API

Terbinafine (1% w/w)

Drug classification

Antifungal agent; allylamine subclass.

Dosage form

Topical cream containing 1% w/w terbinafine.

API strength per dosage

Dose

Apply a thin layer of Zimig 1% Cream once or twice daily to affected skin, usually for 1–2 weeks depending on the infection. For adults and children over 12 years. Safety and efficacy in children under 12 not established. Use with caution in hepatic impairment; no dose adjustment for renal impairment. Avoid contact with eyes.

Mechanism of action

Terbinafine inhibits the fungal enzyme squalene epoxidase, blocking ergosterol synthesis in the cell membrane. This leads to accumulation of squalene and disruption of membrane integrity, resulting in fungal cell death. It is fungicidal against dermatophytes and fungistatic or fungicidal against some yeasts and molds.

Indications

Fungal skin infections

Side effects

Application site reactions burning irritation itching and redness Skin peeling Headache Diarrhea Rash Indigestion Abnormal liver enzyme Itching Taste change Nausea Abdominal pain Flatulence

Pregnancy category

Safety of topical terbinafine in pregnancy is not established; use only if potential benefit justifies potential risk to the fetus. Consult healthcare provider.

Precautions

Avoid contact with eyes, mucous membranes, or broken skin, discontinue if irritation or allergic reaction occurs, use with caution in pregnancy and lactation, not for oral, ophthalmic, or intravaginal use, monitor for local adverse reactions, ensure full course completion, keep out of reach of children.

Contraindications

Hypersensitivity to terbinafine or any excipients, known allergy to allylamine antifungals, avoid application to broken or inflamed skin, not for ophthalmic, oral, or intravaginal use.