This medication is used for the management and prevention of certain types of seizures (those caused by absence [petit mal] epilepsy). It may be used at the same time as other medications that are used to control different types of seizures. It helps to control seizures by working in the central nervous system.

Your doctor may choose to use a medication for conditions other than the ones listed in these drug information articles. If you're unsure why you are taking this medication, contact your doctor.

Adults: The dose of ethosuximide varies according to the needs and age of the person using the medication and their response to treatment. Often a dose of 1 g to 1.5 g daily in divided doses controls seizures in adults.

Children: The dose for children three to six years of age is 250 mg daily; for older children, it is 500 mg daily, taken in divided doses.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is very important that this medication be taken on a regular schedule as prescribed by the doctor. If you miss a dose of this medication, take it as soon as you remember it. If it is almost time for your next dose, skip the missed dose and carry on with your regular schedule. Do not double-up on doses.

Zarontin^® is available as capsules and as a liquid.

Capsules: Each soluble, gelatin capsule, marked "PD 237", contains ethosuximide 250 mg. Nonmedicinal ingredients: D&C Yellow No. 10, FD&C Red No. 3, gelatin, glycerin, polyethylene glycol, and sorbitol.

Syrup: Each 5 mL contains ethosuximide 250 mg. Nonmedicinal ingredients: alcohol, citric acid, FD&C Yellow No. 6, flavouring agents, glycerin, purified water, saccharin sodium, sodium benzoate, sodium citrate, sucrose, and vanillin. Alcohol: 3%. Sodium: <1 mmol (6.7 mg)/5 mL. This medication does not contain gluten, lactose, parabens, sulfite, or tartrazine.

Ethosuximide should not be used by people allergic to ethosuximide or to any of the ingredients of the medication or to any of the medications in the family of succinimides (such as methsuximide).

The following side effects may go away as your body becomes used to the medication; check with your doctor if they continue or become bothersome.

More common:

• clumsiness or unsteadiness
• dizziness
• drowsiness
• headache
• hiccups
• loss of appetite
• nausea or vomiting
• stomach cramps

  Less common:

• irritability

Check with your doctor as soon as possible if any of the following side effects occur:

More common:

• muscle pain
• skin rash and itching
• swollen glands
• sore throat and fever

  Less common:

• aggressiveness
• depression
• difficulty concentrating
• nightmares

  Rare:

• chills
• increased chance of certain types of seizures
• mood or mental changes
• nosebleeds or other unusual bleeding or bruising
• shortness of breath
• sores, ulcers, or white spots on lips or in mouth
• unusual tiredness or weakness
• wheezing, tightness in chest, or difficulty breathing

Other side effects not listed above may occur in some people. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Lupus: Cases of systemic lupus erythematosus have been reported with the use of ethosuximide.

Medical conditions: Ethosuximide should be taken with extreme caution by people with liver disease or kidney disease.

Occupational hazards: Ethosuximide may impair the mental or physical abilities required for potentially dangerous activities such as driving or operating machinery. People taking this medication should determine how it affects them before undertaking such activities.

Pregnancy: Women subject to major seizures should not stop using this medication during pregnancy. For women subject to minor seizures, the risk of stopping the medication prior to or during pregnancy should be weighed against the risk of birth defects. If you become pregnant while taking this medication, contact your right away.

Breast-feeding: Women who take ethosuximide should not breast-feed their infants.

Children: The safety and effectiveness of this medication have not been established for children under three years of age.

• valproic acid

Ethosuximide may affect how the following medications work:

• lamotrigine
• phenytoin
• primidone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.