Which drug is the correct choice for absence seizures?

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

Answer: (D)

Absence seizures arise from abnormal thalamocortical oscillations, producing a characteristic 3 Hz spike-and-wave pattern on EEG. Ethosuximide specifically dampens these rhythms by inhibiting T-type calcium channels in thalamic neurons, reducing the low-threshold calcium currents that sustain the burst firing behind absence seizures. This makes it the drug of choice for absence seizures. Other options either act mainly on sodium channels (phenytoin, carbamazepine) and are not effective for absence—and can sometimes worsen it—or, while valproic acid is broad-spectrum and can treat absence, it carries a wider side-effect profile and is not as targeted for pure absence.