Terbinafine

Indications

Terbinafine is used for: Tinea pedis, Tinea cruris, Tinea corporis, Dermatophytosis, Nail infections

Adult Dose

Oral Onychomycosis Adult: 250 mg once daily for 6 weeks (fingernail) or 12 weeks (toenail) Tinea Pedis, Tinea Corporis, Tinea Cruris Adult: 250 mg/day PO in single dose or divided q12hr 2-4 wk in tinea cruris, tinea corporis 2-6 wk for tinea pedis Hepatic impairment: Use not recommended in chronic or active liver disease

Child Dose

Tinea Capitis >4 years (<25 kg): 125 mg/day PO for 6 weeks >4 years (25-35 kg): 187.5 mg/day PO for 6 weeks >4 years (>35 kg): 250 mg/day PO for 6 weeks

Renal Dose

Renal impairment: Use not recommended if CrCl <50 mL/min

Administration

May be taken with or without food.

Contra Indications

Hypersensitivity, active or chronic liver disease, lactation.

Precautions

Preexisting liver or renal impairment, pregnancy. Perform liver function tests prior to oral therapy. Lactation: Drug excreted in breast milk; do not use

Pregnancy-Lactation

Pregnancy Available data from postmarketing cases in pregnant women are insufficient to evaluate drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes Animal data In animal reproduction studies, the drug did not cause malformations or any harm to fetus when administered to pregnant rabbits and rats during period of organogenesis at oral doses up to 12 and 23 times the maximum recommended human dose (MRHD) of 250 mg/day, respectively Because treatment of onychomycosis can be postponed until after pregnancy is completed, it is recommended that oral terbinafine not be initiated during pregnancy Lactation After oral administration, terbinafine is present in human milk; however, there are no data on effects on breastfed child or on milk production; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy; tablets and any potential adverse effects on breastfed child from therapy or from underlying maternal condition

Interactions

Possible increase in levels in drugs metabolised by CYP450 2D6. Decreased terbinafine concentration with rifampicin; increased terbinafine concentration with cimetidine.

Adverse Effects

Side effects of Terbinafine : >10% Headache (13%) 1-10% Rash (6%), Pruritus (3%), Nausea (3%), Diarrhea (6%), Dyspepsia (4%), Abdominal pain (2%), Taste disturbance (3%), Elevated liver function test results (3%), Visual disturbance (1%) Potentially Fatal: Liver failure, Stevens-Johnson syndrome, neutropaenia.

Mechanism of Action

Terbinafine causes fungal cell death by inhibiting squalene epoxidase, the main enzyme in sterol biosynthesis, resulting in ergosterol deficiency within fungal cell walls. It has fungicidal activity against dermatophytes and some yeast.