poly(lactic acid-co-glycolic acid) (PLGA) was the most used polymer (38.9%), facilitating phagocytosis by macrophages, the primary host cells. Although most formulations used parenteral administration (92.8%), challenges in ensuring microparticle size uniformity highlight the desirability of oral or topical routes. In conclusion, microparticles represent an up-and-coming alternative in leishmaniasis treatment, enhancing drug efficacy while markedly reducing adverse effects. This research opens new perspectives for developing innovative pharmaceutical formulations to overcome the significant limitations of current therapies.