- Isosorbide mononitrate helps prevent angina. It is not suitable to take to treat an angina attack. (Make sure you have glyceryl trinitrate (GTN) spray or tablets for if you get chest pain.)
- The most common side-effect is headache. This should soon pass.
About isosorbide mononitrate
|Type of medicine ||Nitrate |
|Used for ||Angina |
|Also called ||Chemydur® XL, Cibral® XL, Dynamin® XL, Elantan® LA, Eumon® XL, Imdur®, Isib® XL, Ismo®, Isodur® XL, Isotard® XL, Modisal® XL, Monigen® XL, Monomax®, Monomil® XL, Monosorb® XL, Relosorb® XL, Tardisc® XL, Trangina® XL, Xismox® XL, Zemon® XL |
|Available as ||Tablets, longer-acting tablets and capsules |
Isosorbide mononitrate helps prevent angina chest pain. Angina develops if part of your heart muscle does not get as much blood and oxygen as it needs. It is usually caused by narrowing of your coronary arteries due to a build-up of a fatty substance called atheroma. The narrowing makes it more difficult for blood to flow to your heart muscle.
Isosorbide mononitrate works in two ways. It relaxes blood vessels in your body (causing them to widen) and this reduces the strain on your heart, making it easier for your heart to pump blood. It also relaxes and widens the coronary arteries which increases the flow of blood to your heart muscle.
Before taking isosorbide mononitrate
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start isosorbide mononitrate it is important that your doctor or pharmacist knows:
- If you are pregnant, trying for a baby or breast-feeding.
- If you have problems with your liver or kidneys.
- If you have low blood pressure.
- If you have been told by a doctor you have anaemia (low levels of iron in your blood) or hypoxaemia (low levels of oxygen in your blood).
- If you have an underactive thyroid.
- If you have glaucoma (an increased pressure in your eye).
- If you have recently had a head injury or a heart attack.
- If you have ever had an allergic reaction to a medicine.
- If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines. It is particularly important that you tell your doctor if you are using any products to help treat erectile dysfunction (such as Viagra®).
How to take isosorbide mononitrate
- Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about the specific brand of isosorbide mononitrate you have been given, and a full list of side-effects which you may experience from taking it.
- Some tablets should be taken 2 or 3 times daily. Longer-acting tablets and capsules are taken once daily in the morning. (Longer-acting tablets and capsules have 'XL', 'SR', 'LA', or 'Retard' after the brand name.) Your doctor or pharmacist will tell you which is the right dose for you, and this will also be printed on the label of the pack to remind you.
- Swallow the tablet or capsule whole - do not chew or crush them before you swallow. This is because they are specially made to release the medicine they contain in a controlled way over the day. You can take them before or after meals.
- If you forget to take a dose, take it as soon as you remember. If you do not remember until the following day, skip the missed dose. Do not take two doses together to make up for a forgotten dose.
Getting the most from your treatment
- Isosorbide mononitrate tablets and capsules are not suitable to take to treat an angina attack. Your doctor will also prescribe glyceryl trinitrate (GTN) for you to take if this happens. If after using GTN your pain has not eased within a few minutes, call for an ambulance.
- Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress
- The longer you take isosorbide mononitrate, the more your body can get used to it, which sometimes means it has a lesser effect. If you are prescribed more than one dose a day, your doctor may advise that you have some time during each day without isosorbide mononitrate to avoid this. This means that the tablets may not be prescribed at equal intervals throughout the day. Follow carefully any instructions you have been given about when to take your doses.
- It is best not to drink alcohol while you are taking isosorbide mononitrate. Alcohol will increase the chance that you experience side-effects, such as feeling dizzy or light-headed. If you do drink alcohol, drink only a little and be aware of its effect on you.
- If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.
- If you buy any medicines, check with a pharmacist that they are suitable for you to take with isosorbide mononitrate.
Can isosorbide mononitrate cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.
|Common isosorbide mononitrate side-effects - these affect around 1 in 10 people who take this medicine ||What can I do if I experience this? |
|Headache ||Ask your doctor or pharmacist to recommend a suitable painkiller. This usually disappears after the first week or so |
|Feeling dizzy or weak ||Do not drive or use tools or machines |
|Feeling sick ||This should soon pass |
|Flushing ||If troublesome, speak with your doctor |
If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.
How to store isosorbide mononitrate
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.