The mode of antifungal action of tolnaftate

The anti-dermatophyte agent tolnaftate was compared with the allylamine antifungal compounds naftifine and terbinafine. Tolnaftate was shown to inhibit sterol biosynthesis at the level of squalene epoxidation and squalene was shown to accumulate in dermatophytes grown in its presence. Biochemical studies in whole and broken cells supported this conclusion and showed that the compound was active against squalene epoxidation in broken C. albicans cells, but was much less potent against whole cells. These results suggested there was a barrier to penetration in these yeasts.