Lamotrigine

• Focal and generalised epilepsy in pregnancy
• Bipolar depression maintenance in pregnancy

Inhibits use-dependent voltage-gated Na⁺ channels → stabilises presynaptic membranes → ↓ glutamate release.

• Clearance ↑ 65-230% by T3
• Slow titration mandatory (SJS risk)
• Restart baseline dose within 3 days post-partum

Adult start

25 mg OD × 2 wk → 50 mg OD × 2 wk → titrate to 100–400 mg/day

Pregnancy

Check trough levels monthly; may need to double preconception dose by T3

Postpartum

Return to preconception dose over 3–7 days

• AbsoluteHistory of hypersensitivity to lamotrigine

• Rash — including Stevens-Johnson & TEN (0.1%, higher on rapid titration)
• Headache, diplopia
• Tremor, ataxia at high dose
• Insomnia

• • Major malformation rate 2.0–2.9% (background 2%) — the safest major AED
• • No signal for neurodevelopmental impairment
• • Monotherapy strongly preferred

• Valproate

  Avoid

  Doubles lamotrigine levels — halve dose, extra SJS risk

• Combined oral contraceptive

  Avoid

  ↓ lamotrigine level ~50%

• Carbamazepine / phenytoin

  Caution

  ↓ lamotrigine level

• 💡 Any new rash in first 8 weeks → stop and review urgently
• 💡 Pre-conception folate 5 mg/day for all women on AEDs