An Emulsion Formulation of Amphotericin B Improves the Therapeutic Index When Treating Systemic Murine Candidiasis

Abstract

Incorporating amphotericin B into liposomes was reported to decrease amphotericin B toxicity without a concomitant loss of antifungal efficacy. We formulated an alternative emulsion-based delivery system for amphotericin B and compared it with Fungizone. The maximal tolerated dose (MTD) in mice was 1 mg of Fungizone/kg; however, the MTD was greater than 9 mg of the Intralipid emulsion formulation/kg. The emulsion formulation and Fungizone were equipotent for treating systemic candidiasis in mice. Amphotericin B nephrotoxicity, as manifested by polyuria that was resistant to antidiuretic hormone, was markedly diminished when amphotericin B was administered as an emulsion to rats. Loss of potassium from human red blood cells was also reduced by formulating this agent within emulsions. The emulsion formulation extended the survival time of mice that had established Candida albicans infections, when compared with the Fungizone treatment. The efficacy and reduced toxicity of the amphotericin B emulsion are findings suggesting that the emulsion formulation is preferable to Fungizone.