LAMISIL 250/MG TAB 14/TAB

Indications

Approved Uses

Onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium)

Dosage & Administration

Dosing by Condition

Onychomycosis (fingernails): 250 mg once daily for 6 weeks. Onychomycosis (toenails): 250 mg once daily for 12 weeks.

Initial Dose

250 mg once daily

Maintenance Dose

250 mg once daily

Maximum Dose

250mg once daily.

Children's Dosage

Not approved for onychomycosis in children; for tinea capitis (patients 4 years and older): <25 kg: 125 mg once daily; 25-35 kg: 187.5 mg once daily; >35 kg: 250 mg once daily for 6 weeks (oral granules).

Dose Adjustment Notes

Contraindicated/not recommended in chronic or active liver disease; in renal impairment (CrCl <50 mL/min) use is generally not recommended-if used, many references suggest reducing the dose by ~50% with close monitoring.

How to Take

Swallow the tablet whole with water; may be taken with or without food; take once daily at the same time each day.

Side Effects

Common Side Effects

Headache; gastrointestinal effects (diarrhea, dyspepsia, nausea, abdominal pain/flatulence); rash/pruritus/urticaria; taste disturbance; and possible elevations in liver enzymes.

Safety & Warnings

Contraindications

Hypersensitivity to terbinafine (or excipients) and chronic or active liver disease; severe renal impairment is generally a 'not recommended/avoid' situation rather than a strict contraindication.

Warnings & Precautions

Baseline liver function tests before starting; stop immediately with symptoms/signs of liver injury; counsel on and stop for progressive rash/SJS-TEN symptoms; caution in psoriasis or lupus; consider CBC if prolonged therapy or if infection symptoms occur; stop and evaluate if significant taste/smell disturbance occurs.

Age Restriction

Oral terbinafine tablets are generally not recommended/approved for children; use in pediatrics (e.g., tinea capitis) is typically off‑label and product labeling commonly limits tablet use to adults (onychomycosis not indicated in <18 years).

Drug Interactions

Drug Interactions

Key interactions: rifampicin (↓ terbinafine levels), cimetidine (↑ terbinafine levels), strong CYP inhibitors/inducers affecting terbinafine; terbinafine inhibits CYP2D6 (↑ TCAs, SSRIs, some beta‑blockers e.g., metoprolol, antiarrhythmics e.g., flecainide/propafenone; may reduce codeine/tramadol activation); cyclosporine levels may decrease; warfarin effect may change-monitor INR.

Interaction Severity

MAJOR/clinically significant: rifampicin (markedly decreases terbinafine levels/efficacy) and strong CYP inhibitors like cimetidine (increase terbinafine exposure); IMPORTANT due to CYP2D6 inhibition: increased effects/toxicity of CYP2D6 substrates (e.g., TCAs, SSRIs, metoprolol, flecainide/propafenone) and reduced activation of codeine/tramadol; warfarin-monitor INR.

Food Interaction

No clinically significant food restriction; may be taken with or without food.

Special Populations

Pregnancy

Not assigned (Risk Summary: Based on animal data, may cause bone malformations; available data from cases insufficient to inform risk)

Breastfeeding

Not recommended

Children

Not approved for onychomycosis in children; for tinea capitis (patients 4 years and older): <25 kg: 125 mg once daily; 25-35 kg: 187.5 mg once daily; >35 kg: 250 mg once daily for 6 weeks (oral granules).

Elderly

Standard adult dosing; however, monitor renal and hepatic function before and during treatment as age-related decline may affect drug clearance

Liver Impairment

Contraindicated in chronic or active liver disease; no dose adjustment is recommended for mild impairment because oral terbinafine should generally be avoided if hepatic disease is present-baseline LFTs are required and stop if hepatotoxicity signs occur.

Storage & Patient Advice

Stopping the Medicine

Do not stop early without prescriber advice; complete the prescribed course unless adverse effects occur (then stop and seek medical care).

Overdose

Symptoms may include headache, nausea, epigastric/abdominal pain, dizziness; management is supportive with consideration of activated charcoal (and gastric decontamination if very recent) and urgent medical evaluation; no specific antidote.

Patient Counseling

Complete the full prescribed course; report symptoms of liver injury immediately (fatigue, anorexia, persistent nausea/vomiting, RUQ pain, dark urine, pale stools, jaundice) and stop/seek care if they occur; report severe rash, fever/sore throat, or taste/smell disturbance; review all medicines for interactions (notably antidepressants/beta-blockers/antiarrhythmics, rifampicin, warfarin); limit alcohol and attend any scheduled lab monitoring.

Monitoring Requirements

Baseline liver function tests (ALT/AST) before starting; repeat if symptoms of hepatotoxicity occur and commonly at ~4-6 weeks for longer courses; consider CBC if prolonged therapy or if infection/hematologic symptoms develop; assess renal function when clinically indicated.

Pharmacology

Mechanism of Action

Inhibits fungal squalene epoxidase → decreased ergosterol synthesis and intracellular squalene accumulation → fungicidal activity against dermatophytes.

Onset of Action

Antifungal activity begins within days; symptom improvement for skin infections often within 1-2 weeks, while nail infection improvement is delayed and becomes evident over weeks to months as the nail grows.

Duration of Effect

Drug persists in keratinized tissues (skin/nails) for weeks to months after stopping; clinical clearing of nails continues as the nail grows out.

Half-Life

Effective plasma half-life ~36 hours; terminal half-life ~200-400 hours (reflecting slow release from skin/adipose)

Bioavailability

Approximately 40% (oral bioavailability; reduced by first-pass metabolism)

Metabolism

Extensive hepatic metabolism via multiple CYP isoenzymes (notably CYP1A2, CYP2C9, CYP2C19, CYP3A4, and CYP2D6) to inactive metabolites

Protein Binding

>99%

Product Information

Available Dosage Forms

Tablet, 250 mg

Composition per Dose

Each tablet: 250 mg terbinafine (as hydrochloride 281.25 mg)

Generic Availability

Yes

Application

Oral

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