From the Guidelines
Terbinafine should be considered as the first choice for treating dermatophyte onychomycosis due to its higher efficacy and tolerability compared to itraconazole. When treating onychomycosis, the dosage of terbinafine is typically 250 mg per day for 6 weeks in fingernail and 12–16 weeks in toenail infection 1. Key points to consider when prescribing terbinafine include:
- Re-evaluating patients 3–6 months after treatment initiation and providing further treatment if the disease persists 1
- Being aware of potential side effects such as headache, gastrointestinal disturbances, and skin reactions
- Informing patients to take oral terbinafine with food to minimize stomach upset and to complete the full prescribed course even if symptoms improve earlier
- Considering potential interactions and contraindications, particularly in patients with liver disease or those taking certain medications 1. Several large studies demonstrate higher efficacy rates for terbinafine in comparison with itraconazole, with one multicentre, randomized trial involving 508 subjects showing complete cure in 55% of patients receiving 16 weeks of continuous terbinafine 1. In terms of long-term effectiveness, a 5-year blinded prospective follow-up study found mycological cure without a second therapeutic intervention in 46% of terbinafine-treated patients, compared to 13% of itraconazole-treated patients 1.
From the FDA Drug Label
Terbinafine tablets are an allylamine antifungal indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium) Terbinafine is a prescription antifungal medicine used to treat fungal infections of the fingernails and toenails (onychomycosis). The main use of terbinafine is to treat fungal infections of the fingernails and toenails.
- Key points about terbinafine include: + It is an antifungal medicine. + It is used to treat onychomycosis, a fungal infection of the nails. + The treatment duration is usually 6 weeks for fingernail onychomycosis or 12 weeks for toenail onychomycosis. + Patients should be advised to report any symptoms of liver problems, taste disturbance, smell disturbance, depressive symptoms, or serious skin or allergic reactions to their physician. + Terbinafine may cause serious side effects, including liver problems, change in taste or loss of taste, change in smell or loss of smell, and depressive symptoms 2, 3, 4.
From the Research
Mechanism of Action
- Terbinafine inhibits the biosynthesis of ergosterol, a principal sterol in fungi, at the level of squalene epoxidase, resulting in a fungistatic effect and the toxic accumulation of intracellular squalene, leading to a fungicidal effect 5.
- The drug has demonstrated excellent fungicidal activity against dermatophytes and variable activity against yeasts and non-dermatophyte molds in vitro 5, 6.
Efficacy
- Terbinafine has been shown to be highly effective in the treatment of onychomycosis, with mycological cure rates of 76% +/- 3% in randomized controlled trials 7.
- The drug has been found to be more effective than itraconazole, fluconazole, and griseofulvin in the treatment of dermatophyte onychomycosis 5, 7, 6.
- Terbinafine has also been shown to be effective in the treatment of tinea pedis, tinea corporis/cruris, and tinea capitis 6, 8.
Safety and Tolerability
- Terbinafine has been found to be well tolerated, with a low potential for drug interactions 5, 7, 6.
- The most common adverse events associated with terbinafine are gastrointestinal complaints, which occur in approximately 10.5% of patients 5.
- The drug has been shown to be safe and effective in special populations, including children, the elderly, and immunocompromised patients 7, 9.