How effective is topical miconazole or amorolfine for mild to moderately severe onychomycosis in primary care: the Onycho Trial - a randomised double-blind placebo-controlled trial.

Objectives: To evaluate the efficacy of topical miconazole or amorolfine compared to placebo for mild to moderately severe onychomycosis.

Design: Randomised, double-blind, placebo-controlled trial, with computer-generated treatment allocation at a 1:1:1 ratio.

Setting: Primary care, recruitment from February 2020 to August 2022.

Participants: 193 patients with suspected mild to moderately severe onychomycosis were recruited via general practices and from the general public, 111 of whom met the study criteria. The mean age of participants was 51 (SD 13.1), 51% were female and onychomycosis was moderately severe (mean OSI 12.1 (SD 8.0)).

Interventions: Once-daily miconazole 20 mg/g or once-weekly amorolfine 5% nail lacquer solution was compared with placebo (denatonium benzoate solution).

Main Outcome Measures: Complete, clinical and mycological cure at 6 months. Secondary outcomes were clinical improvement, symptom burden, quality of life, adverse effects, compliance, patient-perceived improvement and treatment acceptability.

Results: Based on intention-to-treat analysis, none of the participants receiving miconazole or amorolfine reached complete cure compared with two in the placebo group (OR not estimable (n.e.), p=0.493 and OR n.e., p=0.240, respectively). There was no evidence of a significant difference between groups regarding clinical cure (OR n.e., p=0.493 and OR 0.47, 95% CI 0.04 to 5.45, p=0.615) while miconazole and amorolfine were less effective than placebo at reaching both mycological cure (OR 0.25, 95% CI 0.06 to 0.98, p=0.037 and OR 0.23, 95% CI 0.06 to 0.92, p=0.029, respectively) and clinical improvement (OR 0.26, 95% CI 0.08 to 0.91, p=0.028 and OR 0.25, 95% CI 0.07 to 0.85, p=0.021, respectively). There was no evidence of a significant difference in disease burden, quality of life, adverse reactions, compliance, patient-perceived improvement or treatment acceptability.

Conclusions: Topical miconazole and amorolfine were not effective in achieving a complete, clinical or mycological cure of mild to moderately severe onychomycosis, nor did they significantly alleviate the severity or symptom burden. These treatments should, therefore, not be advised as monotherapy to treat onychomycosis.

Trial Registration Number: WHO ICTRP NL8193.