Zarontin (ethosuximide) generally is used only for absence seizures. It is highly effective and safe for treating childhood absence epilepsy, which occurs in 8% of children with epilepsy between ages 5 and 14 years. This disorder usually begins between ages 4 and 8 in children without previous brain disorders. Often there is a family history of the same disorder. These seizures almost always can be provoked in the office by having the child hyperventilate for a few minutes. Although these seizures usually will stop when the child gets older, children who have them need effective treatment to avoid learning problems and accidental injuries.

Zarontin is often the first-line medication for childhood absence epilepsy. In one early study, 95% of patients had the number of seizures reduced by at least half, and about half the patients had them reduced by at least 90%.

Some children who have absence seizures have more complicated disorders that are harder to treat and may not be outgrown, such as "atypical absence" or juvenile myoclonic epilepsy. These children may also have other types of seizures, are often older when the absence seizures begin, and have a different EEG pattern than children with typical childhood absence epilepsy. Zarontin is also effective in controlling absence seizures in many of these children, but other medications often are needed to control other types of seizures. Depakote and other valproate medications will control absence seizures, so it may be used instead of Zarontin. Some children do best with a combination of these two.

Zarontin can also be used in combination therapy for patients who have both absences and other kinds of seizures. No single combination of antiepileptic medications is perfect for everyone. Sometimes, a series of combinations must be tried before finding what is best for the individual patient. Adding Zarontin usually does not affect the level of other seizure medicines in the body, but some adjustment of the Zarontin dosage may be needed if other medications are added.

Reviewed February 2004 by Barry Gidal, PharmD, epilepsy.com Editorial Board.