Oral terbinafine is used for the treatment of dermatophyte infections of the toenail or fingernail (onychomycosis, tinea unguium) caused by susceptible fungi.
Efficacy of terbinafine has been established in uncontrolled and placebo- or comparative drug-controlled studies in patients with toenail or fingernail onychomycosis. In these studies, patients were assessed for mycologic cure (negative observation of fungus in lesion scrapings prepared with potassium hydroxide, and negative culture of lesion scrapings), effective treatment (mycologic cure and either no nail involvement or more than 5 mm of unaffected new nail growth), or mycologic and clinical (no nail involvement) cure. Terbinafine has been shown to be active against most strains of Trichophyton rubrum andT. mentagrophytes both in vitro and in clinical infections of the nail. Although terbinafine is active in vitro against most strains of Epidermophyton floccosum, Candida albicans, and Scopulariopsis brevicaulis, efficacy of the drug in the treatment of onychomycosis caused by these organisms remains to be established in controlled clinical studies.
In the toenail studies, 12 weeks of oral therapy with terbinafine 250 mg daily was more effective than placebo or itraconazole 200 mg daily, and 16 weeks of oral terbinafine therapy at this dosage was more effective than up to 52 weeks of oral griseofulvin 500 mg daily. In these studies, 70-88% of patients experienced mycologic cure, 59% experienced effective treatment, and 38-57% experienced mycologic and clinical cure when evaluated 36-48 weeks after completion of terbinafine treatment; the clinical relapse rate was about 15% in those evaluated at least 6 months after experiencing clinical cure and at least 1 year after completion of terbinafine treatment. In a study comparing 4 months of continuous (250 mg daily) or intermittent (500 mg daily for 1 week each month) oral terbinafine or intermittent (400 mg daily for 1 week each month) oral itraconazole, a trend favoring continuous terbinafine therapy was observed, but statistically significant differences in cure rates among the regimens were not observed. In a treatment duration-ranging study comparing 6-, 12-, and 24-weeks of terbinafine therapy in patients with toenail infections, mycologic cure rates were substantially greater for the 12- or 24-week regimens compared with the 6-week regimen, but the 24-week regimen was not substantially more effective than the 12-week regimen. However, some patients who do not respond to an initial 12-week course of terbinafine therapy may respond to a second course with the drug.
In the fingernail studies, 75% of patients experienced effective treatment, and 59-90% of patients experienced mycologic and clinical cure when evaluated 18-42 weeks after completion of treatment with oral terbinafine 250 mg daily for 6 weeks. Extending the course of terbinafine therapy to 12 weeks in patients with fingernail infections does not appear to improve response substantially. In a study in patients with fingernail onychomycosis who received oral terbinafine 250 mg daily for 2 or 4 weeks, 65% exhibited mycologic and clinical cure 6 months after completion of therapy; the cure rate in those who received only 2 weeks of therapy was 45%.
Terbinafine may be particularly useful in patients who cannot tolerate azole antifungals (e.g., itraconazole) or when there are concerns regarding possible drug interactions between azole antifungals and other drugs the patient is receiving. However, liver failure (sometimes leading to death or liver transplant) has occurred rarely in patients with or without preexisting liver disease who were receiving oral terbinafine for the treatment of onychomycosis.
(See Hepatotoxicity under Warnings/Precautions: Warnings, in Cautions.)The choice of antifungal therapy for the treatment of onychomycosis should be individualized taking into consideration the prolonged (several months) nature and cost of therapy, and the possibility of relapse.
Oral terbinafine is used for the treatment of tinea capitis (scalp ringworm) caused by susceptible dermatophytes (e.g., Trichophyton, Microsporum).
Tinea capitis requires treatment with an oral antifungal. Topical therapies (e.g., shampoos containing selenium sulfide, povidone iodine, or ketoconazole; topical antifungals) are sometimes used as adjuncts to oral antifungal treatment and may reduce fungal shedding and risk of transmission or reinfection.
Oral griseofulvin generally has been considered the antifungal of choice for the treatment of tinea capitis; alternatives include oral fluconazole, itraconazole, or terbinafine, especially when tinea capitis does not respond to griseofulvin or when there are compliance problems with the griseofulvin regimen.
Oral terbinafine appears to be as effective as oral griseofulvin for the treatment of tinea capitis caused by Trichophyton, and requires a shorter duration of treatment which may increase compliance. However, there is some evidence that griseofulvin may be more effective than terbinafine when tinea capitis is caused by M. canis.
Tinea Corporis or Tinea Cruris
Oral terbinafine has been used for the treatment of tinea corporis (body ringworm) or tinea cruris (jock itch).
Topical antifungals usually are effective for the treatment of uncomplicated tinea corporis. An oral antifungal (griseofulvin, fluconazole, itraconazole, terbinafine) may be necessary if tinea corporis is extensive, dermatophyte folliculitis is present, the infection does not respond to topical therapy, or the patient is immunocompromised because of coexisting disease or concomitant therapy.
For information on topical uses of terbinafine,