Terbinafine

Terbinafine

Systematic (IUPAC) name
[(2E)-6,6-dimethylhept-2-en-4-yn-1-yl](methyl)(naphthalen-1-ylmethyl)amine
Identifiers
CAS number	91161-71-6 78628-80-5
ATC code	D01AE15 D01BA02
PubChem	5402
DrugBank	APRD00508
ChemSpider	1266005
Chemical data
Formula	C21H25N
Mol. mass	291.43 g/mol
SMILES	eMolecules & PubChem
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
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Terbinafine hydrochloride (Lamisil in Australia, Belgium, Brazil, Canada, Chile, France, Germany, Hungary, Iceland, Mexico, Romania, United Kingdom, and United States, also sold under the name Corbinal in Turkey) is a synthetic allylamine antifungal. It is highly lipophilic in nature and tends to accumulate in skin, nails, and fatty tissues. As a generic it is sold under the name Zabel in Australia. It is now also available as a generic in the United States, Belgium and Switzerland.

In India, Terbinafine hydrochloride is available in topical form under the brand name Sebifin (Ranbaxy Labs) and Zimig (GSK Pharma).

Pharmacology

Terbinafine hydrochloride is a white fine crystalline powder that is freely soluble in methanol and dichloromethane, 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 membrane synthesis pathway. Because terbinafine prevents conversion of squalene to lanosterol, ergosterol cannot be synthesized. This is thought to change cell membrane permeability, causing fungal cell lysis.

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 other types of ringworm (Tinea corporis).

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. Alternatives to oral administration have been studied. In 2009, results from a clinical study of a new formulation (terbinafine in Transfersomes, referred to as TDT-067) for topical treatment of onychomycosis were reported by Celtic Pharma.^[1]

It has been found that terbinafine hydrochloride may induce or exacerbate subacute cutaneous lupus erythematosus. Persons with lupus erythematosus should first discuss possible risks with their doctor before initiation of therapy.^[2]

FDA approval

The U.S. Food and Drug Administration has approved the first generic versions of prescription Lamisil (terbinafine hydrochloride) tablets. The remaining patent or exclusivity for Lamisil expired on June 30, 2007.

On September 28, 2007, the FDA stated that Lamisil (terbinafine hydrochloride, by Novartis AG) is a new treatment approved for use by children age 4 and up. The antifungal granules can be sprinkled on a child's food to treat ringworm of the scalp, Tinea capitis. ^[3]

References