Which medications are considered first-line for absence seizures?

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

Answer: (A)

Absence seizures arise from abnormal thalamocortical oscillations, so treatments that dampen this rhythm are first-line. Ethosuximide directly blocks T-type calcium channels in thalamic neurons, which reduces the 3-Hz spike-and-wave activity that produces the brief lapses in consciousness. Valproic acid is also effective and is used when there are multiple seizure types or if ethosuximide isn’t suitable; it provides broad anti-seizure activity through multiple mechanisms, including increasing GABA and stabilizing neural firing. In contrast, phenytoin and carbamazepine target sodium channels and are more effective for focal seizures; they can worsen absence seizures or offer little benefit. Gabapentin isn’t effective for absence and isn’t a first-line choice.