Question

Ethosuximide is the drug of choice for:

• A. Generalized tonic clonic seizures
• B. Complex partial seizures
• C. Absence seizures
• D. Myoclonic seizures

Hint:

Think about which drug blocks thalamic T-type calcium channels and treats only one specific seizure type.

Answer 1

The Correct Option is C

Step 1: Identify the drug. Ethosuximide is a succinimide antiepileptic that works by blocking T-type calcium channels in thalamic neurons.
Step 2: Link the mechanism to the seizure type. Absence (petit mal) seizures arise from abnormal 3 Hz spike-and-wave thalamocortical oscillations that depend on T-type \(Ca^{2+}\) currents. By blocking these channels, ethosuximide stops the rhythm, so it is the drug of choice for absence seizures.
Step 3: Rule out the wrong options. Generalized tonic clonic seizures (A) respond to valproate, phenytoin, or carbamazepine, not ethosuximide. Complex partial seizures (B) are best treated with carbamazepine. Myoclonic seizures (D) need valproate or levetiracetam, and ethosuximide can even worsen them.
Step 4: Note that valproate also covers absence seizures, but ethosuximide is preferred when absence is the only seizure type because it has fewer systemic side effects.
Answer: Option C (Absence seizures).