Drug of choice for absence seizures?

• A. Phenytoin
• B. Carbamazepine
• C. Valproic acid
• D. Ethosuximide

Answer: (D)

Absence seizures arise from abnormal thalamocortical oscillations that rely on low-threshold T-type calcium channels in thalamic neurons. Ethosuximide targets these channels, reducing the T-type calcium currents and dampening the rhythmic bursts that produce absence seizures. This focused mechanism makes it highly effective for absence seizures and usually with a gentler cognitive side‑effect profile, so it’s the preferred first-line treatment for this seizure type.

Phenytoin and carbamazepine are sodium-channel blockers suited to focal or generalized tonic-clonic seizures; they don’t address the thalamocortical bursts that underlie absence and can even worsen absence symptoms. Valproic acid is effective against multiple seizure types, including absence, but carries higher risks such as hepatotoxicity and teratogenicity, especially in women of childbearing potential.