An evaluation of the in vitro activity of terbinafine

Terbinafine has previously been shown to be highly active against dermatoph ytes and many other filamentous fungi. However, its activity against yeasts is controversial, with earlier reports suggesting that it has low activity , while more recent studies demonstrated that terbinafine is effective agai nst yeasts. In this study, the in vitro activity of terbinafine was evaluat ed against a broad range of fungal isolates. We examined the susceptibility of 100 yeast strains (10 species including Candida albicans, non-C. albica ns, fluconazole-susceptible and -resistant candidal strains), and 184 strai ns of filamentous fungi and dermatophytes (29 species including Aspergillus , Fusarium, Sporothrix, Trichophyton rubrum, T. mentagrophytes, T. tonsuran s, Microsporum canis and Epidermophyton floccosum), using the NCCLS M27-A m icrodilution methodology for yeasts and a modified M38-P methodology for mo ulds. The endpoint for terbinafine was defined as 80% inhibition compared w ith the growth control well. The mean yeast and filamentous fungi minimum i nhibitory concentration values +/- SEM (in mu g ml(-1)) for terbinafine wer e: 6.60 +/- 0.73 and 1.04 +/- 0.28 respectively. In conclusion, our data su ggest that terbinafine, in addition to its potent activity against dermatop hytes, is considerably effective against a broad range of yeasts and filame ntous fungi in vitro. Therefore, investigations concerning its antifungal a ctivity in vivo against such organisms should be pursued.