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withdrawn.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 . . .
-
If you are taking a drug or
drugs that make little if any
difference to your seizures.
-
If, after experiencing
reduced seizures, you start to
experience an increase in
seizures.
-
If you experience any side
effects that are unpleasant,
persistent, severe or
unexpected.
-
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.
