Lamotrigine Arrow Lab (Lamotrigine)

• Lamotrigine is an anticonvulsant that acts on neuronal sodium channels to manage seizure disorders and mood stabilization.
• Partial seizures (epilepsy): reduces frequency and severity of seizure episodes.
• Generalized seizures (epilepsy): used as adjunctive therapy to improve overall seizure control.
• Bipolar disorder (maintenance): stabilises mood and helps prevent depressive and manic relapses.

• Lamotrigine blocks voltage‑gated sodium channels in neuronal membranes, decreasing the rapid influx of sodium ions during depolarisation. This stabilises neuronal excitability and limits the release of excitatory neurotransmitters such as glutamate and aspartate, thereby reducing the propagation of abnormal electrical activity that underlies seizures and mood swings. The inhibition is use‑dependent, meaning it preferentially affects neurons that fire rapidly, which contributes to its efficacy in both epilepsy and bipolar disorder.

Lamotrigine may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Dizziness: sensation of light‑headedness or unsteadiness.
• Headache: mild to moderate pain in the head.
• Nausea: feeling of stomach upset.
• Rash: mild skin irritation or redness.

Serious or Rare Side Effects

• Stevens‑Johnson syndrome: severe skin reaction with blistering and mucosal involvement.
• Aseptic meningitis: inflammation of the meninges without infection.
• Blood dyscrasias: rare cases of agranulocytosis or aplastic anemia.

Before prescribing lamotrigine, clinicians should consider several safety measures and patient factors.

• Dose titration: increase gradually to minimise rash risk.
• Skin reactions: monitor for any rash and discontinue if severe.
• Renal impairment: adjust if significant kidney dysfunction is present.
• Concomitant valproate: be aware of increased lamotrigine levels requiring lower initial dose.
• Store at ambient temperature: keep below 25°C in original packaging, protect from moisture.

Lamotrigine interacts with several medicines that can alter its plasma concentration.

Major Interactions (Avoid)

• Valproic acid: markedly increases lamotrigine levels; avoid co‑administration without dose adjustment.
• Carbamazepine: reduces lamotrigine concentrations, potentially decreasing efficacy.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: lower lamotrigine levels, may require dose increase.
• Phenobarbital: decreases lamotrigine levels, monitor seizure control.
• Phenytoin: reduces lamotrigine concentrations, consider therapeutic monitoring.