Easy-to-read medicine information about isosorbide mononitrate – what is it, how to take it safely and possible side effects.
|Type of medicine||Also called|
What is isosorbide mononitrate?
Isosorbide mononitrate is used to prevent chest pain (also called angina). Angina happens when the blood supply to the muscles of your heart are restricted, due to narrowing of the blood vessels supplying the heart.
Isosorbide mononitrate works by widening blood vessels, letting more blood and oxygen reach the heart which reduces strain on your heart, making it easier for the heart to pump blood.
NOTE: isosorbide mononitrate will not treat chest pain (an angina attack) that has already started. Your doctor will give you a spray (GTN spray) to use if you have an attack of angina. Read more about angina and GTN spray.
Isosorbide mononitrate is also sometimes used together with other medicines for people with heart failure. This is a condition where there is a problem with the pumping action of the heart. Read more about heart failure.
In New Zealand isosorbide mononitrate is available as immediate-release tablets (20 mg) and slow release tablets (40 mg and 60 mg).
- The dose of isosorbide mononitrate will be different for different people, depending on what it is being used for.
- Your doctor will usually start you on a low dose and increase the dose depending on how you respond. This allows your body to get used to the medicine and reduces side effects.
- Always take your isosorbide mononitrate exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it and any special instructions.
- Isosorbide mononitrate tablets are available in different strengths. If your tablets look different to your last supply speak with your doctor or pharmacist for advice.
How to take isosorbide mononitrate
Isosorbide mononitrate tablets are available in 2 forms: immediate release tablets and slow release tablets.
|Formulation||How to take it|
|Immediate release tablets (20 mg)||
|Slow release tablets (40 mg and 60 mg)||
- Swallow your tablets with a glass of water.
- You can take isosorbide mononitrate with or without food.
- Limit alcohol intake while you are taking isosorbide mononitrate. Alcohol can increase your chance of side effects, such as dizziness and light-headedness.
- If you forget to take your dose, take it as soon as you remember. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
- Do not stop taking isosorbide mononitrate suddenly – this can make your angina worse.
|If your angina becomes more frequent or severe, lasts longer or happens when you are doing very little or resting, see your doctor.|
Precautions – before taking isosorbide mononitrate
- Are you pregnant, planning a pregnancy or breastfeeding?
- Do you have problems with your kidneys or liver?
- Do you have heart failure or have you recently had a heart attack?
- Do you have glaucoma?
- Do you have an underactive thyroid (hypothyroidism)?
- Are you are taking or using any other medicines? This includes any medicines you are using that are available to buy from a pharmacy, supermarket or natural health store without a prescription. It is particularly important that you tell your doctor or pharmacist if you are using any medicines to help treat erectile dysfunction.
If so, it’s important that you tell your doctor or pharmacist before you start taking isosorbide mononitrate. Sometimes a medicine isn’t suitable for a person with certain conditions or it can only be used with extra care.
|Do not take isosorbide mononitrate if you are taking medicines used to treat erection problems, such as:
Using erectile dysfunction medicine with isosorbide mononitrate can cause a sudden decrease in blood pressure, which can be life-threatening.
Possible side effects
Like all medicines, isosorbide mononitrate can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.
|Side effects||What should I do?|
- Isosorbide mononitrate may interact with a few medications and herbal supplements so check with your doctor or pharmacist before starting isosorbide mononitrate or before starting any new medicines.
- Isosorbide mononitrate interacts with medicines to treat erectile problems such as sildenafil (Viagra, Avigra, Vedafil, Silvasta), tadalafil (Cialis) and vardenafil (Levitra).
The following links have more information on isosorbide mononitrate.
Isosorbide mononitrate New Zealand Formulary Patient Information
- Isosorbide mononitrate New Zealand Formulary