Ethosuximide (Zarontin)

When is ethosuximide used ?

Ethosuximide is used only to treat absence (petit mal) seizures, particularly in young children. It does not clearly help (and may even worsen) most other types of seizures.

What are the most common side effects of ethosuximide ?

Many people who take ethosuximide have no trouble with side effects. The most common complaints include upset stomach, loss of appetite, or diarrhea. These problems are usually mild and often go away by themselves. If they persist or are really bothersome, call the doctor. Usually reducing the amount of ethosuximide or taking it with meals will help. Never stop taking ethosuximide nor reduce the dose without first consulting with the doctor. A few people become sleepy or dizzy when they take ethosuximide, so those who have just started taking it should be careful during activities that might be dangerous, until they know how it affects them.

Allergic reactions

Some people who take ethosuximide develop a red rash within the first few weeks of taking it. If this happens, tell the doctor or nurse right away, to be sure that it's not the beginning of a serious problem. It is very rare for the rash to become serious, but no rash should be ignored. Often, the rash is a sign that ethosuximide needs to be switched to a different seizure medicine.

What are the most serious side effects of ethosuximide ?

Serious reactions to ethosuximide are very rare. However, everyone who takes this medicine should at least be aware of them. If you notice any of these symptoms, call your doctor right away, but do not stop using the ethosuximide unless the doctor says so:

  • Rash
  • Sore throat, fever, sores in the mouth, or easy bruising (could mean a blood problem)
  • Fever, rash, arthritis, swelling in the lymph nodes (could mean an autoimmune disorder)
  • Depression, anxiety, or aggressiveness
  • Hallucinations, hearing "voices" or losing contact with reality

Who should not take ethosuximide ?

The only people who definitely should not take ethosuximide are those who are allergic to it or to other medicines in the same family, called succinimides. The other common medicine in this family is Celontin (methsuximide).

People who have liver or kidney disease need to be extra cautious about taking ethosuximide. Most of them can take it successfully, however, if they work with the doctor to determine the correct amount to take. That is why it is so important to make sure the doctor knows about liver disease, other medical problems and all current medications the patient is taking.

Can ethosuximide be taken with other medications ?

Sometimes one kind of medicine changes the way another kind of medicine works in the body. This is true not only for prescription medicines, but also for over-the-counter medicines in the local drug store. It's also true for herbal products, vitamins, a few kinds of food, and even cigarettes!

Any time a doctor suggests a new medication, be sure to report the other medicines you are already using. If two kinds of medicine affect each other, the doctor may want to prescribe something else or change the amount to be taken.

Ethosuximide is less likely than many other seizure medicines to interact with other medications. The most important thing to know is that the level of ethosuximide in the blood is reduced if it is taken along with certain other seizure medicines. The amount of ethosuximide taken may need to be increased if you start taking any one of these medicines:

  • Carbamzepine (Tegretol, Carbatrol)
  • Phenytoin ( Dilantin, Phenytek)
  • Primidone (Mysoline)
  • Phenobarbital

If a woman takes ethosuximide during pregnancy,will it hurt the baby ?

In the United States, the Food and Drug Administration (FDA) assigns each medication to a "Pregnancy Category" according to whether it has been proven to be harmful in pregnancy. Ethosuximide is listed in Pregnancy Category C. This means that women should be cautious, but sometimes the benefits may outweigh the risks. In fact, a large majority of women who use ethosuximide during pregnancy have normal, healthy babies.

Women with epilepsy who are pregnant or thinking about becoming pregnant should talk to their doctor about their seizure medicines. Taking more than one seizure medicine may increase the risk of birth defects, so doctors sometimes gradually reduce the number or amount of seizure medicines taken by women planning for pregnancy. This is not done routinely, however, because it increases the risk of seizures. Some kinds of seizures can injure the baby, so women should not stop using seizure medicines or reduce the amount they take unless recommended by their doctor.

All women who are capable of becoming pregnant should take at least 0.4 mg (400 mcg) of the vitamin called folic acid every day because it helps to prevent specific birth defects called Neural Tube Defects. (The most well-known of these is spina bifida, in which the spinal cord is not completely enclosed.) Women with epilepsy should take between 1 and 4 mg of folic acid daily during their reproductive years. If the doctor thinks a woman is at especially high risk, the larger dose of folic acid—4 mg (4000 mcg) per day—may be recommended, beginning before the woman becomes pregnant.

Some babies born to mothers taking antiepileptic medications have had inadequate blood clotting within the first 24 hours after birth. It is often recommended that the mother be given 10 to 20 mg of vitamin K per day during the last month of pregnancy to prevent this problem.

About 20% to 35% of women have seizures more often during pregnancy because of changes in hormones or changes in how their seizure medicine is handled by the body. It is helpful for the doctor to check the levels of medicine in the blood regularly during pregnancy so that the dosage can be adjusted if necessary.

Ethosuximide in the mother’s blood passes nearly completely into the breast milk, however, how much of this actually enters the baby’s bloodstream is not known. Further, how ethosuximide affects the baby is unknown. That said, it is strongly felt by neurologists and epileptologists that the benefits of breastfeeding largely outweigh the risks of exposing the baby to antiepileptic medications, including ethosuximide. As a matter of fact, the American Academy of Neurology and the American Epilepsy Society both recommend breastfeeding in women with epilepsy.

Please click here for more information about family planning, pregnancy, and breastfeeding in women with epilepsy.