Which drug is the preferred choice for treating absence (petit mal) seizures?

The preferred choice for treating absence (petit mal) seizures is ethosuximide. Ethosuximide specifically targets absence seizures by reducing the frequency of these episodes, which occur due to abnormal electrical activity in the brain characterized primarily by a brief loss of consciousness.

Ethosuximide works by inhibiting T-type calcium channels in the thalamic neurons, which is crucial for the generation of the typical spike-and-wave discharges observed in absence seizures. This mechanism directly addresses the underlying cause of absence seizures, making it the most effective and commonly used medication for this type of seizure.

In contrast, phenytoin is primarily effective for tonic-clonic seizures and does not address the specific mechanism of absence seizures, often resulting in ineffective treatment when used for this condition. Primidone, while useful for various seizure types, is not considered the first-line treatment for absence seizures. Valproic acid is also used to treat various seizures, including absence seizures, but it is more broadly used and not as specifically tailored as ethosuximide for this particular type. Therefore, ethosuximide remains the primary choice due to its targeted action and efficacy in treating absence seizures.