Ethosuximide, an anticonvulsant drug

Ethosuximide, an anticonvulsant drug

Ethosuximide, USP is an anticonvulsant succinimide, chemically designated as alpha-ethyl-alphamethyl-succinimide. Ethosuximide, also known as Zarontin, is a medicine that has been approved by the Food and Drug Administration to treat absence (petit mal) seizures in both adults and children.

Ethosuximide, an anticonvulsant drug

• Ethosuximide is available in brand and generic form. The tablets may look different, depending on the company that makes them.

• Sometimes seizure medicines are used for other conditions. The dose of ethosuximide may vary depending on why the medicine is being given and if it is given alone or with other medicines. It is important to follow the exact directions given to you by your doctor.

• Always check the appearance of the tablets with the pharmacist when the prescription is filled to be certain you are given the right medication.

Therapeutic: anticonvulsants

Used for: Absence seizures. (Typical absence seizures respond better than atypical absence seizures).

Mechanism of action

Ethosuximide suppresses the paroxysmal three cycle per second spike and wave activity associated with lapses of consciousness which is common in absence (petit mal) seizures. The frequency of epileptiform attacks is reduced, apparently by depression of the motor cortex and elevation of the threshold of the central nervous system to convulsive stimuli.



Ethosuximide is contraindicated in patients with hypersensitivity to succinimides, ethosuximide or any components of this medication.


People with mixed types of seizures may get increased generalized tonic-clonic (grand mal) seizures if using ethosuximide alone. Inform your doctor if you are a person with liver or kidney disease or lung problems, or a hypersensitivity to succinimides. Use caution when operating machinery or driving automobiles.


Recommended initial daily dose for children and adults is approximately 20-30 mg/kg administered in two divided doses. This regimen will frequently achieve plasma levels in the therapeutic range of 40-100 mg/L (optimum 75 mg/L). As the dose serum level relationship may be curvilinear in individual patients dosage should be increased by small increments. One useful method is to increase the daily dose by 250 mg every four to seven days until control is achieved with minimal side effects.

Dosages exceeding 1.5 g daily, in divided doses should be administered only under the strictest supervision of the physician. Plasma level monitoring is recommended. ZARONTIN may be administered in combination with other anticonvulsants when other forms of epilepsy coexist with petit mal.

In Pregnancy:

Anti-epileptic medications do slightly increase the risk of fetal abnormalities. Women who are considering pregnancy should first consult their doctor. Ethosuximide freely enters the breastmilk. Consult your physician before breastfeeding if you are taking this drug.


Abrupt withdrawal of any anti-epileptic medication may trigger status epilepticus, a potentially fatal condition of continued seizures without recovery. When there is a need for reduction, discontinuation or substitution of the medication, this should be done gradually and under the physician’s care. Never discontinue anti-epileptic medications or make changes in activities unless specifically advised to do so by an attending physician.

What side effects may occur?

Side effects may occur with any medicine. Some side effects will go away on their own or when the dose of medicine is changed. Others may be more serious and mean that your body is not tolerating the drug. Tell your doctor about all side effects that occur, but do not stop taking the medicine without advice from your doctor.

Common: Upset stomach, loss of appetite, diarrhea, sleepy, dizzy, nervous, irritable, agitated.

Does this medicine affect birth control pills?

Contraceptives or birth control that contain the hormones estrogen or progesterone (such as birth control pills, injections or patches) may not work completely to prevent pregnancy when a woman is also taking ethosuximide.

The dose of contraceptive may need to be increased or injections given more frequently. Talk to your doctor if you start or stop hormonal birth control and for specific instructions on the dose of birth control. Other forms of birth control, such as barrier methods, may also be suggested. Call your doctor if you have any signs of breakthrough bleeding or symptoms of pregnancy.


Effects on Ability to Drive and Use Machines

Ethosuximide may impair the mental/and or physical abilities required for the performance of potentially hazardous tasks, such as driving, using machinery or other such activity requiring alertness.



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