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Generic Name: isosorbide mononitrate
Product Name: Imdur

Indication: What Imdur is used for

Imdur is used to prevent angina. Angina is a pain or uncomfortable feeling in the chest, often spreading to the arms or the neck and sometimes to the shoulders and back. This is caused by too little blood and oxygen getting to the heart. The pain of angina is usually brought on by exercise or stress.

Your doctor will have explained why you are being treated with Imdur and told you what dose to take.

Follow all directions given to you by your doctor carefully. They may differ from the information contained here.

However, your doctor may prescribe this medicine for another use. Ask your doctor if you want more information.

Imdur is not addictive.

Action: How Imdur works

Imdur belongs to a group of medicines called nitrates.

Imdur works by relaxing the blood vessels, letting more blood and oxygen reach the heart.

Isosorbide mononitrate is an active metabolite of isosorbide dinitrate and exerts qualitatively similar effects. Isosorbide mononitrate reduces the workload of the heart by producing venous and arterial dilatation. By reducing the end diastolic pressure and volume, isosorbide mononitrate lowers the intramural pressure, hence leading to an improvement in the subendocardial blood flow. The net effect when administering isosorbide mononitrate is, therefore, a reduced workload for the heart and an improvement in the oxygen supply/demand balance of the myocardium.

Nitrates are highly effective in the prophylaxis of symptomatic and asymptomatic myocardial ischaemia. Nitrates dilate coronary arteries not only in pre- and post-stenotic vessels, but also in eccentric lesions. The natural initiator of vascular relaxation is thought to be endothelium-derived relaxing factor (EDRF), which has both the clinical and biological characteristics of nitric oxide (NO). Organic nitrates are metabolised to NO in the muscle cell via a sulfhydryl dependent mechanism. They are therefore thought to be the physiological substitute for EDRF.

Each Imdur tablet contains isosorbide mononitrate 60mg or 120mg as the active ingredient, plus, aluminium silicate, paraffin special, magnesium stearate, hydroxypropyl cellulose, and colloidal silica.

The coating on each tablet contains hydroxypropylmethylcellulose (E464), propylene glycol (E1520); with colouring agents, titanium dioxide (E171) iron oxide yellow (E172).

Dose advice: How to use Imdur

Before you use Imdur

When you must not use it

Do not use Imdur if you are allergic to it or food containing nitrates or nitrites or any ingredients listed here.

Do not use Imdur if you have the following medical conditions:

  • Low blood pressure;
  • Shock including those caused by low blood pressure or failing heart;
  • Pericarditis (swelling around the heart);
  • Weakened muscle of the heart.

You must not use Imdur whilst taking sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis).

Do not use Imdur if you are pregnant or breastfeeding unless your doctor says it is safe. Ask your doctor about the risks and benefits involved. We do not know if it is safe for you to take it while you are pregnant. It may affect your baby

It is not known if your baby can take in Imdur from breast milk if you are breastfeeding.

Do not give Imdur to children. There is no specific information about use in children, so Imdur is not recommended for use in children. Always ask your doctor before giving medicines to children.

Do not use after the use by (expiry) date printed on the pack or if the packaging is torn or shows signs of tampering. If it has expired or is damaged, return it to your pharmacist for disposal.

If you are not sure whether you should take this medicine, talk to your doctor.

Before you start to use it

You must tell your doctor if:

  • You have any allergies to any medicine, foods, preservatives or dyes. If you have an allergic reaction you may get a skin rash, hayfever, asthma or feel faint.
  • You have any of these medical conditions:
    • Any illness affecting your liver or kidneys;
    • Low blood pressure (this can make you feel faint, weak or dizzy, especially when you stand up suddenly);
    • Heart and blood vessel problems.

It may not be safe for you to take Imdur if you have any of these conditions.

Do not use Imdur to treat acute angina.

Imdur must be taken once daily.

Do not stop taking it abruptly.

Taking other medicines

Tell your doctor if you are taking any other medicines, including:

  • Sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis);
  • Medicines that you buy without a prescription from a pharmacy, supermarket or health food shop.

These medicines may affect the way Imdur works. Your doctor or pharmacist can tell you what to do if you are taking any other medicines.

If you have not told your doctor about any of these things, tell them before you take any Imdur.

Using Imdur

How to take it

Take one Imdur tablet every day, at about the same time. If your doctor tells you to take two 60 mg Imdur tablets each day, take both tablets at the same time.

Taking Imdur tablets at 24-hour intervals makes sure they keep working properly.

Swallow Imdur tablets whole, with half a glass of water or other liquid e.g. fruit juice, milk. Do not chew or crush the tablets.

The 60mg tablet can be broken in half if care is taken not to crumble them.

Imdur tablets are designed to let the drug out over a number of hours. If they are crushed or chewed they won’t work properly.

Imdur tablets are composed of a waxy substance that does not dissolve in the body. You may find the outer shell of the tablets in your bowel motions. The medication in them has already been absorbed by the body.

If you forget to take it

If you forget to take a dose, take it as soon as you remember, as long as it is not more than 8 hours late. If it is more than eight hours after you should have taken Imdur, wait until the right time the next day to take it.

Do not double the dose.

You may find that you will need to use the tablets or spray that your doctor has given you to use during angina attacks if you miss a dose of Imdur.

If you have trouble remembering when to take your medicine, ask your pharmacist for some hints.


Telephone your doctor or the Poisons Information Centre (13 11 26), or go to casualty at your nearest hospital immediately if you think that you or anyone else may have taken too much Imdur even if there are no signs of discomfort or poisoning.

If you take too many Imdur tablets you will have a pulsing headache. You may also feel excited, flushed, have cold sweats, nausea (feeling sick) and vomit.

While you are using Imdur

Things you must do

Take Imdur regularly once every day. If you don’t you will be more likely to get attacks of angina.

Tell your doctor if you continue to get angina attacks, or they become more frequent, while you are taking Imdur.

Things you must not do

Do not use Imdur to relieve acute attacks of angina. Your doctor will have given you other tablets or a spray to use when you get attacks of angina.

Do not take medicines known as phosphodiesterase type 5 (PDE5) inhibitors used to treat impotence (or erectile dysfunction) whilst on Imdur.

Do not stop taking Imdur unless you have discussed it with your doctor.

Do not use Imdur for any other complaints unless your doctor tells you to.

Do not give your medicine to anyone else, even if you have the same condition as you.

Things to be careful of

You will probably feel better when you start taking Imdur but be careful not to overdo physical activities straight away. You will need time to improve your physical fitness.

Be careful driving or operating machinery until you know how Imdur affects you. Imdur may cause dizziness and fainting in some patients, especially when you first start to take it. Make sure you know how you feel when you are taking Imdur before you drive a car, operate machinery, or do anything else that could be dangerous if you are dizzy.

Be careful when drinking alcohol while you are using Imdur. If you drink alcohol while you are taking Imdur, your blood pressure may drop, making you feel dizzy or faint.

Please talk to your doctor or pharmacist about these possibilities if you think they may bother you.

After using it


Keep your Imdur tablets in the blister pack until it is time to take them. If you take Imdur out of the blister pack it will not keep well.

Keep it in a cool dry place where the temperature stays below 30 degrees C. Do not store it or any other medicine in the bathroom or near a sink. Heat and dampness can destroy some medicines.

Keep it where young children cannot reach it. A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.

Do not leave it in the car on hot days.


Ask your pharmacist what to do with any tablets you have left over if your doctor tells you to stop taking them, or you find that they have expired.

Schedule of Imdur

Imdur Durules is an (S4) prescription only medicine.

Side effects of Imdur

Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking Imdur. Imdur helps most people with angina, but it may have unwanted side effects in a few people. All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor if you notice any of the following and they worry you:

  • Headache;
  • Feeling faint;
  • Dizziness;
  • Fatigue;
  • Muscle tenderness or weakness, not caused by exercise.

Headache is the most common side effect while taking Imdur. It can occur at the beginning of treatment, but usually goes away after a few days.

These are all mild side effects of Imdur.

Tell your doctor if you notice anything else that is making you feel unwell. Some people may get other side effects while taking Imdur.

For further information talk to your doctor.


  1. Imdur Consumer Medicine Information (CMI). North Ryde, NSW: AstraZeneca Pty Ltd. December 2005. [PDF]
  2. Imdur Durules Product Information (PI). North Ryde, NSW: AstraZeneca Pty Ltd. May 2006. [PDF]


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Posted On: 22 July, 2003
Modified On: 12 April, 2018
Reviewed On: 12 April, 2018


Created by: myVMC