In the U.S.—

• Anticonvulsant

Zonisamide ( zoh-NIS-a-mide) is used to control some kinds of seizures in the treatment of epilepsy.

This medicine is available only with your doctor's prescription, in the following dosage form:

Oral
• Capsules (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For zonisamide, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to zonisamide, or to sulfonamide antibiotics (for example, Bactrim® or Septra®). Also tell your doctor and pharmacist if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Zonisamide has not been studied in pregnant women. However, studies in animals have shown that zonisamide causes birth defects and other serious problems with the pregnancy. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—Zonisamide has been shown to pass into breast milk. However, it is not known whether this medicine causes problems in nursing babies. Mothers who are taking zonisamide and who wish to breast-feed should discuss this with their doctor.

Children— Safety and efficacy have not been established in children who are under 16 years of age and is not approved for use.Studies in children have shown that some children are at higher risk for oligohidrosis (decreased sweating) and hyperthermia (unusually high body temperature), especially in warm or hot weather. This can sometimes result in heat stroke and hospitalization.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of zonisamide in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking zonisamide, it is especially important that your doctor and pharmacist know if you are taking any of the following:

• Alcohol or
• Carbamazepine [e.g. Tegretol]) or
• Phenobarbital [e.g. Barbita or Mysoline] or
• Phenytoin [e.g. Dilantin] or
• Valproate [e.g. Depakote]—Taking any of these medicines with zonisamide may decrease the amount of zonisamide in the blood, causing an decrease in effectiveness, and a possible increase in seizure frequency

• Anticholinergics (medicine for abdominal or stomach spasms or cramps or drying up a runny nose) or
• Acetazolamide [e.g., Diamox] or
• Dichlorphenamide [e.g., Daranide] or
• Methazolamide [e.g., Neptazane]—Side effects of zonisamide, such as dryness of mouth or heat intolerance, may be more likely to occur

• Central nervous system depressants (medicines that cause drowsiness)—Using these medicines or alcohol with zonisamide may cause increased drowsiness

• Kidney disease or

• Liver disease

Take this medicine only as directed by your doctor to help your condition as much as possible. Do not take more or less of it, and do not take it more or less often than your doctor ordered.

Zonisamide may be taken with or without food, on a full or empty stomach. Swallow capsule whole. Do not break or crush.

Dosing—

The dose of zonisamide will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of zonisamide. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking zonisamide

• For oral dosage form (capsules):
  • For partial seizures (epilepsy)
    • Adults and teenagers 16 years of age and older—At first, 100 milligrams (mg) a day for two weeks. The dose may then be increased by 100 mg a day once every two weeks, as decided by your doctor. However, the dose is usually not more than 400 mg a day, taken one or two times a day.
    • Children up to 16 years of age—Use and dose must be determined by the doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Ask your health care professional how you should dispose of any medicine you do not use. Be sure that any discarded medicine is out of the reach of children.

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly, and to check for unwanted effects.

If your condition does not improve within a few weeks or if it becomes worse, check with your doctor.

This medicine may cause some people to become drowsy, dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; prescription pain medicines, or sleep medicines. Do not take other medicines unless they have been discussed with your doctor. This especially includes nonprescription medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems.

Contact your doctor immediately if you develop skin rash, experience fever, sore throat, oral ulcers, easy bruising, or worsening of seizures.

These medicines may make you sweat less, causing your body temperature to increase. Use extra care not to become overheated during exercise or hot weather while you are taking this medicine, since overheating may result in heat stroke. Also, hot baths or saunas may make you dizzy or faint while you are taking this medicine.

Use effective birth control methods to prevent pregnancy if you are sexually active and able to become pregnant.

Do not stop taking zonisamide without first checking with your doctor. Stopping the medicine suddenly may cause your seizures to return or to occur more often. Your doctor may want you to gradually reduce the amount you are taking before stopping completely.

It is important that you drink plenty of fluids every day during therapy with zonisamide to help prevent kidney stones from forming.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

• Symptoms of overdose

  Get emergency help immediately if any of the following symptoms of overdose occur

  • Confusion;  difficult or labored breathing ;  faintness;  loss of consciousness ;  slow or irregular heartbeat 
  
  

Check with your doctor immediately if any of the following side effects occur:

• More common
  • Discouragement;  feeling sad or empty ;  irritability;  lack of appetite;  loss of interest or pleasure;  mood or mental changes;  shakiness or unsteady walking 
  
  

• tiredness;  trouble concentrating;  trouble sleeping  

• Less common
  • Agitation;  bruising;  delusions;  hallucinations;  large, flat blue or purplish patches on the skin;  rash 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome.

• More common
  • Abdominal pain;  anxiety;  difficulty with memory;  dizziness;  double vision;  headache;  loss of appetite;  nausea;  restlessness;  sleepiness;  sleeplessness;  unusual drowsiness;  unusual tiredness or weakness 
  
  

• Less common
  • Aching muscles or joints;  acid or sour stomach;  bad, unusual, or unpleasant taste in mouth ;  belching;  change in taste ;  chills;  constipation;  diarrhea;  difficulty in speaking;  difficulty in thinking;  dry mouth;  fever;  general ill feeling;  headache;  heartburn;  indigestion;  mental slowness;  nervousness;  runny or stuffy nose;  sneezing;  tingling, burning, or prickly feelings on skin;  uncontrolled, back and forth, or rolling eye movements;  weight loss 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.