What are the topical treatments for distal subungual onychomycosis (DSUO), a type of fungal infection of the nail?

From the Guidelines

Topical treatments for saprophytic onychomycosis should include antifungal nail lacquers and solutions containing amorolfine 5%, which has been shown to be effective in around 50% of cases of distal fingernail and toenail onychomycosis 1. When treating saprophytic onychomycosis, it is essential to consider the causative organisms, which are often non-dermatophyte molds like Aspergillus, Fusarium, or Scopulariopsis that colonize already damaged nails. These organisms are often more resistant to standard treatments, making longer treatment courses necessary.

• Amorolfine 5% lacquer is applied to the affected nail once or twice weekly for 6–12 months, after removal of as much of the diseased areas of the nail as possible by gentle filing 1.
• Ciclopirox 8% lacquer is another option, applied once daily for up to 48 weeks, with removal using alcohol once weekly before reapplication 1.
• It is crucial to ensure complete coverage of the nail plate and surrounding skin, and to maintain dry, clean nails and avoid trauma to the nail plate to prevent recurrence after successful treatment.
• Over-the-counter options like tea tree oil or undecylenic acid preparations may provide some benefit as adjunctive therapy but are less effective as standalone treatments.
• The clinical improvement obtained with amorolfine and other topical antifungals may not be synonymous with mycological cure, which has invariably lower rates, often by 30% 1.

From the FDA Drug Label

Ciclopirox Topical Solution, 8%, (Nail Lacquer), as a component of a comprehensive management program, is indicated as topical treatment in immunocompetent patients with mild to moderate onychomycosis of fingernails and toenails without lunula involvement, due to Trichophyton rubrum The topical treatment for saprophytic onychomycosis is Ciclopirox Topical Solution, 8%, (Nail Lacquer), as part of a comprehensive management program, for immunocompetent patients with mild to moderate onychomycosis of fingernails and toenails without lunula involvement, due to Trichophyton rubrum 2.

• The treatment should be used under medical supervision.
• The comprehensive management program includes removal of the unattached, infected nails as frequently as monthly, by a health care professional.
• No studies have been conducted to determine whether ciclopirox might reduce the effectiveness of systemic antifungal agents for onychomycosis.

From the Research

Topical Treatments for Saprophytic Onychomycosis

• Topical treatments for onychomycosis include amorolfine 5% and ciclopirox 8% nail lacquers, which can be used alone or in combination with oral antifungal agents 3.
• Ciclopirox nail lacquer 8% has been shown to be effective in the treatment of mild to moderate onychomycosis, with mycologic cure rates ranging from 29% to 85.7% in different studies 4.
• A study comparing ciclopirox 8% HPCH nail lacquer with amorolfine 5% found that ciclopirox was statistically superior in achieving treatment success and complete cure 5.
• Newer topical antifungal agents, such as efinaconazole 10% solution and tavaborole 5% solution, have been developed and have shown promising results in clinical trials, with mycologic cure rates superior to those achieved with ciclopirox 8% nail lacquer 6.
• Combining oral and topical antifungal drugs, such as terbinafine and amorolfine or ciclopirox, may enhance treatment success rates due to additive or synergistic modes of action 7.

Mechanism of Action and Efficacy

• Amorolfine and ciclopirox have different modes of action, but both exhibit broad antifungal activity 3.
• Ciclopirox has a novel mechanism of action and offers an innovative approach to the treatment of onychomycosis 4.
• The efficacy of topical antifungal therapy for onychomycosis can be improved by combining it with oral antifungal agents or using newer topical agents with improved penetration and efficacy 6.

Safety and Tolerability

• Ciclopirox nail lacquer is considered extremely safe, with most treatment-emergent adverse effects being transient and localized to the site of action 4.
• Newer topical antifungal agents, such as efinaconazole 10% solution and tavaborole 5% solution, have been shown to be well-tolerated and easy to use 6.