Health Centres - Nitro-Dur patches (glyceryl trinitrate)
How does it work?
Nitro-Dur patches contain the active ingredient glyceryl trinitrate, which is a type of medicine called a nitrate. It is used to help the heart work more easily.
Glyceryl trinitrate works by being converted in the body to a chemical called nitric oxide. This chemical is made naturally by the body and has the effect of making the veins and arteries relax and widen (dilate). When the blood vessels dilate in this way there is more space inside them and hence less resistance. This makes it easier for the heart to pump blood around the body.
Widening the veins also decreases the volume of blood that returns to the heart with each heartbeat. This makes it easier for the heart to pump that blood out again.
As a result of both these actions, the heart does not need as much energy to pump the blood around the body and therefore needs less oxygen.
Glyceryl trinitrate also widens the arteries within the heart itself, which increases the blood and oxygen supply to the heart muscle.
The pain of angina is caused by too little oxygen reaching the heart when its workload increases, such as during exercise. Glyceryl trinitrate improves the oxygen supply to the heart, as well as decreasing the amount of oxygen that the heart needs by making it easier for the heart to pump blood around the body. It can therefore be used to treat angina.
Nitro-Dur patches are used on a regular basis to help prevent angina attacks. The medicine is absorbed continuously from the patch through the skin and into the bloodstream.
Glyceryl trinitrate is also available as short-acting sublingual tablets and sprays, which are administered under the tongue if needed to give rapid relief from angina attacks. See the factsheets linked at the end of this article for more information.
What is it used for?
- Preventing angina attacks.
How do I use the patches?
- With long-term continuous use the body can start to become tolerant to this medicine. To avoid this problem it is important that you have a period of between 8 and 12 hours every day when you are not wearing a patch. This is usually acheived by removing the patch at night, but ask your doctor or pharmacist for advice on when is best for your patch-free interval.
- When you put on a new patch (usually in the morning) this replacement patch should be applied to a different area of skin from the area you last used. Wait several days before applying a fresh patch to the same area of skin.
- Dispose of the old patch carefully, out of the reach of children, as it may still contain some active medicine.
- If you think that your patches have becomes less effective at preventing angina attacks you should consult your doctor or pharmacist.
- You should not suddenly stop using the patches, as this could cause your angina to get worse. If treatment with the patches is stopped, this should be done gradually, following the instructions given by your doctor.
Warning!
- This medicine should not be used to treat an angina attack, as it does not work quickly enough. It should be used regularly, as prescribed, to prevent angina attacks, and you should keep your glyceryl trinitrate (GTN) sublingual tablets or spray with you at all times to use if you do have an angina attack.
- This medicine may cause dizziness and so may affect 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.
- Drinking alcohol may enhance some of the side effects of this medicine, such as feeling faint or dizzy.
- Nitro-Dur patches should be removed before attempting defibrillation or cardioversion and before diathermy.
Use with caution in
- Severely decreased kidney function.
- Severely decreased liver function.
- People who have recently had a heart attack.
-
Underactive thyroid gland .
- People with low levels of oxygen in their blood, eg due to lung disease.
- Dangerously low body temperature (hypothermia).
- Malnutrition.
Not to be used in
- Allergy to nitrates.
- Low blood pressure (hypotension).
- Low volume of circulating blood (hypovolaemia).
- Inflammation of the sac surrounding the heart that stops the heart from beating properly (constrictive pericarditis).
- Fluid in the sac surrounding the heart that prevents the heart beating properly (cardiac tamponade).
- Narrowing of the main artery coming from the heart (aortic stenosis).
-
Narrowing of one of the valves in the heart.
- Heart disease in which the muscle of the heart grows abnormally (hypertrophic obstructive cardiomyopathy).
- Head injury.
- Bleeding in the brain (cerebral haemorrhage).
- Severe anaemia.
-
Closed angle glaucoma.
- This medicine is not recommended for use in 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 for use during pregnancy has not been established. It should only be used during pregnancy if the benefits to the mother outweigh any risks to the developing baby. Seek medical advice from your doctor.
- It is not known if this medicine passes into breast milk. It should only be used by breastfeeding mothers if the benefits to the mother outweigh any risks to the nursing infant. Seek medical advice from your doctor.
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