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TREATMENTS FOR EPILEPSY


Drugs known as anticonvulsants

DRUG;- VIGABATRIN

Drugs available Brand name(s)

Forms available

Tablets

Capsules

Liquid

Injection

Vigabatrin Sabril

 


(Sachets)

 

What is vigabatrin used for ?

Vigabatrin is most often used in the treatment of epilepsy, to help control fits or blackouts. It is usually used with other antiepileptic drugs. There are many other anticonvulsant drugs. It may be necessary to try several drugs in different doses or combinations to find the best therapy for you i.e. least side effects and maximum effect.

How does vigabatrin work ?

Epileptic seizures (fits or blackouts) happen when an abnormal electrical discharge, like a short circuit causing a spark, occurs in the brain. There are many naturally occurring chemical messengers (or "neurotransmitter") in the brain. One is called GABA and is "inhibitory" on the brain and another one is called glutamate, which "excites" the brain.

Once GABA has worked, there are other chemicals (or enzymes) in the brain which are there to break GABA down so that it can no longer work. In people with normal levels of GABA this prevents there being too much. In some people it is thought that there may not be enough GABA in the brain and that this helps to "trigger" fits. Vigabatrin helps to stop the breakdown of GABA and so leaves enough of this chemical to calm the brain and to help prevent the fits and blackouts.

How should I take it ?

The tablets should be swallowed with at least half a glass of water whilst sitting or standing, so that they reach the stomach and do not stick in the throat. Vigabatrin sachets should be opened and the contents sprinkled into a glass of water, stirred with a spoon and swallowed as soon as the fizzing stops.

When should I take it ?

Take it as directed on the medicine label. It is particularly important to take the drugs regularly each day as directed by your doctor to make sure that you are getting the best control of your illness from your medicine.

How long will vigabatrin take to work ?

Vigabatrin should start to work soon after you start taking it. It may, however, take some time for your doctor to get the right dose for you. The aim is for the amount of medicine in your blood to be high enough to prevent or reduce fits, but low enough to give you the least amount of side-effects. Do not attempt to make any changes yourself.

How long will I need to keep taking vigabatrin for ?

Vigabatrin is a "preventative medicine" and so will usually need to be taken for a long time. It is important that you keep taking this medication until your doctor tells you to stop. Do not stop taking it just because you feel better. If you stop them before you are advised to do so your condition may well get worse.

Is vigabatrin addictive ?

Vigabatrin is not thought to be habit forming. For further discussion, click here.

Can I stop taking vigabatrin suddenly ?

You should never stop taking this medication suddenly or without advice from your doctor as this might mean an increase in fits or blackouts. Vigabatrin will nearly always need to be withdrawn slowly. If your doctor decides that you no longer require this drug it will be withdrawn gradually (like any treatment for epilepsy) to make sure that your fits do not return. This will usually be by a slight reduction in your dose every few weeks. You should therefore not experience any problems.

What should I do if I forget to take a dose ?

Start again as soon as you remember unless it is almost time for your next dose, then go on as before. Do not try to catch up by taking two or more doses at once as you may get more side-effects. You should tell your doctor about this next time you meet. If you are ill and vomit your tablets you should take that dose again. Missing a dose can cause your fits to return. The amount in your bloodstream may drop below the level needed to control your fits.

If you have problems remembering your doses (as very many people do) ask you pharmacist, doctor or nurse about this. There are some special packs, boxes and devices which can be used to help you remember.

What sort of side-effects might occur ?

Side effect What happens What to do about it
COMMON
Drowsiness You feel sleepy or sluggish the next morning. This should wear off after a few weeks. Don't drive or use machinery. If it does not, discuss with your doctor – it may be possible to adjust the dose.
Tiredness Feeling sleepy in the day. Discuss with your doctor. You may need to take it at a different time.
Headache Your head is pounding and painful. Try aspirin or paracetamol. Your pharmacist will be able to advise if these are safe to take with any other drugs you may be taking.
Low mood Feeling depressed and lacking interest in things Discuss with your doctor when you next see him or her. He or she may want to adjust your drug or dose.
UNCOMMON
Confusion Your mind is all mixed up or confused. Discuss with your doctor when you next see him or her. He or she may want to adjust your drug or dose.
Aggression Feeling excitable. You may be talkative, unfriendly or disinhibited. Discuss this with your doctor. He or she may want to adjust your drug or dose.
Weight gain A bigger appetite and putting on weight. A diet full of vegetables and fibre may help prevent weight gain. See also a separate question in this section.
Stomach upset This includes feeling and being sick and getting diarrhoea. If it's mild, see your pharmacist. If it lasts for more than a week or so, see your doctor
RARE
Sight changes - visual field defects, photophobia, retinal disorders Changes in your eyesight e.g. bright light being painful, loss of the edge of how wide you can see, problems with the retina It is now recommended to have your eyes tested by an ophthalmologist before starting vigabatrin, then regularly after that. If you lose any part of your sight, see a doctor urgently. Report any new symptoms and discuss this with your doctor. He or she may want to adjust your drug or dose.
Poor memory Difficulty remembering things Discuss this with your doctor. He or she may want to adjust your drug or dose.

Table adapted from UK Psychiatric Pharmacy Group leaflets, with kind permission (www.ukppg.org.uk )

Do not be worried by this list of side effects. You may get none at all. There are other rare side-effects. If you develop any unusual symptoms ask your doctor about them next time you meet.

Will vigabatrin make me drowsy ?

You may feel a little sleepy and so you must take care if you are allowed to drive or when operating any type of machinery. This effect should wear off or at least reduce after you have been taking them for a while.

Will vigabatrin cause me to put on weight ?

Many people put on some weight when they start vigabatrin but this is only a real problem in about one in twenty people. If, however, you do start to have problems with your weight tell your doctor next time you meet as he or she can arrange for you to see a dietician for advice.

Will it affect my sex life?

Drugs can affect desire (libido), arousal (erection) and orgasmic ability. Vigabatrin is not thought to have a significant affect on any of these.

Can I drink alcohol while I am taking vigabatrin ?

You should avoid alcohol while taking vigabatrin as it may make you feel more sleepy. This is particularly important if you are allowed to drive or operate machinery and you must seek advice on this.

Are there any foods or drinks that I should avoid ?

You should have no problems with any food or drink other than alcohol (see above).

Will vigabatrin affect my other medication ?

Tell your doctor of any medicines that you may be taking and also before starting or stopping any other drugs. There are very few problems although vigabatrin may reduce the effectiveness of phenytoin ("Epanutin"). This does not necessarily mean the drugs can not be used together, just that you may need to follow your doctors instructions very carefully.

You should also consult your pharmacist before buying any medicines over the counter.

If I am taking a contraceptive pill, will this be affected ?

There should be no problems with vigabatrin.

What if I want to start a family or discover I'm pregnant?

It is important to consider that there will be a risk to you and your child from taking a medicine during pregnancy but also a possible risk from stopping the medicine e.g. getting ill again. Unfortunately, no decision is risk-free. It will be for you to decide which is the least risk. All we can do here is to help you understand some of the issues, so you can make an informed decision. For your information, major malformations occur "spontaneously" in about 2-4% of all pregnancies, even if no drugs are taken. The main problem with medicines is termed "teratogenicity" i.e. a medicine causing a malformation in the unborn child. A medicine causing teratogenicity is called a "teratogen". Since a baby has completed it's main development between days 17 and 60 of the pregnancy (the so-called "first trimester") these first 2-16 weeks are the main concern. After that, there may be other problems e.g. some medicines may cause slower growth. The infant may also be affected after birth e.g. withdrawal effects are possible with some drugs.

If possible, the best option is to plan in advance. If you think you could become pregnant, discuss this with your doctor and it may be possible to switch to medicines thought to carry least risk, and take other risk-reducing steps e.g. adjusting doses, taking vitamin supplements etc. If you have just discovered you are pregnant, don't panic, but seek advice from your GP within the next few days if possible. He or she may also want to refer you on to someone with more specialist knowledge of your medicine.

Very few medicines have been shown to be completely safe in pregnancy and so no manufacturer or advisor can ever say any medicine is safe. They will usually advise not to take a medicine during pregnancy, unless the benefit is much greater than the risk. In the UK, there is the NTIS (National Teratology Information Service) who offer individual risk assessments. However, their advice should always be used to help you and your doctor decide what is the risk to you and your baby. There is a risk from taking the medicine and a risk should you stop a medicine e.g. you might become ill again and need to go back on the medication again. The advice offered here is just that i.e. advice, but may give you some idea about the possible risks and what (at the time of writing) is known through the medical press.

It may be helpful to know that in the USA, the FDA (Food and Drug Administration) classifies medicines in pregnancy in five groups:

  • A = Studies show no risk, so harm to the unborn child appears only a remote possibility
    B = Animal and human studies indicate a lack of risk but are not fully conclusive
    C = Animal studies indicate a risk but there is no safety data in humans
    D = a definite risk exists but the benefit may outweigh the risk in some people
    X = the risk outweighs any possible benefit
  • Vigabatrin is not classified, as it is not available in the USA. There is some evidence of cleft palate and so should not usually be taken in pregnancy. You should seek personal advice from your GP, who may then if necessary seek further specialist advice. If you are taking this medicine for epilepsy, then you will need to also consider the risk of seizures as well.

    Will I need blood tests ?

    You should not need any routine blood tests with vigabatrin.

    Can I drive whilst taking vigabatrin ?

    People suffering from epilepsy may drive a motor vehicle (but not a heavy goods vehicle) provided they have been free from fits for one year or if they have only had fits in their sleep for three years. You should consult your doctor about driving.

    It is essential that you report epilepsy as well as sudden disabling attacks of loss or partial loss of consciousness to the 'Driver and Vehicle Licensing Centre' (DVLC). The DVLC will then make a medical assessment of your condition consulting with your doctor(s) where necessary. For more information see leaflet 'D100' ('What you need to know about driving licensing') which is available from most post offices, or contact the Driver Enquiry Unit, DVLC, SWANSEA SA6 7JL. (Telephone: 01792 772151 between 8.15 am. to 4.30 pm. on Monday to Friday). You will need to quote your Driver Number whether you write or telephone. Your doctor will be able to advise you, and may wish to access the UK Driver and Vehicle Licensing Agency (DVLA) guidelines website, which has the current DVLA guidelines on anxiety/depression, psychotic disorders, mania and other conditions or for epilepsy. If your doctor advises you not to drive, and you continue to do so, the doctor can inform the DVLA directly, as he or she would be lawfully responsible were you to have an accident. Once told, the DVLA may wish to carry out an enquiry, but you are entitled to drive until there a decision is made.

    If you are allowed to drive remember that gabapentin can make you drowsy when you first start taking it and cause you to have difficulty concentrating. You must take great care when driving or operating any type of machinery.

    If you are allowed to drive remember that vigabatrin can make you drowsy when you first start taking it and cause you to have difficulty concentrating. You must take great care when driving or operating any type of machinery.

     


    This site is based on original work by Steve Bazire and Sarah Branch, and developed in 2007-8 by a collaboration between Mick Collins, Maureen Ng, Rowan Purdy and Steve Bazire through NWMHFT, CSIP, ABPI, UEA, and NIMH-E

    2008 Stephen Bazire, Norfolk and Waveney Mental Health NHS Foundation Trust
     

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    Many developments have been as a result of feedback from visitors.

    No site can be entirely bias-free. No matter how hard someone tries, training and background will always influence your outlook. We have, however, tried to eliminate bias, and we hope you take these pages in the spirit in which they are provided i.e. a genuine attempt to inform, educate and support.

    Information here is based on published data. References include the UK British National Formulary (BNF, published by the British Medical Association and Royal Pharmaceutical Society of Great Britain), Martindale (the extra pharmacopoea, published by RPSGB Pharmaceutical Press), Psychotropic Drug Directory (latest edition), Data Sheet Compendium (UK Manufacturers Data Sheets, published by the Association of British Pharmaceutical Industry), MicroMedex (an independent and extensive CD-ROM based drug information source), UK Psychiatric Pharmacy Group leaflets, Royal College of Psychiatrists advice and guidelines and the current medical literature. Thanks also to all those people who left e-mail comments, suggestions and requests, who have helped shape the site.