In vitro and in vivo studies with flutrimazole, a new imidazole derivative with antifungal activity.

1-[(2-Fluorophenyl)(4-fluorophenyl)phenylmethyl]-1H-imidazole (flutrimazole, UR-4056, CAS 119006-77-8) is a new topical imidazole antifungal agent which displays potent broad-spectrum in vitro activity against dermatophytes, filamentous fungi and yeasts, saprophytic and pathogenic to animals and humans (MIC = 0.025-5.0 micrograms/ml). In most of these studies the activity of flutrimazole was comparable to that of clotrimazole and markedly higher than that of bifonazole (MIC differences of greater than or equal to 1 order of magnitude). Tested against Scopulariopsis brevicaulis (8 strains), both flutrimazole and clotrimazole exhibited fungistatic and fungicidal activity, and clotrimazole appeared something less active (MIC = 0.3-2.5 micrograms/ml) than flutrimazole (MIC = 0.15-0.6 micrograms/ml). In animal experiments, topical application of 1% and 2% flutrimazole, as a cream or solution, was highly effective in models of rat vaginal candidiasis and guinea-pig trichophytosis, giving a rate of cured or cured plus markedly improved animals higher than 80%. Flutrimazole shares the mode of action of other imidazole or triazole-containing antifungals, i.e. inhibition of fungal lanosterol 14 alpha-demethylase, as it strongly inhibits ergosterol biosynthesis in a cell-free homogenate of Candida albicans, with an IC50 value of 0.071 mumol/l.