Methyl aminolevulinate photodynamic therapy for onychomycosis: a multicentre, randomized, controlled clinical trial

Background Onychomycosis is a common fungal nail infection that responds poorly to antifungals. Objective To investigate the efficacy and safety of methyl aminolevulinate (MAL) photodynamic therapy (PDT) in the treatment of onychomycosis. Methods A multicentre (3), randomized, placebo‐controlled clinical trial compared the effects of three sessions of urea (40%) plus conventional MAL‐PDT with urea (40%) plus placebo (red light) photodynamic therapy (pPDT) in onychomycosis patients. Efficacy, both clinical (onychomycosis severity index, OSI) and microbiological, was blindly evaluated after 36 weeks of follow‐up. Results Forty patients were analysed in the trial. Twenty‐two received MAL‐PDT and 18 pPDT. A complete response (OSI = 0) was observed for four patients (18.18%) in the MAL‐PDT group and one (5.56%) in the pPDT group (NTT 7.92, 95% CI: 2.98–9.69, P = 0.23). A decrease in OSI score of over 75% (OSI75) was achieved by 40.91% of the patients in the MAL‐PDT group and 16.67% in the pPDT group (P = 0.096). Microbiological cure was achieved by seven patients (31.82%) in the MAL‐PDT group and two (11.11%) in the pPDT group (P = 0.178). MAL‐PDT resulted in better rates of clinical response [OSI >75%: 53.85% vs. 18.75% (P =0.048)] and microbiological cure [41.56% vs. 7.14% (P = 0.037)] in non‐dystrophic vs. dystrophic onychomycosis patients. No significant side‐effects were reported. The limitations of the study were the reduced sample size and the unexpected efficacy of the control treatment, which was attributed to the 40% urea pre‐treatment. Conclusion This study did not show significant differences between urea 40% + MAL‐PDT and urea 40% + pPDT in the treatment of onychomycosis. However, some results suggest that this treatment may constitute an alternative for dermatophyte and non‐dermatophyte mould onychomycosis in patients not eligible for systemic treatment, particularly in the absence of total nail dystrophy.