Vigabatrin

(Date of issue: June 2015. Version: 1)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by Public Health England on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What is it?

Vigabatrin (Sabril®) is used to treat epilepsy, usually in combination with other epilepsy medicines.

Is it safe to take vigabatrin in pregnancy?

There is no yes or no answer to this question. When deciding whether or not to take vigabatrin during pregnancy it is important to weigh up how necessary vigabatrin is to your health against the possible risks to you or your baby, some of which will depend on how many weeks pregnant you are. Remaining well is particularly important during pregnancy and whilst caring for a baby. It is vital that epilepsy is well-controlled during pregnancy as seizures can harm both the mother and unborn child. For some pregnant women treatment with vigabatrin may be necessary.

This leaflet summarises the available scientific information relating to the effects of vigabatrin on a baby in the womb. It is advisable to consider this information if you are taking vigabatrin and are pregnant or could become pregnant in the future.

Your doctor is the best person to help you decide what is right for you and your baby.

What if I have already taken vigabatrin during pregnancy?

Vigabatrin is usually taken in combination with other epilepsy medicines. If you are pregnant you should let your doctor know as soon as possible so that your epilepsy medication can be reviewed to ensure you are on the most suitable medicine(s) and are taking the appropriate dose. Because of the normal bodily changes that occur as pregnancy progresses, your doctor may advise closer monitoring of your health to assess whether the dose of your epilepsy medicine(s) needs to be adjusted during your pregnancy for it to remain effective.

It is very important that you do not stop or alter the dose of any medicine you are taking without first speaking to your doctor. If you are already pregnant, making changes to your medicine yourself may be more harmful to both you and your baby than continuing to take that medicine.

Why has my doctor recommended that I take high dose folic acid?

Some epilepsy medicines can cause low folic acid levels. Folic acid is necessary for a baby’s growth and development in the womb. Women who have low folic acid levels in early pregnancy are much more likely to have a baby with a birth defect of the spine called a neural tube defect. It is therefore recommended in the UK that all women taking vigabatrin also take high dose folic acid (5mg/day) instead of the standard dose of 400 micrograms whilst trying to conceive and during the first trimester of pregnancy. High dose folic acid has to be prescribed by a doctor.

Although it is very clear that taking folic acid in pregnancy protects against neural tube defects in general, there is not yet any scientific evidence to show that taking folic acid supplements at either high or standard doses can protect against any of the birth defects or other problems that may be specifically caused by epilepsy medicines. However, until more scientific information is available, high dose folic acid is advised. For more information please see the folic acid bumps leaflet.

Can taking vigabatrin in pregnancy cause birth defects in the baby?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

It is currently unclear whether vigabatrin use in pregnancy can cause birth defects in the baby. Soon after vigabatrin was first available the manufacturer received a number of reports of birth defects in a few babies whose mothers took vigabatrin in pregnancy. However, the babies did not appear to have similar types of birth defects (which would be expected if they were caused by the same medicine). Two subsequent small scientific studies involving a total of 23 pregnant women taking vigabatrin, mostly in combination with other anti-epileptic medicines, did not find any evidence of an increased risk of birth defects in babies exposed to vigabatrin in the womb.

Vigabatrin use in adults can cause long-term problems with eyesight. There is therefore a possible (theoretical) risk that exposure to vigabatrin in the womb could affect the baby’s eyesight. There is one isolated report of eyesight problems in a baby whose mother took vigabatrin in pregnancy. However, since then reports describe six babies who were specifically tested for eyesight problems and were found to be normal. 

Many more large scientific studies of pregnant women taking vigabatrin need to be carried out before we can say whether or not vigabatrin increases the risk of birth defects or problems with eyesight in the baby. Because most women on vigabatrin will also be taking other epilepsy medicines, future research will ideally address which combinations of vigabatrin and other epilepsy medicines are safest for the unborn child.

Can taking vigabatrin in pregnancy cause miscarriage, stillbirth, preterm birth or my baby to be small at birth (low birth weight)?

It is currently unclear whether use of vigabatrin in pregnancy may increase the risk of miscarriage, stillbirth, preterm birth, or low birth weight in the baby because to date, no studies have addressed these risks. These pregnancy outcomes need to be considered in future research.

Can taking vigabatrin in pregnancy cause other health problems in the child?

Withdrawal symptoms at birth (neonatal withdrawal)
Withdrawal symptoms are thought to occur when a newborn baby’s body has to adapt to no longer getting certain types of medicines through the placenta.

Vigabatrin works in a similar way to other medicines that are known to cause neonatal withdrawal. There is an isolated report of neonatal withdrawal in a baby who was exposed to vigabatrin in combination with another epilepsy medicine (carbamazepine) in the womb. Close monitoring of your baby for a few days after birth may therefore be advised if you have taken vigabatrin regularly in the weeks before delivery. Monitoring of your baby may be particularly important if you have taken vigabatrin in combination with other anti-epileptic medicines or medicines that act on the brain.

Learning and behavioural problems
A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour. Because vigabatrin acts upon the brain there have been concerns that its use in pregnancy may affect a baby’s brain development. Other epilepsy medicines, particularly sodium valproate, are known to cause lifelong alterations to learning and behaviour in some children exposed in the womb.

It is currently unclear whether vigabatrin exposure in the womb causes alterations to learning and behaviour, as no studies have been carried out to investigate this. Because vigabatrin is generally taken in combination with other epilepsy medicines, future studies should ideally address the effects of specific combinations of vigabatrin and other epilepsy medicines. 

Will my baby need extra monitoring?

As part of their routine antenatal care most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and to check the baby’s growth. Women with epilepsy are likely to be more closely monitored during pregnancy to ensure that they remain well throughout and that their baby is growing and developing as expected. 

Because the effects of vigabatrin on a developing pregnancy are unknown, your doctor may wish to monitor you more closely and may offer you the option of having more detailed anomaly scans around 12 weeks of pregnancy. It is, however, harder to see birth defects when the baby is still so small, which is why the main scan for birth defects is generally offered at around 20 weeks of pregnancy. It is important to understand that scans are not able to pick up all birth defects and cannot predict whether a baby will have problems with learning and behaviour.

If you have taken vigabatrin around the time of delivery your baby may require extra monitoring after birth because of the possible risk of neonatal withdrawal.

Are there any risks to my baby if the father has taken vigabatrin?

We would not expect any increased risk to your baby if the father took vigabatrin before or around the time you became pregnant.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org.  

General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

   

www.medicinesinpregnancy.org

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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