Zarontin (ethosuximide) has been used for many years to treat children with absence seizures. Side effects are usually mild, most often gastrointestinal upsets that can be minimized by taking doses with meals, up to three times a day.

The initial dose for patients 3 to 6 years of age is one capsule or one teaspoon of syrup (250 mg) per day. Children over 6 years can start with two capsules or two teaspoons of syrup (500 mg) per day. The dose thereafter must be individualized by small increments according to the patient's response. One useful method is to increase the daily dose by 250 mg every 4 to 7 days until control is achieved with minimal side effects.

The optimal daily dose for most children is 20 mg/kg. This dose has given average plasma levels within the accepted therapeutic range of 40 to 100 mcg/mL.

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