What is terbinafine, and how does it work (mechanism of action)?
Terbinafine is an antifungal agent that is
taken by mouth or applied to the skin. Terbinafine acts by interfering with the
ability of fungi to make chemicals called sterols that are an important part of
the membrane that surrounds fungal cells and holds them together. This weakens
the cell membrane. Oral terbinafine is more effective for treating fungal nail
infections than griseofulvin (Fulvicin; Gris-Peg) and itraconazole (Sporanox),
two other antifungal agents used for treating fungal nail infections. Topical
terbinafine was approved by the FDA in 1993. Terbinafine oral tablets were
approved in 1996.
What brand names are available for terbinafine?
Lamisil, Lamisil AT
Is terbinafine available as a generic drug?
Yes
Do I need a prescription for terbinafine?
Yes (Tablets), OTC (Topical preparations)
What are the side effects of terbinafine?
The most common side effects of terbinafine are:
Oral terbinafine can cause liver failure sometimes leading to liver transplantation or death.
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What is the dosage for terbinafine?
- Tablets: The usual dose is 250 mg once daily for 6 weeks for
treatment of the fingernails, and 12 weeks for treatment of toenails. Optimal
results will not be seen for several months after treatment because it takes
time for new healthy nails to grow. Terbinafine may be taken with or without
food. - Cream, gel, spray, solution: Apply to affected area (s) once (jock itch,
ringworm) or twice daily (athletes foot) for about for 1 week.
Which drugs or supplements interact with terbinafine?
Rifampin reduces oral terbinafine blood
concentrations, potentially reducing the efficacy of terbinafine. Cimetidine (Tagamet)
may increase oral terbinafine blood levels, potentially increasing side effects
of terbinafine. Fluconazole (Diflucan) increases the blood levels of oral
terbinafine by 52%-69%. Potentially leading to increased side effects.
Is terbinafine safe to take if I’m pregnant or breastfeeding?
There are no adequate studies in
pregnant women. Since nail
fungus treatment can be delayed until after pregnancy there is no reason to use
oral terbinafine during pregnancy.
Breastfeeding mothers should not use oral terbinafine because terbinafine passes into breast milk.
What else should I know about terbinafine?
What preparations of terbinafine are available?
Tablets: 250 mg. Oral Granule: 125 and 187.5 mg. Cream,
Gel, solution, or spray: 1%.
How should I keep terbinafine stored?
All formulations should be stored at room temperature, 15 C – 30 C (59 F – 86 F).