Investigational drugs for onychomycosis.

INTRODUCTION: Onychomycosis is the fungal infection of the nail plate by dermatophytes, yeasts and nondermatophyte molds. The treatment of onychomycosis poses many challenges due to low initial cure rates and a high rate of relapse and recurrence. Oral therapy is limited by adverse events and drug-drug interactions, whereas topical therapy has limited penetrance through the nail plate. AREAS COVERED: New and reformulated drugs are in development for the treatment of onychomycosis. Experimental molecules include both oral and topical azole molecules, topical reformulations of terbinafine, the benzoxaboroles tavaborole and AN2718, the aganocide NVC-422 and the photosensitizer Sylsens B. These drugs are in varying stages of development so results from in vitro studies to Phase III clinical trials are discussed to present a complete picture of the current development pipeline for onychomycosis. EXPERT OPINION: The development of new molecules from familiar and novel classes for both oral and topical administration is encouraging. It is clear that there is currently more emphasis on the development of topical drugs than orals, due to their lower potential for adverse events and drug-drug interactions. The emergence of novel molecular targets is encouraging for the possibility of combination therapy and any future drug-resistant strains of fungi.