Vigabatrin

Generic name: Vigabatrin
Dosage form: oral tablet, powder for oral solution
Drug class: Gamma-aminobutyric acid analogs

Usage of Vigabatrin

Vigabatrin (Sabril, Vigadrone) is an antiepileptic or anticonvulsant drug used to treat epilepsy and infantile spasms.

Vigabatrin is thought to work by stabilizing the electrical activity in your brain and calming it. It does this by increasing the amount of an inhibitory neurotransmitter (chemical messenger) called GABA (gamma aminobutyric acid).

Vigabatrin helps to increase the amount of GABA in your central nervous system by blocking the action of an enzyme called GABA-T (GABA-transaminase), which helps to break down GABA when it is not needed.

Vigabatrin was first approved for marketing under the brand name Sabril by the US Food and Drug Administration (FDA) in 2009. Since then several generic versions of the drug have come to market, including one which is sold under the brand name Vigadrone.

Vigabatrin side effects

Vigabatrin can cause serious side effects, including:

See “Important information” above.

Sleepiness and tiredness. See “What should I avoid while taking vigabatrin?” above.

Vigabatrin may cause your baby to be sleepy. Sleepy babies may have a harder time suckling and feeding, or may be irritable.

Weight gain that happens without swelling.

The following serious side effects happen in adults. It is not known if these side effects also happen in babies who take vigabatrin.

low red blood cell counts (anemia).

nerve problems. Symptoms of a nerve problem can include numbness and tingling in your toes or feet. It is not known if nerve problems will go away after you stop taking this medication.

swelling.

If you or your child has complex partial seizures, vigabatrin may make certain types of seizures worse. Tell your healthcare provider right away if your (or your child's) seizures get worse.

The most common side effect of vigabatrin in adults include:

blurred vision,

sleepiness,

dizziness,

problems walking or feeling uncoordinated,

shaking (tremor), and

tiredness.

The most common side effect of vigabatrin in children 3 to 16 years of age is weight gain. Also expect side effects like those seen in adults.

If you are giving vigabatrin to your baby for infantile spasms:

Vigabatrin may make certain types of seizures worse. You should tell your baby’s healthcare provider right away if your baby’s seizures get worse. Tell your baby’s healthcare provider if you see any changes in your baby’s behavior.

The most common side effects of vigabatrin in babies include:

Sleepiness - this medication may cause your baby to be sleepy. Sleepy babies may have a harder time suckling and feeding or may be irritable.

Swelling in the bronchial tubes (bronchitis)

Ear infection

Irritability

Tell your healthcare provider if you or your child have any side effect that bothers you or that does not go away. These are not all the possible side effects of this medication.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Before taking Vigabatrin

Tell your healthcare provider if you are pregnant or plan to become pregnant. Vigabatrin can cause harm to your unborn baby. You and your healthcare provider will have to decide if you should take this medication while you are pregnant.

If you become pregnant while taking vigabatrin, talk to your healthcare provider about registering with the North American Antiepileptic Drug Pregnancy Registry. You can enroll in this registry by calling 1-888-233-2334. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/. The purpose of this registry is to collect information about the safety of antiepileptic medicine during pregnancy.

Tell your healthcare provider if you are breastfeeding or planning to breastfeed. Vigabatrin can pass into breast milk and may harm your baby. Talk to your healthcare provider about the best way to feed your baby if you take this medication.

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How to use Vigabatrin

The recommended dose of vigabatrin in patients with refractory complex partial seizures is:

Adults (17 years of age and older): Start at 1000 mg/day (500 mg twice daily). Increase total daily dose weekly in 500 mg/day increments, to the recommended dose of 3000 mg/day (1500 mg twice daily).

Pediatric patients (2 to 16 years of age): The recommended dosage is based on body weight and administered as two divided doses (see table below).

The dosage may be increased in weekly intervals, depending on response.

Dose patients weighing more than 60 kg according to adult recommendations. Body weight (kg) Total daily dose* Starting dose (mg/day)

Total daily dose* Maintenance dose# (mg/day)

10-15 kg 350 mg 1050 mg > 15-20 kg 450 mg 1300 mg > 20-25 kg 500 mg 1500 mg >25-60 kg 500 mg 2000 mg

* Administer in two divided doses # Maintenance dose based on 3000 mg/day adult-equivalent dose

The recommended dose of vigabatrin in patients with infantile spasms is:

Start at a daily dose of 50 mg/kg (25 mg/kg twice daily). Increase total daily dose every 3 days, in increments of 25 mg/kg/day to 50 mg/kg/day, up to a maximum daily dose of 150 mg/kg (75 mg/kg twice daily).

See full prescribing information for further information about vigabatrin dosing.

Warnings

Vigabatrin can cause serious side effects, including:

Permanent vision loss

Magnetic resonance imaging (MRI) changes in babies with infantile spasms

Risk of suicidal thoughts or actions

1. Permanent vision loss:

Vigabatrin can damage the vision of anyone who takes it. Some people can have severe loss particularly to their ability to see to the side when they look straight ahead (peripheral vision). With severe vision loss, you may only be able to see things straight in front of you (sometimes called “tunnel vision”). You may also have blurry vision. If this happens, it will not get better.

Vision loss and use of vigabatrin in adults and children 2 years and older: Because of the risk of vision loss, this medication is used to treat complex partial seizures only in people who do not respond well enough to several other medicines.

Tell your healthcare provider right away if you (or your child):

might not be seeing as well as before starting this medication.

start to trip, bump into things, or are more clumsy than usual.

are surprised by people or things coming in front of you that seem to come out of nowhere.

These changes can mean that you (or your child) have damage to your vision.

It is recommended that your healthcare provider test your (or your child’s) vision (including peripheral vision) and visual acuity (ability to read an eye chart) before you (or your child) start this medication or within 4 weeks after starting it, and at least every 3 months after that until it is stopped. It is also recommended that you (or your child) have a vision test about 3 to 6 months after vigabatrin is stopped. Your vision loss may get worse after you stop taking this medication.

Some people are not able to complete testing of vision. Your healthcare provider will determine if you (or your child) can be tested. If you (or your child) cannot complete vision testing, your healthcare provider may continue prescribing this medication, but your healthcare provider will not be able to watch for any vision loss you (or your child) may get.

Even if your vision (or your child’s vision) seems fine, it is important that you (or your child) get these regular vision tests because vision damage can happen before you (or your child) notice any changes.

These vision tests cannot prevent the vision damage that can happen with vigabatrin, but they do allow the healthcare provider to decide if you (or your child) should stop it if your vision has gotten worse.

Vision testing may not detect vision loss before it is severe.

If you do not have these vision tests regularly, your healthcare provider may stop prescribing this medication.

If you drive and your vision is damaged by vigabatrin, driving might be more dangerous, or you may not be able to drive safely at all. Talk about this with your healthcare provider.

Vision loss in babies: Because of the risk of vision loss, vigabatrin is used in babies 1 month to 2 years of age with infantile spasms only when you and your healthcare provider decide that the possible benefits of this medication are more important than the risks.

Parents or caregivers are not likely to recognize the symptoms of vision loss in babies until it is severe. Healthcare providers may not find vision loss in babies until it is severe.

It is difficult to test vision in babies, but, to the extent possible, all babies should have their vision tested before starting this medication or within 4 weeks after starting it, and every 3 months after that until it is stopped. Your baby should also have a vision test about 3 to 6 months after this medication is stopped.

Your baby may not be able to be tested. Your healthcare provider will determine if your baby can be tested. If your baby cannot be tested, your healthcare provider may continue prescribing vigabatrin, but your healthcare provider will not be able to watch for any vision loss.

Tell your healthcare provider right away if you think that your baby is:

not seeing as well as before taking this medication.

acting differently than normal.

Even if your baby’s vision seems fine, it is important to get regular vision tests because damage can happen before your baby acts differently. Even these regular vision exams may not show the damage to your baby’s vision before it is severe and permanent.

All people who take vigabatrin:

You are at risk for permanent vision loss with any amount of vigabatrin.

Your risk of vision loss may be higher the more of this medication you take daily and the longer you take it.

It is not possible for your healthcare provider to know when vision loss will happen. It could happen soon after starting treatment or any time during treatment. It may even happen after treatment has stopped.

Because vigabatrin might cause permanent vision loss, it is available to healthcare providers and patients only under a special program called the Vigabatrin Risk Evaluation and Mitigation Strategy (REMS) Program. This medication can only be prescribed to people who are enrolled in this program. As part of the Vigabatrin REMS Program, it is recommended that your healthcare provider test your (or your child’s) vision from time to time (periodically) while you (or your child) are being treated with this medication, and even after you (or your child) stop treatment. Your healthcare provider will explain the details of the Vigabatrin REMS Program to you. For more information, go to www.vigabatrinREMS.com or call 1-866-244-8175.

2. Magnetic resonance imaging (MRI) changes in babies with infantile spasms:

Brain pictures taken by magnetic resonance imaging (MRI) show changes in some babies after they are given vigabatrin. It is not known if these changes are harmful.

3. Risk of suicidal thoughts or actions:

Like other antiepileptic drugs, vigabatrin may cause suicidal thoughts or actions in a very small number of people, about 1 in 500 people taking it. Call a healthcare provider right away if you or your child have any of these symptoms, especially if they are new, worse, or worry you:

thoughts about suicide or dying

attempts to commit suicide

new or worse depression

new or worse anxiety

feeling agitated or restless

panic attacks

trouble sleeping (insomnia)

new or worse irritability

acting aggressive, being angry, or violent

acting on dangerous impulses

an extreme increase in activity and talking (mania)

other unusual changes in behavior or mood

Suicidal thoughts or actions can be caused by things other than medicines. If you or your child have suicidal thoughts or actions, your healthcare provider may check for other causes.

How can I watch for early symptoms of suicidal thoughts and actions?

Pay attention to any changes, especially sudden changes, in mood, behaviors, thoughts, or feelings.

Keep all follow-up visits with your healthcare provider as scheduled.

Call your healthcare provider between visits as needed, especially if you are worried about symptoms.

Do not stop this medication without first talking to a healthcare provider.

Stopping this medication suddenly can cause serious problems. Stopping a seizure medicine suddenly can cause seizures that will not stop (status epilepticus) in people who are being treated for seizures.

What other drugs will affect Vigabatrin

Tell your healthcare provider about all the medicines you or your child take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Vigabatrin and other medicines may affect each other causing side effects.

Especially tell your healthcare provider if you take phenytoin. Your dose of phenytoin may need to be adjusted.

Taking vigabartin with clonazepam, may increase your chances of experiencing clonazepam-associated adverse reactions.

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