Overview
11 DESCRIPTION Terbinafine tablets, USP contain the synthetic allylamine antifungal compound terbinafine hydrochloride USP. Chemically, terbinafine hydrochloride is (E)- N -(6,6-dimethyl-2-hepten-4-ynyl)- N -methyl-1-naphthalenemethanamine hydrochloride. The molecular formula C 21 H 26 ClN with a molecular weight of 327.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Terbinafine is an allylamine antifungal [see ] . 12.2 Pharmacodynamics The pharmacodynamics of terbinafine tablets is unknown. 12.3 Pharmacokinetics Following oral administration, terbinafine is well absorbed (greater than 70%) and the bioavailability of terbinafine tablets as a result of first-pass metabolism is approximately 40%. Peak plasma concentrations of 1 mcg/mL appear within 2 hours after a single 250 mg dose; the AUC is approximately 4.56 mcg•h/mL. An increase in the AUC of terbinafine of less than 20% is observed when terbinafine tablets are administered with food. In plasma, terbinafine is greater than 99% bound to plasma proteins and there are no specific binding sites.
Indications
- 1 INDICATIONS AND USAGE Terbinafine tablets are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium). Prior to initiating treatment, appropriate nail specimens for laboratory testing [potassium hydroxide (KOH) preparation, fungal culture, or nail biopsy] should be obtained to confirm the diagnosis of onychomycosis. Terbinafine tablets are an allylamine antifungal indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium).
Common Doses
- 250 mg
Dosage
2 DOSAGE AND ADMINISTRATION • Prior to administering, evaluate patients for evidence of chronic or active liver disease. • Fingernail onychomycosis: One tablet, once daily for 6 weeks. • Toenail onychomycosis: One tablet, once daily for 12 weeks. 2.1 Assessment Prior to Initiation Before administering terbinafine tablets, evaluate patients for evidence of chronic or active liver disease [see Contraindications (4) and ]. 2.2 Dosage Fingernail onychomycosis: One 250 mg tablet once daily for 6 weeks. Toenail onychomycosis: One 250 mg tablet once daily for 12 weeks.
Contraindications
- 4 CONTRAINDICATIONS Terbinafine tablets are contraindicated in patients with: • Chronic or active liver disease [see ] • History of allergic reaction to oral terbinafine because of the risk of anaphylaxis [see ] • Chronic or active liver disease. (4) • History of allergic reaction to oral terbinafine because of the risk of anaphylaxis. (4)
Side Effects
- 6 ADVERSE REACTIONS Common (greater than 2% of patients treated with terbinafine tablets) reported adverse events include headache, diarrhea, rash, dyspepsia, liver enzyme abnormalities, pruritus, taste disturbance, nausea, abdominal pain, and flatulence. To report SUSPECTED ADVERSE REACTIONS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates in the clinical trials of a drug cannot be directly compared to rates in the...
Interactions
- 7 DRUG INTERACTIONS Terbinafine is an inhibitor of CYP450 2D6 isozyme and has an effect on metabolism of desipramine. Drug interactions have also been noted with cimetidine, fluconazole, cyclosporine, rifampin, and caffeine. 7.1 Drug-Drug Interactions In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug classes: tricyclic antidepressants, selective serotonin reuptake inhibitors, beta-blockers, antiarrhythmics class 1C (e.g.