Overview of topical therapy for common superficial fungal infections and the role of new topical agents

Until recently the treatment options for superficial fungal infections have been limited mainly to the use of fungistatic drugs of the imidazole class, discovered in the 1960s. The recent development of allylamine and benzylamine compounds provides antifungal agents with fungicidal mechanisms of action. Both imidazole and allylamine/benzylamine drugs interfere with the production of ergosterol, an essential component of the fungal cell membrane; however, the newer drugs act at an earlier stage of the metabolic pathway than the azoles and cause an accumulation of squalene in the fungal cell, which leads to cell death. In vitro test results show that allylamine/benzylamine minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) are lower than the MICs and MFCs of azoles tested by the same methods. In studies using animal models of dermatophytosis, results have shown the efficacy of the allylamine/benzylamine drugs to be superior to that of azole drugs. Clinical trials have also shown significant differences favoring allylaminelbenzylamine drugs over imidazoles in the treatment of dermatophytosis. The fungicidal drugs provide earlier evidence of efficacy, higher cure rates with shorter treatment periods, and lower relapse rates than imidazoles in direct-comparison studies. The allylamine/benzylamine drugs have also shown high cure rates in patients with candidiasis.