A theophylline-based bronchodilator for asthma and COPD
Aminophylline
An airway-opening medicine used in asthma and COPD, given into a vein in hospital or as slow-release tablets.
What is Aminophylline?
Aminophylline is a theophylline-based medicine used to open the airways in asthma and COPD. It can be given as a drip into a vein during a severe flare-up in hospital, or as slow-release tablets for ongoing use. Its main challenge is a narrow safety margin: the right amount and a slightly-too-much amount are close together, so blood levels are usually checked. Too much can cause nausea, a fast or irregular heartbeat and, in serious cases, fits, and it interacts with many other medicines.
Education and reference only. This is a plain-language guide to Aminophylline — 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
Aminophylline is a bronchodilator, meaning it relaxes and opens the airways, and it is closely related to theophylline (aminophylline is broken down to theophylline in the body). It is used in asthma and chronic obstructive pulmonary disease (COPD) to help breathing, either as an injection or drip into a vein in hospital during a severe attack, or as slow-release tablets taken regularly. It is an older treatment that is used less often now that inhalers and other options exist, partly because it needs careful handling. It is prescribed and monitored carefully because the safe range is narrow.
How it works
Aminophylline relaxes the muscle around the airways and helps keep them open, making it easier to breathe in asthma and COPD. It is a xanthine, working in a different way from inhaled relievers and steroids, which is why it is sometimes added when those are not enough. Because the amount that helps and the amount that causes harm are close together, the body's level of the medicine is often measured with a blood test to keep it in the safe zone. Many things, including other medicines, smoking and some illnesses, change how quickly the body clears it, which is why the dose has to be tailored and watched.
Company & origin
Originated / developed by: Generic (long-established).
A long-established medicine used in the UK to open the airways in asthma and COPD, given as a drip in hospital or as slow-release tablets.
What it treats
Conditions Aminophylline is used for
Practical use
How to take Aminophylline
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- If you take slow-release tablets, swallow them whole with water and do not crush or chew them.
- Try to stay on the same brand of tablet, as different brands can be absorbed differently and change your level.
- Take it regularly at the times you are told, as steady levels matter for it to work safely.
- Tell your team if you start or stop smoking, or develop an infection, as these change how your body handles it.
- Report feeling sick, a fast or irregular heartbeat, shakiness or any fit straight away, as these can be signs the level is too high.
Weighing it up
Advantages & disadvantages of Aminophylline
Advantages
- Helps open the airways in asthma and COPD, working in a different way from inhalers.
- Can be given as a drip in hospital during a severe flare-up or as slow-release tablets for ongoing use.
- A long-established option that can be added when other treatments are not enough.
Disadvantages
- Has a narrow safety margin, so blood levels usually need to be checked.
- Too much can cause nausea, a fast or irregular heartbeat and, in serious cases, fits.
- Interacts with many other medicines, and smoking and infections also change its level.
Practical use
Good to know
The single most important thing about aminophylline is its narrow safety margin: the helpful amount and a toxic amount are close together, so blood levels are usually checked to keep it in range. Signs that the level may be too high include feeling sick, being sick, a fast or pounding heartbeat, feeling shaky or restless and, in serious cases, fits, so these should be reported straight away. It interacts with a long list of other medicines and with smoking and certain infections, all of which can change its level, so it is important to give a full medicines and smoking history and to tell your team if you start or stop smoking. Slow-release tablets should be swallowed whole and the same brand kept where possible, as switching brands can change the level. It is a medicine that rewards careful, consistent use and regular review.
Who should not take it / use with caution
- People who have had a serious allergic reaction to aminophylline or theophylline should not take it.
- It is used with great care in people with heart-rhythm problems, certain heart conditions, an overactive thyroid or a tendency to fits.
- It is used with caution in people with liver problems and in older people, who may clear it more slowly, with closer monitoring.
Monitoring
- Blood tests to check the level of theophylline and keep it within the safe range.
- Watching for signs of too high a level, such as nausea, a fast heartbeat or shakiness.
- Reviewing other medicines, smoking status and any new illness, as these change the level.
Side effects
- Nausea, being sick or stomach upset, which can also be an early sign of too high a level.
- A fast or pounding heartbeat, feeling shaky, restless or having trouble sleeping.
- Headache in some people.
- Rarely but seriously, an irregular heartbeat, dangerously low potassium or fits, which need urgent medical attention.
Key interactions
- Many medicines raise its level, including some antibiotics (such as certain macrolides and quinolones) and some antifungals, increasing the risk of toxicity.
- Some medicines lower its level, including certain epilepsy medicines and the herbal remedy St John's wort, which can make it less effective.
- Smoking speeds up how fast the body clears it, so starting or stopping smoking can change how much you need.
Available as: Slow-release tablets taken by mouth, and a solution for a drip or injection into a vein in hospital.
Answers
Aminophylline: frequently asked questions
What is aminophylline used for?
It is used to open the airways in asthma and COPD, given as a drip in hospital during a severe attack or as slow-release tablets for ongoing use.
Why do I need blood tests?
Aminophylline has a narrow safety margin, so blood tests are used to check the level and keep it in the safe range, as too much can be harmful.
What are the signs of too much?
Feeling sick, being sick, a fast or pounding heartbeat, feeling shaky or restless and, in serious cases, fits; report these straight away.
Why does smoking matter?
Smoking speeds up how fast your body clears the medicine, so starting or stopping smoking can change how much you need, so tell your team.
Can I switch tablet brands?
It is best to stay on the same slow-release brand where possible, as different brands can be absorbed differently and change your level.
The wider class
About Theophylline-based bronchodilator (xanthine)
Aminophylline belongs to the theophylline-based bronchodilator (xanthine) 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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