Terbinafine

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Terbinafine
Systematic (IUPAC) name
N,6,6-trimethyl-N-(naphthalen-1-ylmethyl) hept-2-en-4-yn-1-amine
Identifiers
CAS number	91161-71-6
ATC code	D01AE15 D01 BA02
PubChem	5402
DrugBank	APRD00508
Chemical data
Formula	C₂₁H₂₅N
Mol. mass	291.43 g/mol
Pharmacokinetic data
Bioavailability	Readily absorbed
Protein binding	>99%
Metabolism	Hepatic
Half life	36 hours
Excretion	?
Therapeutic considerations
Pregnancy cat.	B
Legal status
Routes	Oral topical

Terbinafine hydrochloride (Lamisil® in UK & US) is a synthetic allylamine antifungal. It is highly lipophilic in nature and tends to accumulate in skin, nails, and fatty tissues.

[edit] Pharmacology

Terbinafine hydrochloride is a white fine crystalline powder that is freely soluble in methanol and methylene chloride, soluble in ethanol, and slightly soluble in water.

Like other allylamines, terbinafine inhibits ergosterol synthesis by inhibiting squalene epoxidase -- an enzyme that is part of the fungal cell wall synthesis pathway (NB: the fungal cell wall, not the cell membrane). In layman's terms, it inhibits fungal and bacterial cell wall growth, causing the contents of the cell to be unprotected and eventually die.

[edit] Indications

Terbinafine is mainly effective on the dermatophytes group of fungi.

As a 1% cream or powder it is used for superficial skin infections such as jock itch (Tinea cruris), athlete's foot (Tinea pedis) and Ringworm.

Oral 250mg tablets are often prescribed for the treatment of onychomycosis of the toenail or fingernail due to the dermatophyte Tinea unguium. 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. Alcohol consumption should also be avoided while taking terbinafine.

[edit] Specific US issues

Many health insurance companies consider these infections to be a cosmetic problem, and either do not cover the cost of the months-long course of Lamisil, which can run into the thousands of dollars, or recommend use of less expensive alternatives like fluconazole.

v • d • e Antifungals (D01 and J02)
Antibiotics	Griseofulvin, Hitachimycin, Natamycin, Nystatin
Topical Azoles	Clotrimazole, Econazole, Fluconazole, Ketoconazole, Miconazole, Oxiconazole, Sertaconazole, Sulconazole, Tioconazole
Other topicals	Ciclopirox, Ethylparaben, Flucytosine, Salicylic acid, Selenium sulfide, Terbinafine, Tolnaftate
For systemic use	Amphotericin B, Anidulafungin, Caspofungin, Griseofulvin, Itraconazole, Terbinafine, Voriconazole
Other	Posaconazole, Thiabendazole, Tea tree oil