| Indication | For the treatment of dermatophyte infections of the toenail or fingernail caused by susceptible fungi. Also for the treatment of tinea capitis (scalp ringworm) and tinea corporis (body ringworm) or tinea cruris (jock itch). |
| Pharmacodynamics | Terbinafine is an allylamine antifungal agent and acts by inhibiting squalene epoxidase, thus blocking the biosynthesis of ergosterol, an essential component of fungal cell membranes. In vitro, mammalian squalene monooxygenase (squalene 2,3-epoxidase) is only inhibited at higher (4000 fold) concentrations than is needed for inhibition of the dermatophyte enzyme. Depending on the concentration of the drug and the fungal species test in vitro, Terbinafine may be fungicidal. However, the clinical significance of in vitro data is unknown. |
| Mechanism of action | Terbinafine is hypothesized to act by inhibiting squalene monooxygenase, thus blocking the biosynthesis of ergosterol, an essential component of fungal cell membranes. This inhibition also results in an accumulation of squalene, which is a substrate catalyzed to 2,3-oxydo squalene by squalene monooxygenase. The resultant high concentration of squalene and decreased amount of ergosterol are both thought to contribute to terbinafine's antifungal activity. |
| Absorption | Readily absorbed from gastrointestinal tract. |
| Volume of distribution | Not Available |
| Protein binding | >99% |
| Metabolism | Hepatic |
| Route of elimination | Prior to excretion, terbinafine is extensively metabolized. |
| Half life | 36 hours |
| Clearance | Not Available |
| Toxicity | Not Available |