Lamotrigine Bristol Labs (Lamotrigine)

Lamotrigine is an anticonvulsant that modulates neuronal excitability in several neurological and psychiatric conditions.

• Epilepsy: reduces the frequency of focal and generalized seizures when used as monotherapy or adjunct therapy.
• Bipolar disorder: maintains mood stability and prevents recurrence of depressive and manic episodes in adult patients.
• Lennox‑Gastaut syndrome (as adjunct): helps lower seizure burden in this severe childhood epilepsy.

• Lamotrigine inhibits voltage‑gated sodium channels, stabilising neuronal membranes and decreasing the release of excitatory neurotransmitters such as glutamate. This reduction in neuronal firing underlies its antiepileptic and mood‑stabilising effects.

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

Common Side Effects

• Dizziness: transient sensation of light‑headedness.
• Headache: mild to moderate intensity.
• Nausea: occasional gastrointestinal upset.
• Rash: skin redness or itching, often mild.
• Blurred vision: temporary visual disturbances.
• Fatigue: feeling unusually tired.

Serious or Rare Side Effects

• Stevens‑Johnson syndrome: severe skin reaction requiring immediate medical attention.
• Toxic epidermal necrolysis: life‑threatening skin detachment.
• Blood dyscrasias: including agranulocytosis or aplastic anaemia.
• Hepatic failure: signs of liver dysfunction.
• Suicidal thoughts: emergence of depressive ideation.
• Severe skin reactions: such as drug reaction with eosinophilia and systemic symptoms (DRESS).

When prescribing lamotrigine, clinicians should consider several safety measures.

• Monitor skin reactions: discontinue immediately if a rash appears and assess for severe cutaneous adverse reactions.
• Adjust dose in renal impairment: reduce dosage according to renal function to avoid accumulation.
• Avoid abrupt discontinuation: taper gradually to minimise seizure recurrence.
• Use caution in pregnancy: potential risk to the fetus is not well defined; weigh benefits against risks.
• Review concomitant valproate: co‑administration may increase lamotrigine levels and require dose reduction.
• Store at room temperature: keep in the original packaging, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Valproic acid: markedly raises lamotrigine levels, requiring dose reduction.
• Carbamazepine: significantly lowers lamotrigine concentrations, potentially reducing efficacy.
• Phenytoin: decreases lamotrigine exposure, may necessitate dose increase.
• Phenobarbital: reduces lamotrigine levels, affecting seizure control.
• Oral contraceptives: increase lamotrigine clearance, possibly diminishing therapeutic effect.

Moderate Interactions (Monitor Closely)

• Serotonergic agents (e.g., SSRIs): may increase risk of serotonin syndrome.
• Other antiepileptics (e.g., levetiracetam): monitor for additive side‑effects.
• NSAIDs: watch for enhanced rash risk.