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

February 2024 | Volume 23 | Issue 2 | 110 | Copyright © February 2024


Published online January 20, 2024

Steven R. Feldman MD PhDa, Tracey C. Vlahovic DPMb, Warren S. Joseph DPMc, C. Ralph Daniel MDd, Boni Elewski MDe, Phoebe Rich MDf, Shari R. Lipner MD PhDg

aWake Forest School of Medicine, Winston-Salem, NC 
bTemple University School of Podiatric Medicine, Philadelphia, PA 
cArizona College of Podiatric Medicine, Midwestern University, Glendale, AZ 
dUniversity of Mississippi Medical Center, Jackson, MS 
eUniversity of Alabama at Birmingham School of Medicine, Birmingham, AL 
fOregon Health and Science University, Portland, OR 
gWeill Cornell Medicine, New York, NY

Abstract
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

INTRODUCTION

Topical onychomycosis therapies require extended treatment durations, and incomplete treatment can contribute to high relapse rates.1 Excellent treatment adherence is vital to optimize outcomes2 and requires that an adequate quantity of medication is prescribed. Efinaconazole 10% topical solution, an azole antifungal indicated to treat onychomycosis in patients aged 6 years and older, is available in 4 or 8 mL bottles. Perhaps because published data are lacking on factors impacting quantity of efinaconazole needed, 87% of efinaconazole prescriptions in 2022 were for one 4 mL bottle/month.3 Using clinical data, we analyzed the quantity of efinaconazole used by baseline patient demographics and clinical characteristics to estimate drug quantity to be prescribed for a given patient.

MATERIALS AND METHODS

In two identical, double-blind, phase 3 studies (NCT01008033; NCT01007708), adult participants (18 to 70 years; N=1655) with mild-to-moderate distal lateral subungual onychomycosis affecting 20% to 50% of 1 or more great (target) toenails were randomized 3:1 to treatment with efinaconazole 10% solution or vehicle, self-applied once daily for 48 weeks.4 Studies were conducted according to international scientific/ethical standards and all participants and/or legal guardians provided informed consent. Bottles of study product (10 mL) were weighed upon dispensation at each study visit (every 4 weeks) and upon return at the following visit. Monthly medication use was calculated (mean daily use [g/day] x 30 days/month x density of efinaconazole 10% solution [mL/g]) and analyzed post hoc based on number of affected toenails, percent involvement of the target toenail, body mass index (BMI), and sex.

RESULTS

Efinaconazole-treated participants in both studies (n=656 and 580) had on average 3.7 to 3.8 affected toenails.4 Among those with usage data (n=1067), over 55% had 4 or more affected toenails (Figure 1). For the 90% of participants with 2 to 6 affected nails, average medication use ranged from 4.39 to 6.36 mL/month, corresponding to 1.10 to 1.59 4 mL bottles/month; only the 10% of participants with one affected toenail used <4 mL of efinaconazole monthly. Additional subgroup analyses revealed no meaningful differences in efinaconazole usage based on target toenail involvement, BMI, or sex; average medication use was 4.69 to 5.29 mL/month, corresponding to
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