Lamotrigine (Brand Names in India: Lametec, Lamitor, Lamictal)

1. Generic Name

Lamotrigine

2. Brand Names

• Lametec (Cipla)
• Lamitor (Torrent Pharmaceuticals)
• Lamictal (GlaxoSmithKline)

3. Pharmaceutical Formulation

• Tablets: 25 mg, 50 mg, 100 mg, 200 mg
• Chewable Dispersible Tablets: 5 mg, 25 mg

4. Therapeutic Classification

Anticonvulsant / Mood Stabilizer

5. Indications

Lamotrigine is indicated for:

• Epilepsy:
  • Partial seizures
  • Generalized tonic-clonic seizures
  • Seizures associated with Lennox-Gastaut syndrome
• Bipolar Disorder: Maintenance therapy to delay the occurrence of mood episodes (particularly depressive episodes) in adults.

6. Mechanism of Action

Lamotrigine inhibits voltage-sensitive sodium channels, stabilizing neuronal membranes and reducing the release of excitatory neurotransmitters like glutamate and aspartate. This contributes to its anticonvulsant and mood-stabilizing effects.

7. Dosage and Administration

Epilepsy (Adults and Children ≥12 years):

• Monotherapy: Start with 25 mg/day for 2 weeks, increase to 50 mg/day for weeks 3 and 4, then adjust to 100-200 mg/day.
• Adjunctive Therapy (with enzyme-inducing drugs like carbamazepine): Start with 50 mg/day for 2 weeks, then titrate to 100-400 mg/day.

Bipolar Disorder (Adults):

• Initial Dose: 25 mg/day for 2 weeks, then increase to 50 mg/day for weeks 3 and 4, and 100 mg/day in week 5.
• Maintenance Dose: 200 mg/day.

Pediatric Use: Dosage adjustments are weight-dependent.

Note: Dose adjustments are required for patients on valproate or enzyme-inducing drugs.

8. Onset of Action

• Epilepsy: Seizure control may be achieved within 1-2 weeks after reaching an effective dose.
• Bipolar Disorder: Full mood stabilization effects may take several weeks to months.

9. Contraindications

• Hypersensitivity to lamotrigine or its excipients.
• History of serious skin reactions such as Stevens-Johnson syndrome with lamotrigine use.

10. Warnings and Precautions

• Serious Skin Reactions: Risk of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis; slow titration is essential.
• Aseptic Meningitis: Rare, but monitor for symptoms.
• Suicidality: Increased risk in patients taking anticonvulsants; monitor closely.
• Hepatic or Renal Impairment: Dose adjustment may be required.
• Contraceptive Use: Hormonal contraceptives may reduce lamotrigine levels.

11. Side Effects

Common:

• Dizziness, headache, ataxia
• Nausea, vomiting
• Diplopia, blurred vision
• Somnolence, fatigue

Serious:

• Stevens-Johnson Syndrome (SJS)
• Toxic Epidermal Necrolysis (TEN)
• Aseptic meningitis
• Blood dyscrasias

12. Drug Interactions

• Valproate: Increases lamotrigine levels; dose adjustment required.
• Enzyme-inducing drugs (e.g., carbamazepine, phenytoin): Decrease lamotrigine levels; higher doses may be needed.
• Oral Contraceptives: May reduce lamotrigine efficacy; adjust dose accordingly.
• Serotonergic Drugs: Risk of serotonin syndrome.

13. Overdose Management

Symptoms: Dizziness, ataxia, nystagmus, seizures, coma.
Treatment: Symptomatic and supportive care. No specific antidote is available. Hemodialysis may aid in drug removal.

14. Pharmacokinetics

• Absorption: Rapidly absorbed; bioavailability ~98%.
• Distribution: Moderate protein binding (~55%).
• Metabolism: Hepatic glucuronidation.
• Elimination: Primarily renal; half-life ~25-33 hours (longer with valproate, shorter with enzyme inducers).

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15. Storage and Handling

Store at a temperature below 30°C, protected from light and moisture. Keep out of reach of children.

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16. Packaging

Available in blister packs of 10, 20, or 30 tablets.

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17. Manufacturer Information

• Lametec: Cipla
• Lamitor: Torrent Pharmaceuticals
• Lamictal: GlaxoSmithKline