Antifungal efficacy of terbinafine and itraconazole co-encapsulated in polycaprolactone nanoparticles in a murine model of subcutaneous sporotrichosis

• Grant number: 25/02793-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: July 01, 2025
• End date: April 30, 2027
• Field of knowledge: Health Sciences - Pharmacy
• Principal Investigator: Kelly Ishida
• Grantee: Alex Borges Samuel
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Sporotrichosis is a subcutaneous mycosis caused by species of the genus Sporothrix, primarily transmitted through traumatic inoculation via contact with contaminated soil and plants, as well as zoonotic transmission from infected cats, whose epidemiological relevance has been increasing. The disease presents various clinical forms, with cutaneous and lymphocutaneous manifestations being the most common, requiring antifungal treatment since self-healing is rare. The species S. brasiliensis is predominant in South America and Brazil, where outbreaks of the disease have been reported in several states, with a significant increase in human and feline cases in recent decades, leading to its compulsory notification starting in 2025. Treatment options include itraconazole, terbinafine, potassium iodide, and amphotericin B, which have limitations such as low solubility, toxicity, and drug interactions. To overcome these challenges, polymeric nanoparticles, such as those made of polycaprolactone (PCL), have emerged as a promising alternative, improving bioavailability, skin permeation, and antifungal efficacy. This project aims to co-encapsulate itraconazole and terbinafine in PCL nanoparticles and evaluate their antifungal activity in a murine model of cutaneous sporotrichosis. PCL polymeric nanoparticles will be obtained through the nanoprecipitation technique for the co-encapsulation of ITC and TRB. The nanoparticles will be characterized in terms of their average diameter, polydispersity, and zeta potential and subjected to stability studies over different periods. Morphological characteristics will be defined using electronic microscopy. Quantitative methods obtained through High-Performance Liquid Chromatography will be used to determine encapsulation efficiency and in vitro drug release. Porcine ears will serve as a skin model to evaluate the influence of the nanocarrier on the skin barrier and the cutaneous penetration of ITC and TRB. To assess toxicity and anti-Sporothrix activity, Galleria mellonella larvae will be infected with S. brasiliensis yeasts and treated with ITC, TRB, and PCL-ITC/TRB. Treatment evaluation will be based on survival curves, health indices, fungal burden, and histopathological analysis. The assessment of antifungal efficacy in murine models will be conducted in mice infected with S. brasiliensis yeasts and treated with different PCL-ITC/TRB regimens. Infection progression will be monitored, and fungal burden and organ histopathology will be evaluated. Analyses will be performed using statistical software, with p-values < 0.05 considered significant.