Amitriptyline is a type of medicine called a
tricyclic antidepressant (TCA). This type of medicine
acts on nerve cells in the brain.
In the brain there are numerous different chemical compounds
called neurotransmitters. These act as chemical messengers between the nerve
cells. Serotonin and noradrenaline are neurotransmitters and they have various
functions that we know of.
When serotonin and noradrenaline are released from nerve cells
in the brain they act to lighten mood. When they are reabsorbed into the nerve
cells, they no longer have an effect on mood. It is thought that when
depression occurs, there may be a decreased amount of serotonin and
noradrenaline released from nerve cells in the brain.
Amitriptyline works by preventing serotonin and noradrenaline
from being reabsorbed back into the nerve cells in the brain. This helps
prolong the mood lightening effect of any released noradrenaline and serotonin.
In this way, amitriptyline helps relieve depression.
Amitriptyline can cause side effects such as drowsiness. This
means it may be useful in treating depression in people who are also anxious
and agitated, or who are suffering from disturbances in sleep.
It may take between two to four weeks for the benefits of this
medicine to appear, so it is very important that you keep taking it, even if it
doesn't seem to make much difference at first. If you feel your depression has
got worse, or if you have any distressing thoughts or feelings in these first
few weeks, then you should talk to your doctor.
Amitriptyline is also occasionally used for a completely
different purpose - for the treatment of bedwetting in children. It works in
this situation by blocking receptors called cholinergic or muscarinic receptors
that are found on the surface of muscle cells in the wall of the bladder. This
prevents a chemical called acetylcholine from acting on these receptors.
Acetylcholine acting on these receptors normally causes the muscle in the
bladder wall to contract, and the bladder to empty. By reducing this,
amitriptyline helps the muscle in the bladder wall to relax. This reduces
unstable, involuntary contractions of the bladder, and thereby increases the
capacity of the bladder to hold urine. This in turn reduces the need to pass
urine. When used for this purpose, amitriptyline should generally only be used
for a maximum of three months, unless a full physical examination is given and
the child is fully re-assessed.
Depression is associated with an increased risk of suicidal
thoughts, self-harm, and suicide. You should be aware that this medicine may
not start to make you feel better for at least two to four weeks. However, it
is important that you keep taking it in order for it to work properly and for
you to feel better. If you feel your depression has got worse, or if you have
any distressing thoughts or feelings, particularly about suicide or harming
yourself in these first few weeks, or indeed at any point during treatment or
after stopping treatment, then it is very important to talk to your doctor.
This medicine may cause drowsiness and could reduce your
ability to drive or operate machinery safely. Do not drive or operate machinery
until you know how this medicine affects you and you are sure it won't affect
your performance.
It is recommended that you avoid drinking alcohol while taking
this medicine because it may enhance drowsiness.
This medicine can occasionally cause your blood pressure to
drop when you move from a lying down or sitting position to sitting or
standing, especially when you first start taking the medicine. This may make
you feel dizzy or unsteady. To avoid this try getting up slowly. If you do feel
dizzy, sit or lie down until the symptoms pass.
Antidepressants may cause the amount of sodium in the blood to
drop - a condition called hyponatraemia. This can cause symptoms such as
drowsiness, confusion, muscle twitching or convulsions. Elderly people may be
particularly susceptible to this effect. You should consult your doctor if you
develop any of these symptoms while taking this medicine so that your blood
sodium level can be checked if necessary.
This medicine can cause a dry mouth, which may increase the
risk of tooth decay with long-term use of the medicine. It is therefore
important to visit your dentist regularly for check-ups.
You should not suddenly stop taking this medicine, as this can
cause withdrawal symptoms such as nausea, vomiting, loss of appetite, headache,
giddiness, chills, insomnia, restlessness or anxiety. Withdrawal symptoms are
temporary and are not due to addiction or dependence on the medicine. They can
usually be avoided by stopping the medicine gradually, usually over a period of
weeks or months, depending on your individual situation. Follow the
instructions given by your doctor when it is time to stop treatment with this
medicine.
During long-term treatment with this medicine your doctor may
want to monitor your heart and liver function and take
blood tests to monitor the levels of blood cells in your
blood. You should let your doctor know if you experience symptoms such as a
fever or sore throat while you are taking this medicine.
Changes in behaviour have been seen in children taking this
medicine to treat bedwetting. For further information talk to your doctor or
pharmacist.
Use with caution in
Children
Elderly people
Decreased liver function
Heart disease
History of difficulty passing urine (urinary
retention)
This medicine is not recommended for treating depression in
children under 16 years of age, or for treating bedwetting in children under
seven years of age.
This medicine should not be used if you are allergic to one or
any of its ingredients. Please inform your doctor or pharmacist if you have
previously experienced such an
allergy.
If you feel you have
experienced an allergic reaction, stop using this medicine and inform your
doctor or pharmacist immediately.
