Question

Which adverse effect is most characteristically associated with the antiepileptic drug lamotrigine?

• A. Severe cutaneous reactions including Stevens-Johnson syndrome / dizziness
• B. Marked dose-independent hepatotoxicity
• C. Gingival hyperplasia
• D. Irreversible visual field constriction

Hint:

Slow-titrated AED feared for skin rash and SJS, especially with valproate.

Answer 1

The Correct Option is A

Step 1: Recall the signature toxicity of lamotrigine, a broad-spectrum antiepileptic that blocks voltage-gated sodium channels and reduces glutamate release.

Step 2: Its most feared and most characteristic adverse effect is a rash, ranging from benign maculopapular eruptions to life-threatening Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). The risk is highest with rapid dose escalation and with co-administration of valproate (which inhibits lamotrigine metabolism) - hence the mandated slow titration. Common dose-related CNS effects include dizziness, diplopia, headache and ataxia.

Step 3: Why the other options are wrong - serious hepatotoxicity is the hallmark of valproate (and felbamate), not lamotrigine. Gingival hyperplasia is classic for phenytoin. Irreversible visual field constriction is the signature toxicity of vigabatrin.

Key fact: Lamotrigine to skin rash / SJS-TEN (titrate slowly, risk increased by valproate); dizziness is a common dose-related effect.