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Epilepsy Medications

Antiepileptic Drugs [AEDs]

Anti-epileptic drugs (AEDs) are the medications used in the treatment of epilepsy. Choosing the right AED for you will depend on your epilepsy syndrome, age, gender, and many other individual factors. The aim of treatment with AEDs is to completely control your seizures without side effects. If this is not possible, the goal is to reduce the frequency or intensity of your seizures with the least possible side effects. Taking a single drug [monotherapy] is preferable. If the drug of choice doesn't control your seizures, or if unwanted side effects occur, then a second drug may be tried and the first is usually withdrawn. Only when seizures are resistant to single drug therapy should a combination of drugs [polytherapy] be necessary.

Medications used for epilepsy include:

The following table lists the medications which are most commonly prescribed for epilepsy. At the end of this section on medications we have listed each one under it common name and provided more detailed information including interactions, precautions and possible side effects.

Seizure control is the best indication that your medication is working. Poor seizure control may indicate that your current dose may need adjusting. One way, especially with the older drugs, that your doctor can establish how much medication you need is to measure how much of it is present in your blood. Other blood tests that check major organs such as liver and kidneys as well as bone marrow can also be performed. Poor seizure control may also indicate that your current medication is not working effectively and your doctor may want to change it.

Generic drugs

A generic drug is a drug based on a branded product but made by a different manufacturer. Research suggests that the minute difference between two versions of the same drug may cause problems for people with epilepsy if they are switched from one to another. While the chemicals used are exactly the same, there can be slight variations between the drugs due to the manufacturing process. For the vast majority of drugs this has little or no impact on the person taking the medication. However due to the way antiepileptic drugs work even the slightest variation in the amount of the drug taken appears to cause problems for some people with epilepsy.

It appears that any switch in medication whether it be branded to generic, generic to branded, or generic to generic may cause an increase in drug side effects, an increase in seizure frequency or breakthrough seizures in people whose seizures were previously well controlled.

People with epilepsy are advised to continue taking their prescribed medication. When a prescription is filled, check that the tablets are the same size, shape and colour, and the packaging carries the same name as prescribed by your doctor. If your pharmacist suggests that switching to another product can save you money politely refuse and insist on your usual medication. Switching drugs is not worth the risk.

Medication review

The reason you take medication is to control your seizures. You can say that your seizures are fully controlled if your seizures have stopped altogether after commencing to take your medication as prescribed. If you have not experienced any unwanted side effects during this time, you might be quite happy to continue to take the medication for the rest of your life.

Coming off medication

If you have experienced full control for two to three years, you could ask your doctor about the possibility of reducing and eventually ceasing your medication. While such a medically supervised and properly monitored withdrawal from antiepileptic medication can free you from the need to take tablets and still leave you seizure free, it is not without its risks. Some people will take this course only to find that seizures return and some of these people will find that bringing them under control a second time might not be as easy as it was the first time. Coming off medication is a decision that needs to be taken carefully, and after discussion with your doctor and those whose support you will need, should your seizures recur.

Unwanted side effects

Most tablets have unwanted side effects for some people. These can be the result of interactions with other medications, both over-the-counter medications and prescription medications. Side effects can occur when you have other illnesses that are exacerbated by the particular antiepileptic medications you are using. Side effects can also be experienced or worsened because you are not taking the tablets you have been prescribed in the way the doctor asked you to take them. For example missing tablets and taking extra doses to try to make up for what you have missed can be a disaster.

However, the most common reason for side effects is simply the interaction of your chemistry and that of the medications you are taking. While we are all different, many of the medications prescribed for us over our lifetime will be well tolerated. Yet a significant number of us will eventually find ourselves taking a tablet that does not agree with us – in other words being confronted by unwanted side effects. Fortunately, with antiepileptic medications, most disappear after the first few weeks of therapy and serious side effects are uncommon. Unwanted effects may include drowsiness/fatigue, insomnia, nausea, and weight gain, vision changes and unsteadiness and rash. Some medications may also affect emotions, behaviour, memory or the learning abilities of children. Of course some side effects are quite good. Weight loss can be seen as good, even if unintended, while weight gain is usually seen as an unwanted side effect.

Some side effects however go on for too long and show no signs of lessening. Some are especially unpleasant or severe and should not be tolerated at all. When you start taking a new medication your doctor should tell you what side effects to look out for and when to become concerned. Some reactions will require immediate attention such as allergic rash. It is important that you are aware of what might go wrong. You should read the product information sheet that is now packaged with most medications or your local epilepsy counsellor can give you a list of side effects. This is not the same as looking for trouble. It is about being sensible and not keeping things hidden that your doctor would want to know about.

Most side effects can be overcome and many will simply go away of their own accord, but some are rather more serious and you should discuss any concerns at all with your health professional. They will often be able to put your mind at rest and you will be pleased that you asked and saved yourself unnecessary worry and stress, both of which can add to the difficulty of gaining full control of seizures.

When to seek a review of your medication

A review of your medication does not mean that you will always stop taking the medication you are on. Often it will mean adjusting how much you take or how often you take it. It might mean that an additional drug is introduced and that a drug you are already using will be carefully scaled down or withdrawn.

What a review should mean is that you move closer to optimum treatment for your seizures than you would have been had you left things as they were. The closer you are to full seizure control the safer you are from any unexpected or adverse outcomes.

In the early days following a diagnosis of epilepsy your doctor will ask to see you several times to review your progress and your medication. You may be told at some point that you will have to be patient and work with the doctor to get the level of the medication right for you. Provided that the side effects you are experiencing are not severe, nor frequent, your doctor will probably want you to try the medication you were prescribed for several months until the optimum dose is found and any side effects are eliminated or significantly reduced. He or she will be more likely to try to eliminate the side effects rather than change your medication if the medication is doing a really good job controlling your seizures.

If a medication gives you no relief or if the side effects are numerous, frequent or severe, your medication can be changed. The whole process can take a matter of weeks or it can go on for a couple of years. Most people will have very good control a couple of years out from diagnosis. Even more people could have better control if they were prepared to keep trying to get their medication to its optimal level.

New drugs for epilepsy are regularly released and even if they are not listed on the Pharmaceutical Benefits Scheme you may be able to get into one of the drug trials that are the usual first step to getting the drugs registered in Australia. In almost all cases the drugs will already be available for use overseas and your doctor will be able to tell you what the risks of the drug are and what the expected advantages are. Drug trials are strictly controlled and the purpose of your participation from your point of view is basically to see if the best drug has arrived for you.

Of course you don’t have to go into a drug trial to try a new drug.

There are already many excellent antiepileptic drugs available and if your seizures or side effects are not controlled you should talk to your doctor about moving to some of the newer drugs.

Sometimes people are told that their seizures are under control when they know that they are not, or at least not fully. Do not accept anyone’s versions of “controlled” other than your own. If you are happy with 80% or 90% control then that is your decision but don’t make the mistake of thinking that you must be happy with less than full control. Why settle for pretty good control when you might achieve full control? Of course this presupposes that you are prepared to keep trying and we understand that it can be a difficult decision to keep trying new drugs when the old ones are almost right. We urge you, however, to remember that the safest way of dealing with seizures is to have them controlled.

If you want to see a neurologist your doctor can refer you if he or she hasn’t already done so. They are likely to have referred you on if your seizures were not straightforward to diagnose or to bring under control. Your epilepsy association counsellor can also help you to see a neurologist. We have many stories of people whose seizures were almost controlled but not fully and whose lives were quite literally turned around, sometimes after 10 or 15 or more years with less than full seizure control, when they had their medication reviewed and got onto one of the newer drugs. Suddenly they were fully controlled and able to do many of the things they thought they would never do again.

While we would tell you that the decision to try a different medication is your own in consultation with your doctor, we would also advise you to consider not wasting your time with seizures you don’t need to be having.

Our advice is that you ask your doctor, or a neurologist, to review your medication . . .

  1. If you are taking a drug or drugs that make little if any difference to your seizures.
  2. If, after experiencing reduced seizures, you start to experience an increase in seizures.
  3. If you experience any side effects that are unpleasant, persistent, severe or unexpected.
  4. If you are unable to gain full seizure control from you current medication.

We would also advise anyone whose seizures are not fully controlled to have their circumstances reviewed annually by their doctor and by a neurologist if possible.

Managing your epilepsy is an important part of managing your total health and an annual review will focus not only on your epilepsy but on any other health conditions that you might have that may alter the possibilities for how your epilepsy is best managed.

Over-the-counter (OTC) medicines and AEDs

It is essential to remember that over-the-counter medicines and herbal preparations that have central nervous system effects such as sedation or stimulation can have unpredictable effects on seizure control and can even cause an increase in seizure occurrence.

The table below includes information about well-documented interactions with some of the products currently available that you can obtain without a prescription. Many prescription medications that have not been included in this table can also interact with antiepileptic medicines. You should always tell the doctor you are seeing what antiepileptic medications you are on if you are about to get a script for other medicine. There are also many more possible interactions that have not been documented. It is important to ask your pharmacist or doctor about any possible effects on your antiepileptic medication or seizure control, before consuming any of these products or medications.

This information was kindly supplied by the Queensland Helpline Team within the Education and Information Unit of the Pharmacy Department of the Mater Misericordiae Public Hospital.

Prescribed medications which may lower seizure threshold

Thanks to Neil Buchanan, Emeritus Professor, University of Sydney, Sydney

Most people who have epilepsy are warned that certain substances, especially other medications and alcohol do not mix with their pills'. This is partly correct and is more valid with the older, enzyme-inducing drugs [phenytoin, phenobarbitone and carbamazepine] than with the new antiepileptic drugs.

What people with epilepsy are not sufficiently informed about are the factors that lower the seizure threshold and make them more liable to have seizures. Such factors include stress, sleep deprivation, alcohol menstruation and, especially in children, intercurrent infection and fever. Antiepileptic drugs may occasionally make seizures worse, either idiosyncratically when being introduced, or if the dose is excessive. The following table shows some medications that may provoke seizures by lowering seizure threshold, rather than by interacting with antiepileptic drugs.

We do not know how often seizures occur because a drug has altered the seizure threshold. Many reports are anecdotal. In the past two years of specialist practice I have seen 25 patients where clinical judgement would suggest a particular medication has provoked a seizure. The commonest seizure-provoking drug was pethidine. With hindsight, 19 of the 25 patients might have avoided this problem if they had known that it could have occurred. The severity of the seizures varied, but three patients were admitted to intensive care units.

The list of potential seizure-provoking medications shown is probably incomplete. The list has been compiled from personal observations, discussions with colleagues, data from the Adverse Drug Reactions Advisory Committee (ADRAC) and published product information. The purpose of compiling such a list does not imply the use of these drugs is prohibited. Rather it aims to alert doctors and people with epilepsy to medications that could provoke seizures. Attention to the mention of epilepsy in the precautions section of published product information would identify most potential problems.

With regard to anaesthetic agents, there are reports of seizures post-anaesthesia. Whether this relates to the anaesthetic agent itself or withdrawal seizures after an anaesthetic is not clear. While propofol is effectively used in the management of status epilepticus there are definite reports of seizures after its use as an anaesthetic. From the patient's point of view, the reason why is not of great concern.

The implications are:
· medical practitioners should be aware of the possibility of a change in seizures threshold
· people with epilepsy should be aware of the possibility that medicines may lower their seizure threshold
· medications which may alter the seizure threshold should only be used if really necessary and no safer alternative exists.

EMAIL epilepsy@epilepsy.asn.au    818 Burke Rd, Camberwell Victoria  3124  Australia
PHONE (03) 9805 9111    TOLL FREE 1300 852 853    FAX (03) 9882 7159

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Last modified: September 04, 2006