Activity of terbinafine against serious fungal pathogens

Although primarily indicated for dermatophyte infections, the allylamine terbinafine is active in vitro against a broad spectrum of filamentous and dimorphic fungi, in most cases with a primary fungicidal action. Using the standard NCCLS M27-A assay, recent studies confirmed the high activity of terbinafine against dematiaceous fungi and other medically important moulds such as Aspergillus and Penicillium marneffei. Terbinafine displayed a geometric mean MIC of 1.4 micrograms/ml against Candida albicans (n = 259) and has significant in vitro activity against other species of Candida, Cryptococcus, Trichosporon and Blastoschizomyces. As an approach to treatment of refractory infections, interactions of terbinafine with azoles and other agents are being investigated. Terbinafine was synergistic with azoles (and in some cases amphotericin B) against Candida species, Trichosporon beigelii, Aspergillus species, Pseudallescheria boydii and Scopulariopsis brevicaulis, some of which were unresponsive to any drug used singly. Terbinafine combined with fluconazole showed potent synergy against fluconazole- and multidrug-resistant C. albicans isolates. In conclusion, recent in vitro data suggest that terbinafine, either alone or in combination with other antifungal drugs, has potential in the therapy of a range of more severe fungal infections, in addition to its current widespread use against dermatomycoses.