TREATMENTS FOR EPILEPSY

Drugs known as ANTICONVULSANTS

DRUG:- PHENYTOIN

Phenytoin is also available as chewable tablets.

What is phenytoin used for ?

Phenytoin is most often used in the treatment of epilepsy, to help control fits or blackouts. 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. Phenytoin is also occasionally used to relieve the symptoms of trigeminal neuralgia (a painful condition of the face) and some other conditions.

How does phenytoin work ?

Epileptic seizures (fits or blackouts) happen when an abnormal electrical discharge, like a short circuit causing a spark, occurs in the brain. Phenytoin makes these discharges less likely to happen by slowing or sedating some parts of the brain, and so helps prevent the epileptic seizures. Unfortunately it may at the same time make people feel sleepy.

How should I take it ?

Tablets and Capsules:

Phenytoin tablets and capsules should be swallowed whole with plenty of water (about a half a glass) whilst sitting or standing, so that they reach the stomach and do not stick in the throat. A drink such as fruit juice, tea or coffee could be used instead of water.

When you collect your medicine from the pharmacy or doctors check that the tablets or capsules look the same as those you had before. If not ask your pharmacist or dispenser to double check. Some tablets/capsules contain a different dose of the same drug but look almost the same.

Chewable phenytoin tablets called 'Infatabs' are also available, but only contain a low dose (50mg) of phenytoin.

Liquids:

Phenytoin is available as a suspension. Your pharmacist should give you a medicine spoon or oral syringes. Use it carefully to make sure that you measure the correct amount. Ask your pharmacist for a medicine spoon if you do not have one.

You must shake the bottle well before use. The phenytoin will settle to the bottom and cause you to receive too low a dose at the start and too high a dose at the end of the bottle.

If it is necessary for you to have an injection it will be given by a nurse or doctor.

When should I take my phenytoin ?

Take exactly as directed on the medicine label. If you feel sick or get a full feeling in your stomach after taking your phenytoin, you can take it with or after food to help reduce this. It is particularly important to take phenytoin regularly as directed by your doctor to make sure that you are getting the best control of your illness from your medication.

How long will phenytoin take to work ?

Phenytoin 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 phenytoin for ?

Phenytoin 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 phenytoin addictive ?

Phenytoin is not addictive. If, however, you have been taking phenytoin for some time you should not stop it suddenly. If you do your fits may occur again (see below). For further discussion, click here.

Can I stop taking phenytoin suddenly ?

This is a "preventative medicine". Never stop taking phenytoin suddenly or without advice from your doctor as this might mean an increase in fits or blackouts. Phenytoin will nearly always need to be withdrawn slowly. This will usually be by a slight reduction in your dose every few weeks.

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. If you are ill and vomit after taking your phenytoin, you should take that dose again. You should tell your doctor about either of these next time you meet. Missing a dose can cause your fits to return. The amount in your blood 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 ?

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 phenytoin make me drowsy ?

You may feel sleepy to start with. Care must be taken 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 phenytoin cause me to put on weight ?

It is not thought that phenytoin causes any changes in weight. 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. Phenytoin has not been reported to have a significant effect, although drowsiness and headache may have an effect on desire.

Can I drink alcohol while I am taking phenytoin ?

There is not a complete ban on drinking alcohol if phenytoin is taken, but make sure you do not take more than one or two drinks a day, as this may decrease the effect of the phenytoin. Some effects of alcohol, such as unsteadiness and drowsiness, may be worse if you are taking phenytoin.

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 phenytoin affect my other medication ?

Many drugs, including other anticonvulsants and antifungals, may affect the phenytoin in your body. As the level of phenytoin in your blood needs to be exact for you, you must tell your doctor before starting or stopping any other drugs. It is probably better to take paracetamol rather than aspirin as aspirin can occasionally upset phenytoin levels. Phenytoin may also "interact" with some heart drugs, antibiotics, steroids and treatments for stomach ulcers and arthritis. This does not necessarily mean the drugs can not be used together, just that you will need to follow your doctors instructions very carefully.

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

It is important that you let your doctor know if you are taking a contraceptive pill because phenytoin makes "the pill" less effective and your doctor may need to change you to a higher dose pill. Even with this change, the contraceptive pill may still be less effective. You may want to think about other methods of contraception e.g. condom or coil. Ask your doctor or visit your local family planning clinic for advice.

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:

Phenytoin is classified as "D". There are many possible problems associated with phenytoin in pregnancy and so you will need to seek personal advice from your GP, who may then if necessary seek further specialist advice. The risks can be reduced by e.g. adjusting doses and taking folic acid and vitamin supplements.

Will I need blood tests ?

You will need to have blood tests every few weeks after you start on phenytoin. After you have become stable, you should then need to have blood tests every three to six months to make sure that the dose of phenytoin is enough and not too much or too little for you. It is also important to have extra blood tests if you get any different or an increase in side effects, your dose is changed or any other drug you are taking is changed.

Can I drive whilst taking phenytoin ?

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 and 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: 017792 72151 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 phenytoin can make you drowsy when you first start taking it and cause you to have difficulty concentrating. You must take care when driving or operating any type of machinery.

Email your comments or feedback.
Several 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.  

Email your comments or feedback.
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.