AMPHOTERICIN B TOPICAL MICROEMULSION: DEVELOPMENT, STABILITY, AND IN VITRO CYTOTOXICITY EVALUATION

Amphotericin B (AmB) has been considered one of the most important antifungal agents over the last 60 years due to its broad-spectrum activity. However, its clinical application is limited by low aqueous solubility and systemic toxicity, especially nephrotoxicity. Nanotechnology, particulary microemulsion (ME) systems, has emerged as a promising solution to not only overcome these limitations but also offer controlled and targeted drug release. The use of vegetable oils, such as passion fruit seed oil, adds therapeutic value to the formulations owing to their anti-inflammatory properties and fatty acid content. To ensure safe topical application, it’s essential to evaluate the formulation's safety profile in cellular models representative of the skin and immune system. The present study aimed to develop and characterize ME containing AmB, evaluating strategies to improve drug incorporation, formulation stability, and safety through in vitro cytotoxicity assays. To increase drug incorporation, cholesterol was added to the formulation, and to improve stability the pH shift technique was applied, with tests at three time points under alkaline pH. ME was characterized by its droplet size measurement by dynamic light scattering, electrical conductivity, and pH monitoring over 60 days. In addition, formulation safety was evaluated through in vitro cytotoxicity assays in HaCaT, HFF-1, and RAW 264.7 cell lines. Cholesterol addition increased drug solubility by 1.8-fold. Amphotericin sedimentation was observed after three weeks, a problem overcome by the pH shift technique, which promoted formulation stability without sedimentation over 60 days. During the analyzed period, the formulations exhibited an average droplet size of 40 nm and PDI below 0.3, indicating a nanometric and homogeneous system. The pH remained between 5 and 6, consistent with a topical formulation. Cytotoxicity assays in the cell lines are ongoing, and complete results will be presented at the event. It was produced stable ME of AmB suitable for topic use. The ongoing cytotoxicity evaluation will characterize the formulation's safety profile, an essential step toward its potential topical use.