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Testing
of new medicine
Tests
on animals
Tests on human beings
Blind trials
Informed consent
The future
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The medicines available today are
much more effective and have fewer side effects than the old drugs
for treating epilepsy. There is, however, still need to try to
discover new antiepileptic drugs, with even better effects and
even fewer side effects.
Even though many people with epilepsy
can become completely free of seizures, there is still a considerable
number for whom this cannot be achieved. In many cases the "costs"
of becoming free of seizures would be high, in the form of unacceptable
side effects.
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Tests on animals
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New chemical substances
are often developed by the research departments of medical firms.
By testing on animals it can be found out if the drug has an effect
on seizures. The tests are carried out on animals which either have
congenital epilepsy, or have had epilepsy provoked. If the drug
seems to work, more experiments on animals are made, in which it
is given in different doses each day in order to find out when side
-effects appear. All possible side-effects are tested for. The
effect on different types of seizures, in different species of animal,
is tested in order if possible to foresee which type of seizure
in human beings the drug might be effective against. If these tests
, which may take many years, are successful, the time has come to
test the drug on human beings. |
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Tests on human
beings
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Voluntary "guinea pigs"
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At first the drug is given to
healthy voluntary "guinea pigs", who only receive a single dose,
or many very small doses. The decisive factor is if the drug can,
in fact, be tolerated by man. Tests on animals are by no means a
guarantee that this will be the case. If no serious side effects
appear, a longer treatment is tried, in which the body's absorption
and breaking down of the drug are looked at. From this it can be
ascertained how many doses per day should be given to maintain a
stable concentration in the blood. |
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People with epilepsy
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When the drug has been tried
on healthy human "guinea pigs", the time has come to try it on people
with epilepsy to find out whether it has an effect on seizures,
and what dosage would be needed to prevent seizures. People who
take part in these early tests of new antiepileptic drugs are always
have severe epilepsy, which despite the best treatment currently
available, cannot be satisfactorily controlled. The new medicine
is added to the treatment the person is already receiving. At this
point in time no one knows if it will have any effect, therefore
one cannot taking the risk of treating with it alone. |
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Blind trials
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Both people with epilepsy and
doctors often expect (too) much of new drugs. This can come to prejudice
results during testing. It has been shown that simply the belief
that a new drug will have an effect can alter the frequency of seizures.
This can happen although the new drug may have no effect at all
in fact. Many people with epilepsy have experienced that their "state
of mind" can play a considerable part in the frequency of seizures.
It often happens that expectation, stress, going into hospital or
something other, not connected to the medical treatment, can affect
the frequency of their seizures. To avoid the results being affected
in this way, so-called "blind" tests are made. |
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Double blind trials
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These can be made in various
different ways. The most usual is the "double-blind " trial, where
both doctor and patient are "blind" as to the treatment the patient
is receiving. Lots are drawn, and some of the patients are treated
with the new drug, and some with a "placebo" which has no effect
whatsoever, but looks and tastes identical to the drug being tested.
In this way the effect which can be accredited belief in the new
drug can be discounted in the final assessment. |
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Cross-over trials
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The investigation can consist of
two equally long periods where lots are drawn to decide who is
to be treated and with what. Half of those taking part receive
the placebo first, and then the new drug. The other group is treated
the other way round. The drawing of lots, and the packing of the
medicine and placebo is carried out by people who have nothing
to do with the trials at all.
By comparing the number of seizures
in the two periods, one can find out if the new drug has an effect
which is better than that of the placebo. It is not unusual for
there to be a fall in the number of seizures while treatment is
being given with the placebo, just as "side effects" are sometimes
also seen! In these tests treatment with the new drug and the
placebo will always be in addition to the usual treatment the
person receives.
This method of testing has led to
questioning as to whether new medicines are put to a very "hard"
test, as they must compete with the medicine which is being given
already.
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Testing of new medicine
alone
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Trials of new medicines have
therefore been made on people who are going to have epilepsy surgery.
Their medicine is withdrawn over a period, in order to record their
seizures on video-EEG. In the period when they are not receiving
any medical treatment, the new drug can be tested, without it having
to "compete" with any other medicine. |
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Informed
consent
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In order to take part in a "
blind" trial, it is necessary that one is fully informed about the
tests and first after that consents to take part. If such tests
show that a new drug is effective, a withdrawal of the other medicine
taken will be attempted in the next round of tests, in order to
judge the effect of the new drug alone. If it works well alone,
it will be tried on people with newly diagnosed epilepsy, who have
not previously received treatment. Further blind trials, where the
new drug is compared to the known antiepileptic medicines will be
the last stage finding the new drug's place in the treatment of
epilepsy. |
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The future
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Development of new medicine
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Finding new antiepileptic
medicines takes a long time and is very costly. Compared to many
other illnesses which need medical treatment, epilepsy is relatively
rare. The sale of antiepileptic drugs is not large, and the drug
firm's chance of making money is limited. This led to the situation
where the number of antiepileptic drugs which have come onto the
market over the past 15 years, could be counted on one hand.
Thanks to the government authorities
in the United States of America, who carry out the preliminary
tests on animals of new chemical substances, a cooperation has
come into being between many medicinal firms. This has led to
us now being in the fortunate situation of having a considerable
number of promising new drugs ready for trials on man. This will
hopefully be of benefit to many people with epilepsy.
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