LAMICTAL 50/MG TAB 30/TAB

Indications

Approved Uses

Epilepsy (adjunctive and monotherapy for partial seizures, generalized tonic-clonic seizures, seizures associated with Lennox-Gastaut syndrome), maintenance treatment of bipolar I disorder to delay mood episodes

Off-Label Uses

Common off-label uses include acute bipolar depression (treatment), augmentation in treatment-resistant unipolar depression, certain neuropathic pain syndromes (limited evidence), and other psychiatric indications with variable/limited evidence; trigeminal neuralgia and borderline personality disorder have limited/inconsistent supporting data.

Dosage & Administration

Dosing by Condition

Use product-specific labeling; typical IR titration (adults): (A) With valproate: 25 mg every other day x2 weeks, then 25 mg daily x2 weeks, then increase by 25-50 mg/day every 1-2 weeks; usual maintenance 100-200 mg/day. (B) With enzyme inducers without valproate: 50 mg daily x2 weeks, then 100 mg/day in 2 divided doses x2 weeks, then increase by 100 mg/day every 1-2 weeks; usual maintenance 300-500 mg/day (range often 200-400 mg/day depending on regimen). (C) Bipolar I maintenance (no valproate/inducers): 25 mg daily x2 weeks, 50 mg daily x2 weeks, 100 mg daily x1 week, then 200 mg daily maintenance.

Initial Dose

25 mg once daily for 2 weeks (monotherapy without enzyme inducers or valproate); 25 mg every other day for 2 weeks (with valproate); 50 mg once daily for 2 weeks (with enzyme-inducing AEDs without valproate

Maintenance Dose

200-400mg per day for bipolar disorder; 300-500mg per day for epilepsy (monotherapy or with enzyme inducers).

Maximum Dose

Maximum dose depends on indication and concomitant drugs: Epilepsy-up to 500 mg/day with enzyme-inducing AEDs (without valproate); Bipolar I maintenance-200 mg/day (100 mg/day with valproate; up to 400 mg/day with enzyme inducers).

Children's Dosage

Epilepsy (2-12 years, adjunct with valproate): 0.15mg/kg/day for 2 weeks, then 0.3mg/kg/day for 2 weeks, maintenance 1-5mg/kg/day. Epilepsy (2-12 years, with enzyme inducers without valproate): 0.6mg/kg/day for 2 weeks, then 1.2mg/kg/day for 2 weeks, maintenance 5-15mg/kg/day. Not approved for bipolar disorder in patients under 18 years

Dose Adjustment Notes

Titrate slowly to reduce serious rash risk; reduce lamotrigine dose with valproate (UGT inhibition) and increase dose with enzyme inducers (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin); estrogen-containing contraceptives can lower lamotrigine levels (often requiring dose adjustment); reduce dose in moderate-severe hepatic impairment and consider lower maintenance in significant renal impairment.

How to Take

Oral tablet: swallow with water; may be taken with or without food. Do not chew/crush standard immediate‑release tablets (only chew/disperse if using the chewable/dispersible or ODT formulation).

Side Effects

Common Side Effects

Dizziness, headache, diplopia/blurred vision, nausea/vomiting, somnolence or insomnia, ataxia/loss of coordination, tremor, rash, fatigue.

Safety & Warnings

Contraindications

Contraindication: Hypersensitivity to lamotrigine or to any component of the formulation.

Warnings & Precautions

Warnings/precautions: Strict adherence to slow titration; discontinue at first rash unless clearly not drug-related and do not restart after serious hypersensitivity; increased rash risk with valproate and rapid escalation; monitor for suicidal thoughts/behavior; watch for HLH, DRESS/multiorgan hypersensitivity, and aseptic meningitis; consider interactions with estrogen-containing contraceptives (may lower lamotrigine levels) and adjust dosing; avoid abrupt withdrawal due to seizure risk; consider cardiac risk (conduction/arrhythmias) in patients with underlying heart disease or on sodium-channel-affecting drugs.

Age Restriction

Approved for epilepsy in patients ≥2 years. Not recommended for bipolar disorder under 18 years.

Drug Interactions

Drug Interactions

Key interactions: Valproate increases lamotrigine concentrations (requires lower lamotrigine dosing); enzyme-inducing AEDs (carbamazepine, phenytoin, phenobarbital, primidone) and rifampin decrease lamotrigine concentrations (may require higher dosing); estrogen-containing oral contraceptives decrease lamotrigine concentrations and lamotrigine may reduce levonorgestrel exposure; certain protease inhibitors (e.g., lopinavir/ritonavir, atazanavir/ritonavir) can decrease lamotrigine concentrations.

Interaction Severity

MAJOR: Valproate (markedly increases lamotrigine exposure → higher rash risk; requires lower lamotrigine dosing). MODERATE-MAJOR: Enzyme inducers (carbamazepine, phenytoin, phenobarbital, primidone, rifampin) decrease lamotrigine levels → may require higher dosing. MODERATE: Estrogen-containing contraceptives decrease lamotrigine levels; lamotrigine may reduce progestin (e.g., levonorgestrel) exposure-monitor/adjust. MODERATE: Some HIV protease inhibitor regimens can lower lamotrigine levels. MINOR: Alcohol-additive CNS effects.

Food Interaction

No restriction

Special Populations

Pregnancy

Consult Doctor

Children

Epilepsy (2-12 years, adjunct with valproate): 0.15mg/kg/day for 2 weeks, then 0.3mg/kg/day for 2 weeks, maintenance 1-5mg/kg/day. Epilepsy (2-12 years, with enzyme inducers without valproate): 0.6mg/kg/day for 2 weeks, then 1.2mg/kg/day for 2 weeks, maintenance 5-15mg/kg/day. Not approved for bipolar disorder in patients under 18 years

Elderly

Standard adult dosing, but caution is advised. Lower maintenance doses may be appropriate.

Kidney Impairment

Renal impairment: Use with caution; reduced maintenance doses may be effective in significant renal impairment (including end-stage renal disease), while initial titration is generally per usual schedules unless clinical factors warrant slower titration.

Liver Impairment

Hepatic impairment: Mild-no adjustment; Moderate (Child-Pugh B)-reduce initial, escalation, and maintenance doses by ~25%; Severe (Child-Pugh C) without ascites-reduce by ~25%; Severe with ascites-reduce by ~50%.

Storage & Patient Advice

Storage Conditions

Store below 25°C.

Stopping the Medicine

Do not stop abruptly; if discontinuation is needed, taper gradually over at least 2 weeks when possible (unless safety requires immediate cessation, e.g., rash).

Patient Counseling

Key counseling: take exactly as prescribed with slow titration; do not stop abruptly; report any rash immediately (and seek urgent care if rash with fever, mucosal lesions, facial swelling, or lymphadenopathy); avoid driving until effects known; discuss pregnancy plans; inform clinicians about valproate, enzyme-inducing AEDs, and hormonal contraceptives (may require dose changes); if therapy is interrupted for several days, contact prescriber before restarting.

Monitoring Requirements

No routine serum level monitoring is required; clinically monitor closely for rash (especially early in therapy or after dose increases), hypersensitivity symptoms, suicidality/mood changes, and CNS adverse effects; check hepatic/renal function when clinically indicated (baseline in at-risk patients).

Pharmacology

Duration of Effect

Per dose: approximately 24 hours (supports once- or twice-daily dosing depending on regimen); elimination half-life ~25-33 hours in monotherapy (shorter with enzyme inducers, longer with valproate). Clinical benefit persists with continued daily dosing and is maintained long-term once therapeutic doses are achieved.

Half-Life

Approximately 25-33 hours in adults on monotherapy; ~14 hours with enzyme-inducing antiepileptic drugs (e.g., carbamazepine, phenytoin, phenobarbital/primidone); ~70 hours with valproate.

Bioavailability

~98%

Metabolism

Hepatic metabolism primarily by glucuronidation (UGT-mediated, notably UGT1A4) to inactive metabolites; minimal CYP450 involvement.

Protein Binding

~55%

Product Information

Available Dosage Forms

Tablet, Chewable dispersible tablet, Orally disintegrating tablet, Extended-release tablet.

Composition per Dose

Each tablet: 50mg lamotrigine

Generic Availability

Yes

OTC Alternatives

No OTC alternative

Psych Class

Mood Stabilizer

Controlled Substance

No

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