Terbinafine (Oral)

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Contents

[edit] BRAND NAMES

[edit] STRUCTURE

Terbinafine.jpg

[edit] MECHANISM OF ACTION

Terbinafine inhibits squalene epoxidase, this results in deceased synthesis of ergosterol and accumulation of toxic squalene (fungicidal effect). Ergosterol is an essential component of the fungal cell membrane. The inhibition of its synthesis results in accumulation of toxic 14α-methylated sterols and the production of a defective cell membrane with altered permeability and leakage of cellular contents.

[edit] INDICATIONS

  • Treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium)

[edit] DOSAGE

  • Fingernail onychomycosis: One 250 mg tablet, once daily for 6 weeks
  • Toenail onychomycosis: One 250 mg tablet, once daily for 12 weeks

[edit] DOSAGE FORMS AND STRENGTHS

Tablet, 250 mg

[edit] CONTRAINDICATIONS

  • Patients with a history of allergic reaction to oral terbinafine because of the risk of anaphylaxis

[edit] WARNINGS AND PRECAUTIONS

  • Liver failure, sometimes leading to liver transplant or death, has occurred with the use of oral terbinafine. Obtain pretreatment serum transaminases. Discontinue Terbinafine (Oral) if liver injury develops.
  • Taste disturbance, including taste loss, has been reported with the use of Terbinafine (Oral). Taste disturbance can be severe, may be prolonged, or may be permanent. Discontinue Terbinafine (Oral) if taste disturbance occurs.
  • Smell disturbance, including loss of smell, has been reported with the use of Terbinafine (Oral). Smell disturbance may be prolonged, or may be permanent. Discontinue Terbinafine (Oral) if smell disturbance occurs.
  • Depressive symptoms have been reported with terbinafine use. Prescribers should be alert to the development of depressive symptoms.
  • Severe neutropenia has been reported. If the neutrophil count is <1000 cells/mm3, Terbinafine (Oral) should be discontinued.
  • Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, exfoliative dermatitis, bullous dermatitis, and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome have been reported with oral terbinafine use. If signs or symptoms of drug reaction occur, treatment with Terbinafine (Oral) should be discontinued.

[edit] INTERACTIONS

Terbinafine is metabolized in liver but does not significantly inhibit or induce CYP450 (less interactions if compared to Azoles)[1]

[edit] PREGNANCY AND LACTATION

  • Pregnancy Category B (US). It is recommended that Terbinafine (Oral) not be initiated during pregnancy.
  • Nursing Mothers: After oral administration, terbinafine is present in breast milk of nursing mothers. The ratio of terbinafine in milk to plasma is 7:1. Treatment with Oral Terbinafine is not recommended in women who are nursing.

[edit] SIDE EFFECTS

Common (>2% of patients treated with Lamisil Tablets) reported adverse events include headache, diarrhea, rash, dyspepsia, liver enzyme abnormalities, pruritus, taste disturbance, nausea, abdominal pain, and flatulence

[edit] RELATED LINKS

[edit] BIBLIOGRAPHY

http://www.pharma.us.novartis.com/product/pi/pdf/Lamisil_tablets.pdf

[edit] REFERENCES

  1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1661633/
Antifungals
Ergosterol target : Cell membrane target Azoles (lanosterol 14 alpha-demethylase inhibitors) : Ergosterol inhibitors Imidazoles Topical: Bifonazole   Clotrimazole   Econazole   Fenticonazole   Ketoconazole   Isoconazole   Miconazole   Sertaconazole   Tioconazole
Triazoles Topical: Fluconazole   Terconazole
Systemic: Fluconazole   Itraconazole   Posaconazole   Voriconazole
Polyene antimycotics (ergosterol binding; they form pores in the membrane) Topical: Nystatin
Systemic: Amphotericin B
Allylamines (squalene epoxidase inhibitors) : Ergosterol inhibitors Topical: Amorolfine   Naftifine   Terbinafine
Systemic: Terbinafine
Echinocandins (β-glucan synthase inhibitors) : Cell wall target Anidulafungin   Caspofungin   Micafungin
Pyrimidine analogues / Thymidylate synthase inhibitors : Nucleic acid inhibitors Flucytosine
Mitotic inhibitors Griseofulvin
Others Ciclopirox