Which is the most appropriate first-line treatment for absence seizures?

• A. Ethosuximide
• B. Valproate
• C. Carbamazepine
• D. Lamotrigine

Answer: (A)

Absence seizures are driven by abnormal rhythmic activity in thalamocortical circuits, largely due to T-type calcium channel activity in thalamic relay neurons. Ethosuximide directly inhibits these T-type calcium channels, which interrupts the specific burst firing that underlies absence seizures. This targeted action makes ethosuximide the most effective and appropriate first-line choice for treating typical absence seizures, with a favorable safety profile compared with other options.

Valproate can treat absence as well, but it carries higher risks (notably hepatotoxicity and teratogenicity), so it’s often reserved for broader seizure types or when ethosuximide isn’t suitable. Carbamazepine is more effective for focal seizures and can worsen absence. Lamotrigine is useful for a range of seizures but is not as effective as ethosuximide for pure absence and is typically used as add-on or for other seizure types.