Carbamazepine may be prescribed to individuals diagnosed with bipolar
disorder who are unresponsive to Lithium or who have four or more
'episodes' of distress in a year (rapid cycling bipolar). It is also
prescribed for the treatment of epilepsy and trigeminal neuralgia (a
type of facial pain).
How Carbamazepine interacts with/affects the brain
Carbamazepines mechanism of action in psychiatric disorders is not fully
understood. It's usefulness in the treatment of epilepsy results from
lowering the threshhold at which a neuron is able to generate an
impulse, fire and release neurotransmitters. It is thought to do this by
inhibiting benzodiazepine receptors. Theoretically, if there was a
region of the brain that regulated mood, inhibiting these neurons from
firing and releasing neurotrasmitter might aid in mood regulation.
Carbamazepine is also able to inhibit adrenergic receptors, which are
activate by noradrenaline/adrenaline. In doing this it would cause a
rise in noradrenaline, a chemical which has been implicated as being
deficient in depression, thus Carbamazepines anti-depressant effects.
Carbamazepine is also able to block sodium channels, increase the
expression of other adrenergic receptors and decrease calcium flow into
cells, though how these effects are linked to mood stabilisation are
Carbamazepine: Adult max = 1.6g daily, usual range 400-600 mg daily
Side effects of Carbamazepine
Nausea and vomiting, dizziness, drowsiness, headache, confusion and
agitation, double vision; constipation or diarrhoea, loss of appetite,
rashes, reduced levels of white blood cells, reduced levels of platelets
in the blood, anaemia, jaundice, hepatitis (inflammation of the liver),
acute renal failure, severe skin reactions, hair loss, increased risk of
clot formation, aches in the joints, fever, protein in the urine, lymph
node enlargement, cardiac conduction disturbances (sometimes
arrhythmias), disorders of movement, abnormal spontaneously occurring
tingling or sensations of numbness, depression, impotence (and impaired
fertility), enlargement of the breasts, milk production and secretion of
the breasts, aggression, photosensitivity, low body sodium, oedema
(swellings resulting from collections of fluid), irritation of the
lungs, disturbances of bone metabolism.
When discussing coming off psychiatric drugs the terms withdrawal and
discontinuation will be used interchangeably.
There are limited studies looking at the effects of
withdrawal/discontinuation of Carbamazepine. Those that do are looking
at whether there is an increased frequency of seizures in those who take
Carbamazepine for epilepsy. There has been one study published looking
at whether Carbamazepine withdrawal results in a 're-bound' mania,
similar to the effects of Lithium withdrawal, however the study numbers
were small. All six individuals included in the study had a diagnosis of
bipolar disorder, were taking carbamazepine and had been 'well' for at
least six months prior to discontinuing carbamazepine. What the study
doesn't clarify is how fast the individuals discontinued the
carbamazepine, whether they stopped all at once or reduced gradually
over a period of weeks. In the study none of the individuals had a manic
episode within 3 months of carbamazepine discontinuation, one individual
became 'moderately' depressed. The full study can be viewed at the
Macritchie KAN and Hunt NJ. Does 'rebound mania' occur after stopping
carbamazepine?: A pilot study. /J Psychopharmacol/ 2000; 14:266
Rates of withdrawal
As with all psychiatric drugs we suggest an approach of better safe than
sorry. The trends tend to suggest that coming off drugs all at once can
be dangerous and that individuals are more likely to develop withdrawal
symptoms if this approach is taken, as the brain doesn't have time to
adapt to the absence of a drug it has become used to. The slower the
withdrawal, the less likely an individual is to run into difficulties.
We would recommend that individuals coming off carbamazepine, do so by
gradually reducing the dose over a period of time and allow at least two
weeks pass between each dose reduction.
As for how much to reduce by at a time, this is not a finite science. We
would recommend that the maximum a dose should be reduced by is 25%
every two weeks, this would mean it would take an individual
approximately 2 months to fully come off carbamazepine. But the aim is
not to come off quickly, it is to come off safely, with as little
inconvenience as possible.
So if an individual wished to come off carbamazepine and they were
currently taking 600mg daily, the first two weeks they would reduce to
450mg, the next two weeks 300mg, the next two weeks 150mg etc. For other
psychiatric medications some individuals have struggled with the last
stages of withdrawal e.g. from 150mg to 0mg. Therefore you could reduce
the last doses in smaller increments e.g. 100mg for a week, then 50 mg
for a week etc. But everyone is different and you will be able to taper
your withdrawal to your own needs.
Carbamazepine is also available in liquid form, which will enable you to
reduce at a very gradual pace should you choose to reduce the rate of
If you are taking any medications other than your psychiatric drugs it
is worthwhile speaking to your GP about what potential interactions your
psychiatric medications may have with your other medications.