In Canada—

• Anticonvulsant

Vigabatrin ( VYE–gab–a–trin) increases the amount of the brain chemical GABA. It is thought that epileptic seizures are the result of low levels of GABA. By increasing the amount of GABA, vigabatrin reduces the likelihood of an epileptic seizure.

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

Oral
• Powder (Canada)
• Tablets (Canada)

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

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to vigabatrin. Also tell your health care provider if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy— Studies have not been done in pregnant women. However, studies in rabbits have shown that vigabatrin causes birth defects. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding— It is not known if vigabatrin passes into breast milk. Because of the risk of unwanted effects in the nursing infant, breast-feeding is not recommended.

Children—This medicine has been tested in children and, in effective doses, has not been shown to cause different problems than it does in adults.

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 or if they cause different side effects or problems in older people. There is no specific information comparing use of vigabatrin in the elderly with use in other age groups.

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. Tell your health care professional if you are using any other prescription or nonprescription (over-the-counter [OTC]) medicine.

• Mental illness—Patients with a history of emotional or behavioral disturbances may be more likely to have an episode following vigabatrin therapy.

• Kidney disease—Vigabatrin is removed from the body by the kidney; slower removal from the body may increase the chance of side effects

Dosing—

The dose of vigabatrin 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 vigabatrin. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form ( powder):
  • For epilepsy
    • Adults— To start, 1000 milligrams (mg) a day. The doctor may need to adjust the dose depending on your response to the medicine. However, the dose is usually not more than 4000 mg a day.
    • Children—The dose is based on body weight and will be determined by your doctor. To start, 40 milligrams (mg) per kilogram (kg) (18.2 mg per pound) of body weight per day. Your doctor may increase your dose as needed. However, the dose is usually not more than 100 mg per kg (45.5 mg per pound) of body weight a day, taken in two smaller doses.
  • For infantile spasms
    • Children—The dose is based on body weight and will be determined by your doctor. The usual dose is 50 to 100 mg per kg (22.7 to 45.5 mg per pound) of body weight per day, given in smaller doses twice a day. The doctor may need to adjust the dose based on your response to the medicine.
• For oral dosage form (tablets):
  • For epilepsy
    • Adults—To start, 1000 milligrams (mg) a day. The doctor may need to adjust the dose depending on your response to the medicine. However, the dose is usually not more than 4000 mg a day.
    • Children—The dose is based on body weight and will be determined by your doctor. To start, 40 mg per kg (18.2 mg per pound) of body weight a day. Your doctor may increase your dose as needed. However, the dose is usually not more than 100 mg per kg (45.5 mg per pound) of body weight a day, taken in two smaller doses.

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.
• Store away from heat and direct light.
• 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 important that you visit your physician .

If you will be taking this medicine for a long time, it is very important that your eye doctor check you approximately every 3 months for any visual problems.

If your symptoms do not improve or if they become worse, check with your doctor.

Do not take other medicines unless they have been discussed 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, drowsy, or not alert, .

Do not suddenly stop taking this medicine without first checking with your doctor. Your doctor may want to reduce your dose gradually. Stopping this medicine suddenly may cause seizures.

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.

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

• More common

• Amnesia;  blurred vision ;  blue-yellow color blindness;  decreased vision or other vision changes;  eye pain ;  increase in seizures 

• Less common or rare
  • Uncontrolled rolling eye movements 
  
  

• Symptoms of overdose

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

  • Mood or mental changes 
  
  

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;  abnormal coordination ;  agitation;  anxiety;  clumsiness;  confusion;  constipation;  mental depression;  diarrhea;  dizziness;  drowsiness;  double vision or seeing double;  fatigue;  hyperactivity ;  increased movement;  joint pain;  burning, tingling, or prickly sensations ;  shakiness;  sleepiness or unusual drowsiness;  trembling;  tremor;  unsteadiness 
  
  

• Less common
  • Aggression;  concentration impaired;  headache;  increased saliva;  insomnia;  muscle weakness;  nausea;  speech disorder;  thinking abnormal;  vomiting;  weight gain 
  
  

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