Vigabatrin

How to Take:

Follow the directions of your prescribing provider and call if you have any questions. How much and when to take the medicine may vary for each person. 

In adults, usually, the drug is started by taking 500 mg twice a day (1000 mg/day). The dose may be increased at weekly intervals by 500 mg per day to a final daily dose of 1500 mg twice a day (3000 mg daily), based on how well it works and how well you tolerate it.

In children, dosing usually starts at 50 mg per kg each day. The dose may be increased by 25 to 50 mg per kg each week to a maximum dose of 150 mg per kg each day. For example, in children from 10 to 16 years old, the recommended dose starts at 250 mg twice a day. Increase as directed by the prescribing provider to a 1000 mg twice a day. 

Children who weigh more than 60 kg are usually given doses similar to adult recommendations. 

Your provider may suggest starting the medication at a different rate, either faster or slower. Or the daily dose may be different, depending on individual circumstances.  

Sabril is well-absorbed. You can take it with or without food, but it's a good idea to be consistent about how you take it.

Be sure to use only the amount that the provider prescribes. If you think you've used one or two extra tablets, call your doctor for advice.

If an overdose of the medicine has been taken, call your local poison control center or emergency room right away, unless you have special instructions from the doctor.

Don't stop taking Sabril or change the amount you use without talking to the prescribing provider first. Stopping any seizure medicine all at once can cause a serious problem called status epilepticus.

If you have kidney (renal) disease, the dose of Sabril should be adjusted.

For people with mild kidney problems the dose should be decreased by 25%, for people with moderate renal impairment, the dose should be decreased by 50%; and for people with severe renal impairment, the dose should be decreased by 75%.

Use of Powder:

Empty contents of the package into a clean cup. 

Mix the powder with 10 ml or 2 teaspoons of water. Use cold or room temperature water. 

Use the syringe that comes with the powder to draw up the medicine and put it in the child's mouth. 

Prepare and give each dose of medicine immediately. Don't save any unused medicine for a later time. 

How to Store:

All forms of Sabril should be stored at room temperature, away from light and moisture.

 The manufacturer recommends storing Sabril at 20° to 25°C (68° to 77°F), so if you live in a hot climate try to keep it in a cool place. You may take it with you when traveling in temperatures between 15° to 30°C (59° to 86°F). The drug may be stable in colder or hotter temperatures, but information is lacking.

Keep all medicines out of the reach of children.

-If you forget a dose, take it as soon as you remember. If it is almost time for the next dose, delay that dose for a few hours instead of taking two doses very close together. Then go back to the regular schedule.

-Do your best to follow the prescribing provider's directions. If you forget doses often, get a special pillbox and use an alarm on a watch or cellphone to remind you when to take a dose.  

-Make sure to write down any missed doses and share this with your doctor.

-Taking the right amount of seizure medicine on time every day is the most important step in preventing seizures!

Brain cells need to work (fire) at a certain rate to function normally. During a seizure, brain cells are forced to work much more rapidly than normal. Sabril makes chemical changes in the brain that slow down brain cell firing during a seizure.

-After taking Sabril tablets, peak blood levels are reached in 1-2.5 hours and effects probably last several days.

-Sabril is usually taken two times a day to lessen side effects from a large single dose.

-People with poor kidney function usually need to take less Sabril and may take it less often, because it stays in their body longer.

Sabil was approved in the US based on two studies for complex partial seizures and two for infantile spasms. All of the studies showed more improvement in seizures in the group of patients taking Sabil compared to a placebo sugar pill. But Sabril only reduced seizures, and did not eliminate them or cure the underlying epilepsy.

Sabril can have serious side effects, and so it should only be used after other medicines have been tried, and after careful consideration of possible benefits versus the risks.

Vision 

-The side effect of greatest concern is a potential for loss of peripheral vision. This means that people may not see well to the sides or high up and low down. According to the manufacturer, the risk increases with total dose and how long it is used. There is no amount of Sabril that is known to be free of the risk for potential vision loss.  

-Vision loss may occur in up to 30% of people taking Sabril. Risk of new and worsening vision loss continues as long as Sabril is used, and possibly after stopping the drug. Periodic vision testing (recommended to be every 3 months) is required for patients on Sabril, but cannot reliably prevent vision damage.

Changes in brain myelin

-Vigabatrin occasionally can produce changes in brain myelin, which is the coating of nerve cells. These changes can be seen with a brain MRI, but their clinical significance is unknown. The most common disease of myelin is multiple sclerosis, but there is no evidence that vigabatrin produces multiple sclerosis. MRI changes usually resolve with discontinuation of vigabatrin.

Changes in mood, behavior, suicidal thinking

All seizure medicines, including Sabril, carry warnings about suicidal thinking and tendencies. In a pooled analysis of 11 studies, the FDA noted 4 suicides among 27,863 patients. Epilepsy itself is associated with a higher risk for depression and suicide. You and your family should be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to your healthcare providers.

Other side effects

This table shows potential side effects that occurred in people taking Sabril when compared to people taking a placebo or inactive drug. 

Side Effect	Sabril	Placebo
Fatigue	27%	16%
Sleepiness	22%	13%
Dizziness	21%	17%
Tremor	14%	8%
Nasopharyngitis	13%	10%
Blurry vision	11%	5%
Memory impairment	10%	3%
Stomach upset, constipation or diarrhea	10%	8%
Upper respiratory tract infection	9%	5%
Coordination abnormal	9%	2%
Weight gain	8%	3%
Joint pains	8%	3%
Urinary tract infection	4%	0%
Headache	4%	1%
Fluid retention	2%	1%

Many other side effects were seen, but it is not known whether they were caused by Sabril, other medicines or non-drug reasons.

Laboratory abnormalities

Anemia (low red blood counts) were seen in 6% of patients taking Sabril vs. 2% of those on placebo. Sabril decreases liver enzyme markers AST and ALT. While not a sign of a problem, the decrease could make it harder to detect other problems.

Vision:

Vigabatrin has serious potential adverse effects and carries an FDA black box warning about the potential for causing loss of peripheral vision. This means that the drug may cause permanent, changes in visual fields that may range from mild to severe.

- The terms used to describe the visual field problem are bilateral concentric visual field constriction that can occur in 30% or more of patients taking the medication. This vision problem can also include 'tunnel vision' to within 10 degrees of visual fixation which can be disabling. 

-In some cases, vigabatrin may damage the central retina of the eye and decrease visual acuity.

-The onset of visual loss is unpredictable. It can occur anytime during treatment with vigabatrin, for example within weeks of starting it, sooner, or even after months or years.

-The risk of visual loss increases with increasing doses and cumulative exposure (for example at higher doses or longer periods of time the drug is used).  There is no dose or length of time on the drug known to be free of risk of visual loss.

-It is recommended that adults using Sabril have a formal opthalmologic or eye exam within the first 4 weeks of starting treatment and every 3 months during therapy.  Visual or eye assessments should also be done about 3 to 6 months after the therapy is stopped.  Some patients may be exempted from these ophthalmologic (eye) exams. Side effects related to vision change or loss should be reported to the Sabril REMS Program at 1-888-457-4273.

-Once detected, visual loss is irreversible. It is expected that even with frequent monitoring, some patients could develop severe visual loss. It is possible that visual loss could worsen despite stopping the drug.

-Because of this risk of permanent visual loss, the drug is available only through select specialty and inpatient pharmacies.  Health care providers prescribing Sabril must complete an enrollment form and be certified with the Sabril REMS Program. 

-Because of the risk for visual problems and because vigabatrin, when it is effective, provides an observable symptomatic benefit, a patient who does not show substantial benefit within 3 months of starting treatment should be taken off the drug. If, in the clinical judgment of the prescriber, evidence of treatment failure becomes obvious earlier than 3 months, treatment should be stopped at that time. Patient response to and continued need for treatment should be periodically assessed. This is true for both children and adults.

-The diagnostic approach to assess and monitor vision has been outlined by the pharmaceutical company. Perimetry is recommended, preferably by automated threshold visual field testing. Additional testing may also include electroretinography, retinal imaging, and other methods, depending on the physician’s choice. In patients exempted from visual testing, the treatment may continue according to clinical judgment with appropriate patient counseling.

Other side effects

-Somnolence (sleepiness) and fatigue, symptoms of peripheral neuropathy, edema and weigt gain. The average weight gained is 3.5 kilograms and this has been reported in 17% of patients.

People whose vision cannot be monitored should not take Sabril. People known to be allergic to Sabril should not take it.

See package insert.

-Any time a doctor suggests a new prescription, be sure to talk about what other medicines, supplements, herbs, and vitamins are already being taken. Sometimes one kind of medicine changes the way another kind of medicine works in the body. If two kinds of medicine affect each other, the doctor may prescribe something else or change the amount to be taken.

-In clinical trials, Sabril lowered phenytoin (Dilantin) levels about 20%, but had little or no effect on other antiseizure drug levels.

-Other antiseizure drugs have little effect on Sabril.

-The manufacturer’s package insert says that Sabril is unlikely to affect steroid oral contraceptives or hormonal birth control. 

Sabril has been tested in children and can be used in children with refractory complex partial seizures and infantile spasms. Side effects (discussed elsewhere) can be severe, so Sabril should only be used in children with careful consideration of the possible risks versus benefits.

The U.S. Food and Drug Administration (FDA) lists Sabril in Pregnancy Category C, known to cause birth defects in animals, and suspected to be able to produce birth defects in people. Talk to your doctor or another health professional if you are pregnant or plan to become pregnant. We don't yet have enough information to be able to estimate the risk of various types of birth defects that might occur if Sabril is taken during pregnancy. We also don't know enough to compare the risk with Sabril to the risk with other seizure medicines. The risk of birth defects is generally higher for women who take more than one AED and for women with a family history of birth defects.

Women who are capable of becoming pregnant should take at least 400 micrograms (0.4 mg) of folic acid (folate) daily to help prevent a type of birth defect called a neural tube defect. (The best-known of these is spina bifida, in which the spinal cord is not completely enclosed.) Women at high risk, such as those with a history of this kind of defect in a previous pregnancy, should take 4000 mcg (4 mg) daily, beginning before they become pregnant. Pregnant patients taking SABRIL are encouraged to call the North American Antiepileptic Drug (NAAED) Pregnancy Registry at 1-888-233-2334, or visit online at www.aedpregnancyregistry.org.

Sabril is excreted in breast milk and could cause toxicity in the baby. If you want to breast-feed your baby, check with your doctor about what seizure medicine would be best for you. Women who are capable of becoming pregnant should take at least 400 micrograms (0.4 mg) of folic acid (folate) daily to help prevent a type of birth defect called a neural tube defect. (The best-known of these is spina bifida, in which the spinal cord is not completely enclosed.) Women at high risk, such as those with a history of this kind of defect in a previous pregnancy, should take 4000 mcg (4 mg) daily, beginning before they become pregnant.

Studies of elderly patients taking Sabril are few, but seniors are prone to have more confusion, sedation and side effects because their kidneys do not clear the drug as well as in younger patients.

For adults, Sabril is usually started at 500 milligrams (mg) twice daily. The dosage can be increased to 1000 mg twice a day after two weeks, then 1500 mg twice a day two weeks later. Dosage usually would be continued at 1500 mg twice a day (3000 mg per day total). For people who are particularly prone to medication side effects, the initiation may start more slowly. On the other hand, some patients with an urgent need to control seizures quickly might increase dosage faster than usual. You should plan the medication schedule with your doctor.

"In the United States, companies that manufacture medicines are required to publish certain kinds of information about each product. This document is commonly known as a “package insert” because it is usually included with each package of the medicine. You can also read these documents (also called ""prescribing information"") online. The U.S. package insert for Sabril is found at:

• http://www.lundbeck.com/upload/us/files/pdf/Products/Sabril_PI_US_EN.pdf

To learn how to read and understand a package insert, see "How to read a package insert"