Novel cosolvent systems for nifurtimox: improving solubility, trypanocidal efficacy, and stability

Abstract

Aim: This study aimed to evaluate a range of cosolvents and their mixtures as liquid vehicles to enhance the solubility and trypanocidal efficacy of nifurtimox.Materials and methods: Several pharmaceutical-grade solvents were screened for their ability to solubilize nifurtimox. The cytotoxicity of selected cosolvent systems was assessed and analyzed using the hemolysis assay. The stability of nifurtimox in these systems was studied under various temperature conditions. The trypanocidal activity of nifurtimox formulated in cosolvent systems was tested against Trypanosoma cruzi trypomastigotes by determining the drug concentration required to lyse 50% of the parasite population.Results: Nifurtimox solubility increased from 0.2 mg/mL in water to 23.5 mg/mL in selected cosolvent systems. Hemolytic assays indicated acceptable cytotoxicity profiles for the most promising formulations, supporting their suitability for further development. Trypanocidal studies demonstrated that these systems effectively inhibited or killed Trypanosoma cruzi trypomastigotes. Stability studies confirmed that nifurtimox solutions remained chemically stable, with no precipitation and consistent drug content at all tested storage temperatures.Conclusion: Cosolvent-based delivery systems enhance the solubility of nifurtimox while maintaining adequate trypanocidal activity against Trypanosoma cruzi and demonstrating acceptable stability and safety profiles. Thus, these formulations represent a promising strategy to improve the therapeutic effectiveness of nifurtimox.