Terbinafine hydrochloride  a synthetic a'llylamine antifungal. It is highly lipophilic in nature and tends to accumulate in skin, nails, and fatty tissues.   Terbinafine·HCl a member of the a'llylamine class of antifungals, has been found to be a specific inhibitor of ergosterol synthesis via squalene epoxidase inhibition. Squalene epoxidase is an enzyme released by the dermatophyte fungi to break down Squalene, which interferes with cell membrane function and wall synthesis.   Additionally, Terbinafine has also been reported to suppress cell proliferation in vitro and in vivo through inhibition of DNA synthesis and apoptosis activation. It has also been noted that by pretreating of cells with a p21 specific antisense oligonucleotide the Terbinafine induced inhibition of cell growth can be reversed.
 

Function:

Terbinafine hydrochloride is a white fine crystalline powder that is freely soluble in  d'ichloromethane, soluble in ethanol, and slightly soluble in water. Like other a'llylamines, terbinafine inhibits ergosterol synthesis by inhibiting squalene epoxidase, an enzyme that is part of the fungal cell membrane synthesis pathway. Because terbinafine prevents conversion ofsqualene to lanosterol, ergosterol cannot be synthesized. This is thought to change cell membrane permeability, causing fungal cell lysis.

1. Terbinafine Hcl is mainly effective on the  dermatophyte group of fungi .
2. As a 1% cream or powder, it is used topically for superficial skin infections such as jock itch (tinea cruris), athlete's foot (tinea pedis), and other types of ringworm (tinea corporis). Terbinafine cream works in about half the time required by other antifungals.
3. Oral 250mg tablets are often prescribed for the treatment of onychomycosis, a fungal nail infection, typically by a dermatophyte or Candida species. Fungal nail infections are located deep under the nail in the cuticle to which topically applied treatments are unable to penetrate in sufficient amounts. The tablets may, rarely, cause hepatotoxicity, so patients are warned of this and may be monitored with liver function tests. Alternatives to oral administration have been studied. 
4. Terbinafine may induce or exacerbate subacute cutaneous lupus erythematosus. Persons with lupus erythematosus should first discuss possible risks with their doctor before initiation of therapy.