Number of Affected Nails Is the Primary Determinant of Efinaconazole 10% Solution Usage for Onychomycosis

Good adherence to treatment is necessary for the successful treatment of onychomycosis and requires that an appropriate amount of medication be prescribed. Most prescriptions for efinaconazole 10% solution, a topical azole antifungal, are for 4 mL per month but there are no data on patient factors or disease characteristics that impact how much medication is needed. Data from two phase 3 studies of efinaconazole 10% solution for the treatment of toenail onychomycosis were pooled and analyzed to determine monthly medication usage based on the number of affected toenails, percent involvement of the target toenail, body mass index (BMI), and sex. Participants with two or more affected nails required, on average, >4 mL of efinaconazole per month, with increasing amounts needed based on the number of nails with onychomycosis (mean: 4.39 mL for 2 nails; 6.36 mL for 6 nails). In contrast, usage was not greatly impacted by target toenail involvement, BMI, or sex. Together, these data indicate that the number of affected nails should be the major consideration when determining the monthly efinaconazole quantity to prescribe. J Drugs Dermatol. 2024;23(2):110-112.    doi:10.36849/JDD.7676.