What is the treatment for Trichophyton (T.) rubrum onychomycosis?

From the Guidelines

Trichophyton rubrum onychomycosis is best treated with terbinafine 250 mg daily for 12-16 weeks. This recommendation is based on the highest quality evidence available, which demonstrates that terbinafine has higher efficacy rates compared to itraconazole in treating dermatophyte onychomycosis, including T. rubrum infections 1. The British Association of Dermatologists' guidelines for the management of onychomycosis 2014 suggest that terbinafine should be considered as the first choice of treatment due to its higher efficacy and tolerability, unless there are contraindications 1.

Key Considerations

• Terbinafine is licensed at a dose of 250 mg per day for 6 weeks in fingernail and 12–16 weeks in toenail infection 1.
• Itraconazole is an alternative option, licensed at a dose of 200 mg per day for 12 weeks continuously, or alternatively as pulse therapy at a dose of 400 mg per day for 1 week per month 1.
• Terbinafine has broad and potent fungicidal effects against dermatophytes, particularly T. rubrum and T. mentagrophytes, but has lower fungistatic activity against Candida species than the azoles 1.
• Patients should be re-evaluated 3–6 months after treatment initiation and further treatment should be given if the disease persists 1.

Important Safety Information

• Terbinafine is generally well tolerated, but there have been rare reports of serious adverse reactions, including Stevens–Johnson syndrome and toxic epidermal necrolysis 1.
• Baseline liver function tests and a complete full blood count are recommended in patients with a history of heavy alcohol consumption, hepatitis or haematological abnormalities 1.
• Oral terbinafine has minimal drug–drug interactions, but the only potentially significant drug interaction is with drugs metabolized by the cytochrome P450 2D6 isoenzyme 1.

From the FDA Drug Label

Terbinafine has been shown to be active against most strains of the following microorganisms both in vitro and in clinical infections: Trichophyton mentagrophytes Trichophyton rubrum The efficacy of terbinafine tablets in the treatment of onychomycosis is illustrated by the response of patients with toenail and/or fingernail infections who participated in three US/Canadian placebo-controlled clinical trials Terbinafine tablets, USP are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium). The treatment for Trichophyton (T.) rubrum onychomycosis is terbinafine (PO), with a dosage of:

• One 250 mg tablet once daily for 6 weeks for treatment of fingernail onychomycosis
• One 250 mg tablet once daily for 12 weeks for treatment of toenail onychomycosis 2, 2, 2

From the Research

Treatment Options for Trichophyton (T.) rubrum Onychomycosis

• Oral antifungal agents such as terbinafine and itraconazole are effective treatments for Trichophyton (T.) rubrum onychomycosis 3, 4, 5.
• Terbinafine has been shown to be more effective than griseofulvin, fluconazole, or itraconazole in treating this condition, with a cure rate of 70-80% and an excellent tolerability profile 5.
• Intermittent pulse-dosed terbinafine has also been found to be effective in treating Trichophyton rubrum nail bed onychomycosis, with a cure rate of 93% when administered for 7 consecutive days every 2-3 months 6.
• Topical antifungal agents such as tavaborole and efinaconazole have demonstrated good nail penetration and high negative culture rates in clinical trials, providing a safer alternative to oral therapy with fewer risks of drug-drug interactions 7.

Dosage and Administration

• The standard dosage of terbinafine for treating Trichophyton (T.) rubrum onychomycosis is 250 mg per day, administered for 12 weeks 3.
• Intermittent pulse-dosed terbinafine involves administering 250 mg per day for 7 consecutive days every 2-4 months 6.
• The optimal treatment duration and dosage may vary depending on the individual case and the severity of the infection.

Safety and Efficacy

• Oral antifungal agents such as terbinafine and itraconazole are generally well tolerated but may be limited by safety concerns and the potential for drug-drug interactions 7.
• Topical antifungal agents such as tavaborole and efinaconazole have demonstrated good safety and efficacy profiles, with fewer risks of drug-drug interactions 7.
• The choice of treatment should be based on the individual patient's characteristics, including their medical history, comorbidities, and the nature of the onychomycosis infection 7.