Health Centres - Amnivent SR (discontinued in the UK)
How does it work?
Amnivent SR prolonged release tablets contain the active ingredient aminophylline. Aminophylline is a mixture of a medicine called theophylline and a substance called ethylenediamine. The ethylenediamine makes the theophylline more soluble in water. The action of this medicine is actually due to the theophylline.
Theophylline is a type of medicine called a xanthine bronchodilator. It is used to open the airways. Theophylline works by causing the muscles surrounding the airways to relax, by a mechanism that is not fully understood. This allows the airways in the lungs to open.
In conditions where the airways tighten, such as asthma or chronic obstructive pulmonary disease (COPD, eg emphysema and chronic bronchitis) , it is difficult for air to get in and out of the lungs. By opening the airways, theophylline makes it easier to breathe.
Amnivent SR tablets are designed to release the theophylline slowly over 12 hours. They are taken as a regular twice daily treatment to help keep the airways relaxed and open all the time. The tablets should be swallowed whole, as crushing or chewing them will stop the prolonged release action from working.
What is it used for?
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Asthma
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Chronic obstructive pulmonary disease
Warning!
- Theophylline has a narrow margin between the blood level needed for the medicine to be effective and the blood level that is high enough to cause side effects. Your doctor may need to take a blood test to monitor your theophylline level from time to time, to make sure that you taking the right dose to put you within the correct range.
- Smoking tobacco or cannabis, chewing tobacco or taking snuff can increase the removal of theophylline from the body and so decrease your theophylline blood level. You should tell your doctor if you are a smoker, as you may need a higher than normal dose of theophylline. You should also tell your doctor if you are giving up smoking, as this may mean your dose will need reducing. Acute viral infections can increase your theophylline blood level. You should consult your doctor if you get a feverish infection, so that if necessary your theophylline blood level can be checked.
- If this medicine doesn't seem to work as well, or for as long as usual, or you need to use your reliever inhaler (eg salbutamol or terbutaline) more often than usual to relieve wheezing or chest tightness, you should consult your doctor as soon as possible. It may be that your asthma or COPD is getting worse and your doctor might need to give you another medicine.
- People with severe asthma should have regular blood tests to monitor the amount of potassium in their blood. This is because low oxygen levels in the blood (hypoxia) and various asthma medicines, including this one, can lower blood potassium levels.
Use with caution in
- Elderly people
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Heart failure
- Irregular heart beats (arrhythmias)
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Very high blood pressure
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Hyperthyroidism
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Peptic ulcer
- Liver disease
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Chronic alcoholism
- Viral infections
Not to be used in
- Allergy to xanthines, eg theophylline, caffeine
- Life long inherited blood diseases which can cause a variety of symptoms, including mental health problems (porphyrias)
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History of fits (seizures), eg epilepsy.
- Amnivent SR tablets are not recommended for children.
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 during pregnancy has not been established, Its use during the third trimester may be associated with irritability in the baby. This medicine should only be used during pregnancy when the benefits outweigh any possible risks to the foetus. Seek medical advice from your doctor.
- This medicine passes into breast milk and has been associated with irritability in the breast fed infant. Seek medical advice from your doctor before breastfeeding while using this medicine.
Label warnings
- This medication is to be swallowed whole, not chewed.
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