Health Centres - Imipramine
How does it work?
Imipramine 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.
Imipramine 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, imipramine helps relieve depression.
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.
Imipramine 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, imipramine 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, imipramine 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.
What is it used for?
- Depressive illness
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Bedwetting (nocturnal enuresis) in children aged seven years and over.
Warning!
- 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.
- People who wear contact lenses should be aware that this medicine can sometimes cause dry eyes, and that wearing contact lenses during treatment may therefore irritate the surface of the eye. If you experience this, consult your doctor.
- 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
- Elderly people
- Liver disease
- Kidney disease
- Heart disease
-
Diabetes
- History of epilepsy
- People with a predisposition to seizures, eg due to alcohol/drug withdrawal, brain damage, other medicines
- Psychotic illness, eg schizophrenia
-
Bipolar affective disorder
- People receiving electroconvulsive therapy (ECT)
- History of increased pressure within the eye, eg glaucoma
- History of difficulty passing urine (urinary retention)
-
Enlarged prostate gland
-
Overactive thyroid gland
- People taking thyroid medication for an underactive thyroid gland
- Tumour of the adrenal gland (phaeochromocytoma)
- Low blood pressure (hypotension)
- Hereditary blood disorders called porphyrias.
Not to be used in
- Severe liver disease
- People who have recently had a heart attack
- Defect of the heart's electrical message pathways resulting in decreased function of the heart (heart block)
- Irregular heart beats (arrhythmias)
-
Closed angle glaucoma
-
Manic episodes of bipolar affective disorder (manic depression)
- People who have taken a monoamine oxidase inhibitor antidepressant (MAOI) in the last three weeks.
- This medicine is not recommended for treating depression in children, 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.
Pregnancy and breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- The safety of this medicine for use during pregnancy has not been established. It is not recommended for pregnant women, particularly in the first and third trimesters, unless considered essential by your doctor and the benefits to the mother outweigh the potential risks to the unborn baby. Seek medical advice from your doctor.
- This medicine passes into breast milk in small amounts. It should be used with caution by mothers who are breastfeeding, and only if the potential benefit outweighs any risk to the nursing infant. Alternatively, mothers may consider not breastfeeding while taking the medicine. Seek medical advice from your doctor.
Label warnings
- This medication may cause drowsiness. If affected do not drive or operate machinery. Avoid alcoholic drink.
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