Which drug is specifically used to treat absence seizures?

The drug specifically used to treat absence seizures is ethosuximide. Absence seizures, characterized by brief lapses in consciousness often accompanied by subtle motor signs, primarily occur in children. Ethosuximide works by decreasing the frequency of these seizures through its action on T-type calcium channels in the thalamic neurons, which is crucial for generating the 3Hz spike-and-wave discharges typical of absence seizures. By reducing the excitability of these neurons, ethosuximide effectively prevents the occurrence of these seizures.

In contrast, other options such as carbamazepine and phenytoin are generally effective for focal and generalized tonic-clonic seizures but are not suitable for absence seizures, as they may even exacerbate them. Valproic acid can be used for a broader spectrum of seizure types, including absence seizures, but it is not the first-line treatment specifically designated for this type. Ethosuximide remains the drug of choice due to its efficacy and specific targeting of the underlying mechanisms of absence seizures.