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Nonionic surfactant (NIS) vesicles (niosomes) formed from self-assembly of hydrated synthetic NIS monomers are capable of entrapping a variety of drugs and have been evaluated as an alternative to liposomes. Nystatin (NYS) is a polyene antifungal drug that has been used in the treatment of cutaneous, vaginal and oral fungal infections since the 1950s. The aim of this work is to encapsulate NYS in niosomes to obtain a safe and effective formula administered parenterally for neutropenic patients. NYS niosomes were prepared by the thin-film hydration method using Span 60 or Span 40 and cholesterol (CHOL). Stearylamine and dicetyl phosphate were added as the positive and negative charge-inducing agents (CIA), respectively. Two molar ratios were used, namely NIS/CHOL/CIA (1:1:0.1 and 2:1:0.25). Neutral and positively charged niosomes gave the highest encapsulation efficiencies. NYS niosomes were characterized using transmission electron microscopy, differential scanning calorimetry and dynamic light scattering. The release of neutral and negatively charged NYS niosomes was estimated, and it showed a slow sustained release profile. A 25-kGy γ-irradiation dose was sufficient to sterilize the investigated vesicles. NYS niosomes exerted less nephrotoxicity and hepatotoxicity in vivo, showed higher level of drug in vital organs and revealed pronounced efficacy in elimination of the fungal burden in experimental animals infected with Candida albicans compared with those treated with free NYS. Niosomal encapsulation thus provided means for parenteral administration of NYS, reducing its toxicity and making it a more active antifungal agent.

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