Comparative therapeutic efficacy of a novel lyophilized amphotericin B lecithin-based oil-water microemulsion and deoxycholate-amphotericin B in immunocompetent and neutropenic mice infected with Candida albicans.

The in vivo efficacy of a new amphotericin B (AmB) oil-in-water lecithin-based microemulsion delivery system (M-AmB) compared to deoxycholate-AmB (D-AmB) was studied in an immunocompetent and neutropenic murine model of systemic candidiasis. D-AmB was administered at the maximum tolerated dose of 1 mg/kg whereas M-AmB was given at the doses of 1, 2 and 3 mg/kg; doses were well tolerated due to their reduced toxicity. Both formulations were administered 24, 48 and 72 h after infection in immunocompetent mice, and 2, 6 and 24 h after infection in neutropenic mice. Kaplan-Meier survival curves showed that the M-AmB treated group had a better survival time than infected mice without treatment used as a control group (P = 4.66 x 10(-6)), and the Mann-Whitney W statistical test indicated that it reduced the percentage of mortality and fungal load in the most representative organs. This new formulation is a designed competitor which has proved to present better results than D-AmB in an established infection not only in immunocompetent but in neutropenic mice as well.