Terbinafine is an antifungal taken by mouth or as a cream that clears skin and nail fungi. Oral nail treatment is long (weeks to months), but has high cure rates.
Also known as: Lamisil
Terbinafine may increase imipramine levels through CYP2D6 inhibition, intensifying anticholinergic and cardiac effects.
Terbinafine inhibits CYP2D6; imipramine is a substrate of this pathway.
Anticholinergic symptoms; ECG if treatment is prolonged.
Palpitations, urinary retention, confusion.
Watch for anticholinergic toxicity (dry mouth, urinary retention, constipation) and ECG changes; adjust the dose if needed.
DailyMed — Terbinafine HCl (Lamisil, RLD) and Imipramine HCl labels — note: setid 67e634b1 validates an otic combination label used only to confirm the CYP2D6 pathway; the TCA interaction citation follows EMC-UK (Terbinafine SmPC, Drug Interactions, CYP2D6): https://www.medicines.org.uk/emc/product/3347
Taking terbinafine with food slightly increases absorption and reduces gastric discomfort.
Take with a meal, always at the same time (site monograph).
EMC-UK — Terbinafine SmPC 4.2 (with or without food; with food improves tolerability).
Oral terbinafine causes idiosyncratic hepatotoxicity — contraindicated in chronic active liver disease.
Assess baseline transaminases in prolonged courses; discontinue if ALT > 2–3× ULN.
Site monograph (terbinafine — discontinue if ALT raised); EMC-UK terbinafine SmPC 4.3/4.4.
Renal clearance is reduced — adjust dose if CrCl < 50 ml/min.
Reduce dose in moderate/severe renal impairment.
EMC-UK — terbinafine SmPC 4.2 (CrCl < 50 ml/min).
No entry in the Prontuário Annex 1. Terbinafine is not teratogenic in animals, but human data are limited; labels (EMC/Lamisil) recommend avoiding in pregnancy unless clearly necessary (onychomycosis is not an emergency — treat after delivery).
Avoid; defer treatment of non-urgent mycoses until after delivery.
Terbinafine is excreted into milk (elevated levels in animals); EMC recommends avoiding breastfeeding during treatment.
EMC-UK (MHRA) — Terbinafine SmPC (Lamisil): https://www.medicines.org.uk/emc/product/2647/smpc (section 4.6). Prontuário Terapêutico INFARMED — 7.1.2 (Antifungals).
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
First-choice oral/topical allylamine fungicide for dermatophyte onychomycoses; the prolonged skin/nail depot allows finite treatments with high cure rates.
Selective inhibition of fungal squalene epoxidase (human isoform unaffected at therapeutic doses): intracellular squalene accumulation (membrane-toxic) and blocked ergosterol synthesis — fungicidal for dermatophytes, fungistatic for Candida (spectrum exception).
Oral absorption > 70% (increases ~20% with food); peak 1–2 h; extensive protein binding and high lipophilia with keratin diffusion (nail reaches therapeutic concentrations within weeks and persists after stopping).
Extensive hepatic biotransformation (CYP2C9, CYP1A2, CYP3A4, CYP2C8) to inactive metabolites, renally (~70%) and faecally excreted; weak CYP2D6 inhibition (monitor desipramine/tolterodine). Potent CYP2C9 inhibitors (fluconazole) and inducers (rifampicin) alter exposure.
~22 h initial (α phase) but terminal elimination half-life of ~200–400 h due to slow redistribution from the skin/nail depot — no dose adjustment needed (stop by clinical cure, not serum level).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
