Terbinafine
From Wikipedia, the free encyclopedia
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Terbinafine
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| Systematic (IUPAC) name | |
| N,6,6-trimethyl-N-(naphthalen-1-ylmethyl) hept-2-en-4-yn-1-amine | |
| Identifiers | |
| CAS number | |
| ATC code | D01 D01BA02 |
| PubChem | |
| DrugBank | |
| 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.
| 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 |
