LAMICTAL 100/MG TAB 30/TAB

Indications

Approved Uses

Epilepsy (adjunctive therapy for partial-onset seizures, primary generalized tonic-clonic seizures, and generalized seizures of Lennox-Gastaut syndrome), Bipolar I Disorder (maintenance treatment to delay the time to occurrence of mood episodes).

Off-Label Uses

Common off-label uses include acute bipolar depression (adjunct/monotherapy in some practices), treatment-resistant unipolar depression (adjunct), certain neuropathic pain syndromes (limited evidence), and migraine prophylaxis (limited/negative evidence).

Dosage & Administration

Dosing by Condition

Dosing is indication- and interaction-specific. Bipolar I maintenance (monotherapy/no interacting meds): 25 mg daily weeks 1-2, 50 mg daily weeks 3-4, 100 mg daily week 5, then 200 mg daily maintenance. Epilepsy adjunct: with valproate-25 mg every other day weeks 1-2, then 25 mg daily weeks 3-4, then gradual increases to typical maintenance 100-200 mg/day; with enzyme-inducing AEDs without valproate-50 mg daily weeks 1-2, then 100 mg/day divided BID weeks 3-4, then increase to typical maintenance 300-500 mg/day (range varies by regimen).

Initial Dose

25mg once daily for 2 weeks (monotherapy or with valproate); 50mg once daily for 2 weeks (with enzyme-inducing AEDs)

Maintenance Dose

Bipolar: 200-400mg/day. Epilepsy: 300-500mg/day. Dose is highly dependent on concomitant medications.

Maximum Dose

700mg/day (with enzyme-inducing AEDs without valproate); 400mg/day (monotherapy); 200mg/day (with valproate); 200mg/day (bipolar disorder)

Children's Dosage

Ages 2-12 years (epilepsy adjunct with valproate): 0.15mg/kg/day for 2 weeks, then 0.3mg/kg/day for 2 weeks, maintenance 1-5mg/kg/day. Ages 2-12 years (adjunct with enzyme-inducing AEDs): 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; dosing must be adjusted for interacting drugs: reduce lamotrigine dose with valproate (inhibits glucuronidation), increase dose with enzyme inducers (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin), and adjust when starting/stopping estrogen‑containing oral contraceptives (can lower lamotrigine levels).

How to Take

Oral use; take with or without food at the same time each day. For standard immediate‑release tablets (e.g., Lamictal 100 mg tablet), swallow whole with water (do not crush/chew unless specifically prescribed a chewable/dispersible or ODT formulation).

Side Effects

Common Side Effects

Dizziness, headache, blurred or double vision, ataxia (loss of coordination), nausea, vomiting, rash, drowsiness, insomnia, tremor.

Side Effect Frequency

Very common (>10%): dizziness, headache, diplopia, nausea, ataxia, blurred vision, somnolence, rash. Common (1-10%): vomiting, diarrhea, insomnia, tremor, fatigue, back pain. Rare/very rare but serious: SJS/TEN, DRESS, aseptic meningitis, HLH, suicidal ideation/behavior.

Safety & Warnings

Contraindications

Contraindication: Known hypersensitivity to lamotrigine or any component of the formulation.

Warnings & Precautions

Warnings/precautions: Serious rash risk (highest early in therapy) mitigated by slow titration and avoiding high starting doses/rapid escalation and valproate coadministration; discontinue for rash unless clearly non-drug-related; monitor for hypersensitivity/DRESS/HLH and aseptic meningitis; monitor for suicidal thoughts/behavior; avoid abrupt withdrawal; use caution and consider ECG/cardiology input in patients with cardiac conduction disease/structural heart disease; use caution in hepatic/renal impairment and adjust dosing as recommended.

Age Restriction

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

Driving Warning

May Cause Drowsiness

Drug Interactions

Drug Interactions

Key interactions: Valproate increases lamotrigine concentrations (requires lower lamotrigine dosing); enzyme inducers (carbamazepine, phenytoin, phenobarbital, primidone, rifampin) decrease lamotrigine concentrations; estrogen-containing oral contraceptives decrease lamotrigine concentrations (and levels may rise during pill-free week); certain HIV protease inhibitor regimens (e.g., lopinavir/ritonavir, atazanavir/ritonavir) can decrease lamotrigine concentrations-monitor/adjust as needed.

Interaction Severity

MAJOR: Valproate/divalproex (markedly increases lamotrigine exposure and serious rash risk-requires lower starting dose and slower titration). MODERATE to MAJOR (clinically significant): Enzyme-inducing AEDs (carbamazepine, phenytoin, phenobarbital, primidone) and rifampin (decrease lamotrigine levels-often requires higher doses); estrogen-containing oral contraceptives (decrease lamotrigine levels; levels rise when stopped-dose adjustments needed); certain HIV protease inhibitor regimens can reduce lamotrigine levels. MINOR/none: antacids have no meaningful effect.

Special Populations

Children

Ages 2-12 years (epilepsy adjunct with valproate): 0.15mg/kg/day for 2 weeks, then 0.3mg/kg/day for 2 weeks, maintenance 1-5mg/kg/day. Ages 2-12 years (adjunct with enzyme-inducing AEDs): 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

No specific dose adjustment required based on age alone; however, titrate cautiously given potential for polypharmacy interactions and reduced renal/hepatic function; monitor closely

Kidney Impairment

Renal impairment: Use with caution; reduced maintenance doses may be effective in significant renal impairment/end-stage renal disease; no single universal max dose applies-dose should be individualized (including in dialysis) based on response and tolerability.

Storage & Patient Advice

Stopping the Medicine

Do not stop abruptly; taper gradually over at least 2 weeks (unless safety requires rapid discontinuation, e.g., serious rash).

Overdose

Overdose: Symptoms may include ataxia, nystagmus, dizziness/drowsiness, seizures, decreased level of consciousness/coma, and cardiac conduction abnormalities (e.g., QRS widening/intraventricular conduction delay); management is supportive with airway/ventilation and cardiac monitoring, consider activated charcoal if early, and seek emergency care (hemodialysis may be considered in severe cases).

Patient Counseling

Key counseling: take exactly as titrated (do not increase faster); do not stop abruptly; report any rash or hypersensitivity symptoms (fever, swollen glands, mucosal sores) immediately; caution with dizziness/drowsiness and driving/alcohol; discuss pregnancy/contraceptives and notify provider before starting/stopping estrogen-containing OCPs; report mood changes/suicidal thoughts; if therapy is interrupted for several days, contact prescriber as re-titration may be required.

Monitoring Requirements

No routine serum level monitoring is required; monitor closely for rash (especially during early titration), hypersensitivity symptoms, mood changes/suicidal ideation, and clinical response (seizure control or mood stability). Consider baseline/periodic hepatic/renal assessment when clinically indicated and review interacting medications (e.g., OCP changes).

Pharmacology

Mechanism of Action

Blocks voltage-sensitive sodium channels, stabilizing neuronal membranes and reducing repetitive firing; decreases presynaptic release of excitatory amino acids (e.g., glutamate/aspartate).

Onset of Action

Clinical benefit is gradual due to required titration: seizure control may improve over days to weeks; mood benefits in bipolar disorder typically take several weeks.

Metabolism

Primarily hepatic metabolism via glucuronidation (mainly UGT1A4; also UGT2B7); minimal CYP450 involvement.

Excretion

Primarily renal excretion of metabolites (mainly glucuronide conjugates); minimal unchanged drug; small fecal component.

Product Information

Available Dosage Forms

Tablet, Chewable Dispersible Tablet, Orally Disintegrating Tablet, Extended-Release Tablet.

Composition per Dose

Each tablet: 100mg lamotrigine

Generic Availability

Yes

OTC Alternatives

No OTC alternative

Psych Class

Mood Stabilizer

Controlled Substance

No

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