Efinaconazole

Efinaconazole is a triazole antifungal agent used as a topical treatment for onychomycosis, the fungal infection of nails. It inhibits the fungal cytochrome P450 enzyme 14-α-demethylase (CYP51), blocking the conversion of lanosterol to ergosterol and thereby disrupting fungal cell membrane synthesis.

Indications and overview: It is approved for the treatment of toenail and fingernail onychomycosis caused by dermatophytes and certain yeasts. It is not indicated for superficial skin infections or nail dystrophy due to non-fungal causes. Efinaconazole’s efficacy is enhanced when nails are appropriately prepared, including cleaning and debridement of thickened nails.

Administration: The medication is a topical 10% solution applied once daily to the affected nail(s) and surrounding skin for about 48 weeks. Nails should be prepared prior to application as directed. Discontinue use if hypersensitivity or severe irritation occurs.

Pharmacology and interactions: Systemic exposure after topical application is low, reducing the potential for systemic adverse effects and drug interactions. Metabolism is primarily hepatic with minimal systemic activity, and due to low systemic absorption, interactions with other drugs are unlikely but should be considered in patients taking multiple azole antifungals.

Adverse effects: Common local reactions include application-site dermatitis, pruritus, and irritation at the application site. Rare systemic adverse effects have been reported; monitor for signs of hypersensitivity.

History and status: Efinaconazole was approved by the U.S. FDA in 2014 for onychomycosis and is available in multiple countries as a topical antifungal therapy.