Brand Name(s):

• Celontin®

WHY is this medicine prescribed?

Methsuximide is used to control absence seizures (petit mal; a type of seizure in which there is a very short loss of awareness during which the person may stare straight ahead or blink his eyes and does not respond to others) that cannot be treated with other medications. Methsuximide is in a class of medications called anticonvulsants. It works by decreasing abnormal electrical activity in the brain.

HOW should this medicine be used?

Methsuximide comes as a capsule to take by mouth. It is usually taken one or more times a day. Take methsuximide at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take methsuximide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor will probably start you on a low dose of methsuximide and gradually increase your dose, not more often than once a week.

Methsuximide may help control your condition but will not cure it. Continue to take methsuximide even if you feel well. Do not stop taking methsuximide without talking to your doctor, even if you experience side effects such as unusual changes in behavior or mood. If you suddenly stop taking methsuximide, your seizures may worsen. Your doctor will probably decrease your dose gradually.

Are there OTHER USES for this medicine?

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking methsuximide,

• tell your doctor and pharmacist if you are allergic to methsuximide, ethosuximide (Zarontin), or any other medications.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention antidepressants; other medications for seizures such as phenobarbital and phenytoin (Dilantin); medications for pain; sedatives; sleeping pills; and tranquilizers. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had mental illness or kidney or liver disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking methsuximide, call your doctor.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking methsuximide.
• you should know that this medication may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.
• talk to your doctor about the safe use of alcohol while you are taking this medication.
• you should know that your mental health may change in unexpected ways and you may become suicidal (thinking about harming or killing yourself or planning or trying to do so) while you are taking methsuximide. A small number of adults and children 5 years of age and older (about 1 in 500 people) who took anticonvulsants such as methsuximide to treat various conditions during clinical studies became suicidal during their treatment. Some of these people developed suicidal thoughts and behavior as early as one week after they started taking the medication. There is a risk that you may experience changes in your mental health if you take an anticonvulsant medication such as methsuximide, but there may also be a risk that you will experience changes in your mental health if your condition is not treated. You and your doctor will decide whether the risks of taking an anticonvulsant medication are greater than the risks of not taking the medication. You, your family, or your caregiver should call your doctor right away if you experience any of the following symptoms: panic attacks; agitation or restlessness; new or worsening irritability, anxiety, or depression; acting on dangerous impulses; difficulty falling or staying asleep; aggressive, angry, or violent behavior; mania (frenzied, abnormally excited mood); talking or thinking about wanting to hurt yourself or to end your life; withdrawing from friends and family; preoccupation with death and dying; giving away prized possessions; or any other unusual changes in behavior or mood. Be sure that your family or caregiver knows which symptoms may be serious so they can call the doctor if you are unable to seek treatment on your own.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature, away from light, excess heat, and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

What should I do in case of OVERDOSE?

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to methsuximide.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

AHFS® Consumer Medication Information. © Copyright, The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: May 1, 2009.