A tricyclic-related antidepressant
Amoxapine
An older tricyclic-related antidepressant used for depression, now rarely used in the UK.
What is Amoxapine?
Amoxapine is an older antidepressant of the tricyclic-related type, used to treat depression. It is largely a US product and is rarely used in the UK now, with safer antidepressants usually preferred. Its main concerns are that it is dangerous in overdose, with a risk of fits and heart-rhythm problems, and that it can cause antimuscarinic effects such as dry mouth, constipation and blurred vision. Unusually for an antidepressant, it can also cause movement disorders and neuroleptic-type effects, so it is used with care and under medical supervision.
Education and reference only. This is a plain-language guide to Amoxapine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Amoxapine is an antidepressant related to the tricyclic group of medicines, used to treat depression. It is an older medicine and is largely a United States product, rarely used in the UK today, where newer antidepressants such as SSRIs are usually preferred because they are safer and better tolerated. It is taken by mouth. It shares the typical features of tricyclic-type antidepressants, such as antimuscarinic side effects and danger in overdose, and it has some additional effects more usually seen with antipsychotic medicines.
How it works
Amoxapine works mainly by increasing the levels of the brain chemicals noradrenaline and serotonin, which are involved in mood, helping to lift depression over a few weeks. Like other tricyclic-type medicines, it also blocks several other receptors in the body, which produces antimuscarinic effects such as dry mouth and constipation and contributes to its danger in overdose. Unusually, one of the substances it is broken down into has antipsychotic-like activity, which is why amoxapine can also cause movement disorders and other neuroleptic-type effects not typical of most antidepressants. It is taken regularly, as the antidepressant effect builds up gradually.
Company & origin
Originated / developed by: Generic (rarely used in the UK).
An older tricyclic-related antidepressant, largely a US product and rarely used in the UK, prescribed for depression.
What it treats
Conditions Amoxapine is used for
Practical use
How to take Amoxapine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth as prescribed and give it a few weeks to start working, as the effect builds up gradually.
- Do not stop it suddenly; any change should be made gradually under your prescriber's guidance.
- Report any unusual movements, stiffness, restlessness or twitching, as these neuroleptic-type effects need attention.
- Tell your prescriber promptly about a fast or irregular heartbeat, fainting or fits.
- Watch for any worsening mood or thoughts of self-harm, especially early on, and seek help if they occur.
Weighing it up
Advantages & disadvantages of Amoxapine
Advantages
- Can be an effective treatment for depression by raising mood-related brain chemicals.
- Taken by mouth.
- A long-established medicine with decades of use, mainly in the United States.
Disadvantages
- Dangerous in overdose, with risks of fits and heart-rhythm problems.
- Commonly causes antimuscarinic effects such as dry mouth, constipation and blurred vision.
- Can cause movement disorders and neuroleptic-type effects, unusual for an antidepressant; rarely used in the UK.
Practical use
Good to know
There are a few important things to understand about amoxapine. First, like other tricyclic-type antidepressants, it is dangerous in overdose, with risks of fits and dangerous heart-rhythm changes, so only the amount prescribed should be kept and taken, and it is used with particular care where overdose is a concern. Second, it commonly causes antimuscarinic effects such as dry mouth, constipation, blurred vision and difficulty passing urine. Third, and unusually for an antidepressant, it can cause movement disorders and neuroleptic-type effects, including restlessness, stiffness or abnormal movements, which should be reported. As with all antidepressants, it can take a few weeks to work, and it should not be stopped suddenly. Younger people in particular should be watched for any worsening mood or thoughts of self-harm early in treatment. It is largely a US product and rarely used in the UK.
Who should not take it / use with caution
- People who have had a serious allergic reaction to amoxapine should not take it.
- It is generally avoided soon after a heart attack and in people with certain heart-rhythm problems.
- It is used with caution in people prone to fits, with glaucoma, urinary problems or an enlarged prostate, and where overdose is a concern.
- It should not be taken together with, or close to, MAOI antidepressants.
Monitoring
- Reviewing mood and watching for any worsening or thoughts of self-harm, especially early in treatment.
- Watching for movement disorders and neuroleptic-type effects.
- Checking the heart's rhythm where there are concerns, and reviewing side effects over time.
Side effects
- Antimuscarinic effects such as dry mouth, constipation, blurred vision and difficulty passing urine.
- Drowsiness, dizziness, especially on standing, and weight gain.
- Movement disorders, restlessness, stiffness or abnormal movements (neuroleptic-type effects).
- Rarely but seriously, fits, a fast or irregular heartbeat, and danger in overdose, needing urgent attention.
Key interactions
- It must not be combined with, or used close to, MAOI antidepressants, as this can be dangerous.
- It is used with care alongside other medicines that affect the heart's rhythm or cause drowsiness.
- Alcohol and other sedating medicines can add to drowsiness, and other medicines acting on serotonin should be reviewed.
Available as: Tablets taken by mouth.
Answers
Amoxapine: frequently asked questions
What is amoxapine used for?
It is an older tricyclic-related antidepressant used to treat depression, though it is largely a US product and rarely used in the UK now.
Why is it not used much in the UK?
Newer antidepressants are usually preferred because they are safer and better tolerated; amoxapine is dangerous in overdose and has unusual movement-related effects.
What unusual side effects can it cause?
Unlike most antidepressants, it can cause movement disorders and neuroleptic-type effects such as restlessness, stiffness or abnormal movements, which should be reported.
Can I stop it suddenly?
No. It should not be stopped suddenly; any change should be made gradually under your prescriber's guidance to avoid withdrawal effects.
How long does it take to work?
Like other antidepressants, it can take a few weeks to start working, so keep taking it and discuss any worsening mood with your prescriber.
The wider class
About Tricyclic-related antidepressant
Amoxapine belongs to the tricyclic-related antidepressant class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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