WHAT IS EPILEPSY
Epilepsy is a condition that affects the brain. When someone has epilepsy, it means they have a tendency to have epileptic seizures.
Anyone can have a one-off seizure, but this doesn’t always mean they have epilepsy. Epilepsy is usually only diagnosed if someone has had more than one seizure, and doctors think it is likely they could have more.
Epilepsy can start at any age and there are many different types. Some types of epilepsy last for a limited time and the person eventually stops having seizures. But for many people epilepsy is a life-long condition.
Electrical activity is happening in our brain all the time, as the cells in the brain send messages to each other. A seizure happens when there is a sudden burst of intense electrical activity in the brain. This causes a temporary disruption to the way the brain normally works. The result is an epileptic seizure.
There are many different types of seizure. What happens to someone during a seizure depends on which part of their brain is affected. During some types of seizure the person may remain alert and aware of what’s going on around them, and with other types they may lose awareness. They may have unusual sensations, feelings or movements. Or they may go stiff, fall to the floor and jerk.
What causes epilepsy?
Sometimes, doctors can find a clear cause for a person’s epilepsy. Possible causes of epilepsy include:
But in over half of all people with epilepsy, doctors don’t know what caused it. Some may have a family history of epilepsy, suggesting that they may have inherited it. Scientists are trying to find out more about how epilepsy might be inherited.
The main way doctors diagnose epilepsy is by taking a detailed description of the seizures. They may also arrange for some tests to help give them more information about the possible type and cause of the epilepsy. This can also help rule out any other conditions that could be causing seizures. These tests can include blood tests, an EEG (recording of the brainwaves) and brain scans. But there isn’t a single test that can prove if someone does or does not have epilepsy.
The main treatment for epilepsy is epilepsy medicines. These are sometimes called anti-epileptic drugs or AEDs. The medicine doesn’t cure epilepsy, but helps to stop or reduce the number of seizures.
If epilepsy medicine doesn’t work well for someone, their doctor might suggest other types of treatment. Other types of treatment include brain surgery, another type of surgery called vagus nerve stimulation, and a special diet called the ketogenic diet which is sometimes used for children.
Treatment is usually started with a first line AED. This is an AED that is tried first and taken on its own (monotherapy). Once the most appropriate AED for you has been identified, and discussed with you, you will usually start on a very low dose. This helps your body get used to the medication, and makes side effects less likely. The dose is then increased (titrated) slowly over a number of weeks until it stops your seizures. The right dose for you may be different to what is right for someone else and is sometimes referred to as your ‘individual therapeutic concentration’.
How the body absorbs, uses and removes medication changes with age. For children, AED doses are based on their body weight and so the dose increases as they get older (up to around 12 years of age). For adults, doses are not based on body weight.
For most people, once the right AED for them is found, it will stop their seizures. Although for some people it can take a bit of time to get this right, the aim is to stop your seizures by just taking one AED. However if, when the dose is increased, it does not stop your seizures, or you start to have side effects, you may want to talk to your doctor about changing to a different AED. Because different AEDs work in different ways, if one does not control your seizures it doesn’t mean that other AEDs won’t work. If you change from one AED to another, the second AED is usually added and slowly increased to a dose which is likely to work and then the original drug is slowly reduced.
If your seizures are not controlled with a single AED you may take a combination of AEDs (polytherapy). Some AEDs added to first line AED are called second line AEDs. This is slightly different for children because AEDs are not split into first and second line for treating children age 12 and under.
'Branded' drugs are the original version of a drug produced by the drug (pharmaceutical) company which developed the drug. To start with, only the company that developed the drug can produce it. This is called being ‘on patent’, and the drug will have a brand name that only that company can use. For example, Tegretol is the brand name of the AED carbamazepine.
All drugs have an ‘active ingredient’ (the part of the drug that treats the condition for which you take it). This ingredient is often referred to as the ‘generic’ name.
Once a branded drug has been on the market for a number of years, other companies are allowed to start producing their own version of the drug (after it becomes ‘off patent’). These other companies might call their version of the drug by just the generic name, such as ‘carbamazepine’, or they might give their version another name (sometimes called a ‘branded generic’), such as ‘Carbagen’.
Several drug companies might produce their own versions of a generic drug, but they will all contain the same active ingredient.
Each company’s version of a drug will usually look different, so that you can tell different versions apart, and you can recognise a particular drug from a specific drug company. The differences include the size, colour and any writing on the tablets or capsules themselves. The packaging will also look different.
Although AEDs with the same generic name have the same active ingredient, this does not mean that they are exactly the same. This is because drugs contain other ingredients, such as colouring and binding agents (ingredients that hold the tablet together), which can be different from one version to another. In some cases, these other ingredients might affect how the drug is absorbed in the body, which could affect how well the active ingredient works in the brain to stop seizures.
When a new generic version of a drug is developed, it has to be shown to be ‘bioequivalent’ (have a similar effect) – within a certain range – to the original ‘on patent’ brand. This means they have to be ‘similar enough’ to the original in how they work in the body and the amount of active ingredient that gets to the brain. However, a generic version only has to compare in this way to the brand version, not to other generic versions. So, two generic versions might have greater differences between them in the way they work, than the differences between a generic and a brand version.
A ‘brand’ version of an AED is not ‘better’ or ‘worse’ than a generic version of that drug. The important thing is that you and your doctors find a version of a drug which suits you, and you take this version consistently. ‘Consistency of supply’ means getting the same version of a drug with every prescription.
Concerns about switching between drugs
There are several reasons why switching between different version of AEDs may be a problem for some people.
If you have a neurologist, you can talk to them about your concerns. If they agree that you need to always have the same version of AEDs, you can ask them to pass this information on to your GP, with instructions on how to prescribe the same version each time.
Your GP is usually responsible for your prescriptions. If you are taking a brand version of your AED, you can ask them to write the brand name on your prescription. If you take a generic version, ask them to write the name of the manufacturer, with the generic name.
If you use the same pharmacy regularly, your pharmacist may keep a record of what medication you take. They might be able to make a note to get the same version of your AEDs for you each time. If pharmacists don’t have your usual version in stock, you can ask for your prescription back, and take it to another pharmacy. Check that you have your correct AEDs while you are at the pharmacy counter, as they won’t be able to change it after you leave the counter.
Get to know your medication
It can be a good idea to keep a list of your AEDs: the generic name, any brand name, and the name of the manufacturer. You could also make a note of the colour and shape, to help you recognise it. This might help you to check your prescription from the doctor, or from the pharmacy.
Helping you to take your AEDs
Other things that might help you to take your AEDs, and to get the best effect from them include the following:
Your epilepsy review checklist
What are ‘first-’ and ‘second- line’ AEDs?
AEDs are licensed to use for controlling particular types of seizures. First-line and second-line refers to how AEDs are selected and used for the treatment of epilepsy and particular types of seizures.
First-line AEDs are the AEDs that are usually considered first when starting epilepsy treatment. They tend to be used on their own (monotherapy). They include sodium valproate and carbamazepine. Which one is chosen depends on the type of seizures the person has.
Second-line AEDs are AEDs that are usually taken alongside first-line therapy (also called adjunctive therapy) and are therefore they are generally used as polytherapy. They include topiramate and gabapentin. Second-line AEDs also include AEDs that were used as first-line treatments but that are no longer generally considered as a first treatment option when treatment is started.
However, as treatment with AEDs is always individualised, in some cases the neurologist may use his specialist knowledge and decide to put an individual on monotherapy with a second-line rather than first-line drug.
Monotherapy is taking just one drug (mono = one). If you are on monotherapy you usually take a single first-line drug. If you take more than one drug (either more than one first-line drug, or first-line and second-line drugs) this is called polytherapy (poly = many).
Neurologists often use monotherapy at the start of epilepsy treatment. Taking just one AED makes treatment simpler: there are no interactions with other drugs; it reduces the chance of getting side effects; and it is clear to see if the drug works or not. If a single AED does not stop your seizures the options are to try a different first-line drug, or to add-on a second drug.
Taking more than one drug (polytherapy) means that there may be different side effects from each of the different drugs. Your neurologist will have to consider which side effects may be from which drug. He (or she) will also need to be aware of possible interactions between the drugs, and, if your seizures become better controlled, may find it hard to see which drug is working best.
AEDs can be divided into two groups according to when they where developed and how long they have been around for.
Newer drugs (licensed after 1989) include lamotrigine, gabapentin and topiramate. Older drugs (licensed before 1989) include phenytoin, carbamazepine and sodium valproate.
When you compare the older and newer drugs it is not as simple as ‘newer drugs are better because they have been developed more recently’ or that ‘older drugs are better because they have stood the test of time and are still used’. Again, like most things in the treatment of epilepsy, there are positives and negatives to each.
The positives and negatives about older drugs include:
The positives and negatives about newer drugs include:
So the decision about which AEDs to choose is more complicated than their age alone.
Choosing AEDs depends on:
In this article we answer some of the most commonly asked questions about taking AED's, including:
One of the questions people often ask is: 'Will I have to take this medication for the rest of my life?' Read that sentence again. It’s interesting that they use the term ‘have to’.
The ‘old style’ of patient/doctor interaction was called adherence because patients were expected to stick to the course of treatment their doctor prescribed, without question. In this relationship the doctor ‘knew best’ and the patient ‘did as they were told’. In other words, the patient wasn’t really involved in making decisions about their treatment.
Today, many doctors recognise that people know a lot about their medical condition and want to play a part in any decisions about treating it. For some of us this approach can feel strange; obviously, a doctor has trained for years in medical school to learn about conditions and treatments whereas we, as patients, don’t have that training — so how can we know which treatment is right?
The basis of this new approach is called concordance, or informed decision-making, in which the doctor gives enough information about the options for treatment so that we can decide, in partnership with the doctor, what we want to do.
The keys to concordance are information and choice: knowing the risks and benefits of taking — or not taking — treatments so that together we can discuss the options and together decide what we want to do.
With regard to epilepsy and AEDs, weighing up the risks and benefits of taking or not taking treatments can include the following issues:
How important these risks and benefits are will vary from one person to another and will depend on individual circumstances: the risk of accidents or injuries due to seizures will depend on the type of seizures you have, how often they happen, and how they affect you; the effects of taking AEDs will vary depending on the AED and how your body responds to it. Ultimately the decision is yours, but having the input and support from your doctors can help you to weigh up these points and come to a decision that you are happy with. Taking part in making this choice may also help you to feel more in control, which might be important if your epilepsy makes you feel you have lost some control over your life.
How often you take an AED (once, twice or possibly three times each day) depends on its half-life. The half-life of a drug is the length of time it takes for the original amount of the drug to reduce by half. The half-life is used to measure the concentration of the drug in the blood, which is not exactly the same as the dose of drug you take.
When you take a drug it takes time to be absorbed into your blood. When it is in your blood the amount can be measured; this is expressed as the drug’s ‘concentration’ or ‘level’, which relates to how much of the active ingredient of the drug is available to work. Once the drug has done its work it becomes metabolised (broken down) and eliminated (removed) from the body. In simple terms, when the drug reaches its half-life half of it is still in the blood and half of it has been metabolised and eliminated.
The aim of taking AEDs regularly is to keep the level in the blood as stable as possible. Some AEDs have a half-life of 24 hours so they are taken once a day. Those that have a half-life of 12 hours are taken twice a day, and those with a half-life of eight hours are taken three times a day. The shorter the half-life of the AED the more often it is taken.
When considering how much medication someone takes we look at two different things. Firstly, we look at their ‘average’ dose — this is a measure of the number of tablets they take and how much active ingredient each tablet contains. For example, for an adult an average dose range for carbamazepine is 600–2000mg per day and for sodium valproate it is 400–2000mg per day. But how helpful is this? These figures are a very general guide but they are not individualised to each person: some people may have their seizures controlled on a dose lower than the bottom dose or higher than the top dose.
The second way of monitoring medication is to look at the amount of an AED in the blood and compare this to a reference range. The reference range is a range of concentrations of an AED within which most people will get a benefit from the drug (that is, it will stop the seizures). Below the reference range the drug is unlikely to work (that is, it will not stop the seizures) whereas above it, toxic effects (that is, reactions because the dose is too high) are likely to happen. Again, this is a general guide and not specific to an individual.
By monitoring drug levels in an individual and seeing what amount of an AED gives them the best seizure control, it is possible to work out an individualised therapeutic range for them. This range will vary from one person to another but will often fall within the general reference range for that AED.