From the Guidelines
Oral terbinafine is the most effective treatment for nail fungus (onychomycosis), with higher efficacy rates compared to itraconazole, and should be considered as the first-line treatment. The standard treatment regimen is 250 mg once daily for 6 weeks for fingernail infections and 12 weeks for toenail infections, as recommended by the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1. This medication works by inhibiting the enzyme squalene epoxidase, which disrupts fungal cell membrane synthesis, ultimately killing the fungus. Terbinafine is particularly effective against dermatophytes, the most common cause of nail fungus.
Key Points to Consider
- Patients should take the medication with or without food and continue for the full prescribed duration even if improvement is seen earlier, as the nail must grow out completely to eliminate the infection.
- Common side effects include headache, gastrointestinal upset, and rash.
- Before starting treatment, liver function tests are typically recommended as rare but serious liver toxicity can occur, as noted in the guidelines 1.
- Terbinafine may interact with certain medications, so patients should inform their healthcare provider about all medications they're taking.
- Complete nail healing may take several months after finishing the medication as healthy nail grows in to replace the infected portion.
Treatment Efficacy
The efficacy of terbinafine has been demonstrated in several large studies, including a multicentre, randomized trial involving 508 subjects, which showed complete cure rates of 55% for terbinafine compared to 26% for pulsed itraconazole at follow-up at 72 weeks 1. A 5-year blinded prospective follow-up study also found that mycological cure without a second therapeutic intervention was higher in terbinafine-treated patients (46%) compared to itraconazole-treated patients (13%) 1.
Comparison with Other Treatments
In comparison to other treatments, terbinafine has been shown to be superior to itraconazole both in vitro and in vivo for dermatophyte onychomycosis, and should be considered first-line treatment, with itraconazole as the next best alternative 1. The British Association of Dermatologists' guidelines also recommend terbinafine as the first-line treatment for dermatophyte onychomycosis, due to its higher efficacy and tolerability compared to other treatments 1.
From the FDA Drug Label
The mean time to overall success was approximately 10 months for the first toenail study and 4 months for the fingernail study. In the first toenail study, for patients evaluated at least six months after achieving clinical cure and at least one year after completing terbinafine therapy, the clinical relapse rate was approximately 15% Patients should take one 250 mg tablet once daily for 6 weeks for treatment of fingernail onychomycosis or once daily for 12 weeks for treatment of toenail onychomycosis The optimal clinical effect is seen some months after mycological cure and cessation of treatment due to the time period required for outgrowth of healthy nail.
The effectiveness of oral terbinafine in treating nail fungus is supported by the drug label, which reports a mean time to overall success of approximately 10 months for toenail study and 4 months for fingernail study, with a clinical relapse rate of approximately 15%. The treatment regimen consists of taking one 250 mg tablet once daily for 6 weeks for fingernail onychomycosis or 12 weeks for toenail onychomycosis. The optimal clinical effect is seen after mycological cure and cessation of treatment, due to the time required for outgrowth of healthy nail 2.
From the Research
Effectiveness of Oral Terbinafine in Treating Nail Fungus
- Oral terbinafine has demonstrated excellent fungicidal activity against dermatophytes and variable activity against yeasts and non-dermatophyte molds in vitro 3.
- Randomized, double-blind trials have shown that oral terbinafine 250 mg/day for 12 or 16 weeks is more efficacious than itraconazole, fluconazole, and griseofulvin in dermatophyte onychomycosis of the toenails 3.
- The L.I.ON. study found that mycologic cure rates and complete cure rates were approximately twice as high after terbinafine treatment than after itraconazole 3.
- A randomized treatment duration-finding study of terbinafine in onychomycosis found that a treatment period of 12 weeks is sufficient for toenail onychomycosis 4.
- A multicenter trial of various treatment durations found that mycologic cure rates at week 72 were 72.1% in the 12-week treatment group, 72.5% in the 18-week group, and 77.0% in the 24-week group 5.
Treatment Duration and Regimen
- A study found that a quarterly terbinafine pulse regimen can be a possible alternative for treating onychomycosis caused by dermatophytes, with no statistical differences regarding effectiveness or side effects compared to conventional treatment 6.
- The preferred regimen for the treatment of dermatophyte onychomycosis is terbinafine 250 mg/day for 12 weeks 7.
- Pulse therapy with terbinafine, administered for 1 week with 3 weeks off treatment between successive pulses, may be an effective treatment option 7.
Safety and Tolerability
- Oral terbinafine has a better tolerability profile than griseofulvin and a comparable profile to that of itraconazole or fluconazole 3.
- Adverse events were experienced by 10.5% of terbinafine recipients, with gastrointestinal complaints being the most common 3.
- Terbinafine has a low potential for drug-drug interactions, unlike the azoles 3.