Detailed Drug Information:

DRUG CLASS AND MECHANISM: Terbinafine is an antifungal agentthat is taken by mouth or applied to the skin. Terbinafine acts byinterfering with the ability of fungi to make chemicals called sterolsthat are an important part of the membrane that surrounds fungal cells andholds them together. This weakens the cell membrane. Oral terbinafine ismore effective for treating fungal nail infections than griseofulvin(Fulvicin; Gris-Peg) and itraconazole (Sporanox), two other antifungalagents used for treating fungal nail infections. Topical terbinafine wasapproved by the FDA in 1993. Terbinafine oral tablets were approved in1996.

PREPARATIONS: Tablets containing 250mg. Cream containing 1%terbinafine, 15gm and 30gm size tubes.

STORAGE: The tablets and the cream should be kept at roomtemperature, 15-30°C (59-86°F).

PRESCRIBED FOR: Tablets: Fungal infections of the toe, orfingernail, caused by the fungus, tinea unguium.

Cream: Fungal infections of the skin including tinea pedis ("athlete's foot"), tinea corporis, and tinea cruris ("jock itch").

DOSING: Tablets: The usual dose is 250 mg once daily for 6weeks for treatment of the fingernails, and 12 weeks for treatment oftoenails. Alternatively, terbinafine may be given as two tablets (500 mg)once daily for 7 days during the first week of each month for 3 months fortoenail infections. For children under 20kg (44 pounds), a dose of 62.5mg/day and for children between 20 and 40kg (44 and 88 pounds) a dose of125 mg/day have been recommended. Terbinafine may be taken with or withoutfood.

Cream: The cream is rubbed gently into the affected area (s). The creamusually is applied twice daily for 1 to 4 weeks.

DRUG INTERACTIONS: Rifampin reduces terbinafine bloodconcentrations, potentially reducing the efficacy of terbinafine, andcimetidine (Tagamet) may increase terbinafine blood levels. The lattereffect would not be expected to lead to problems.

PREGNANCY: Studies in animals using large dosages of terbinafinehave not demonstrated toxic effects on the fetus; however, there have notbeen conclusive studies in humans. Since fungal infections of the skin andnails usually are not a serious problem, the manufacturer of terbinafinedoes not recommend therapy during pregnancy.

NURSING MOTHERS: There is no data on the use of terbinafine during breast-feeding. Nursing mothers should avoid using terbinafine on the breast or taking the drug orally.

SIDE EFFECTS: Terbinafine is a very safe medication. The need todiscontinue therapy because of side effects is quite rare. The mostfrequently reported side effects are diarrhea, and abdominal pain.Increases in liver enzymes, hives, itching and altered taste sensationalso have been observed.