Imdur (Isosorbide Mononitrate)
Complete patient guide for uses, dosage, side effects, and safety information
Prescription RequiredQuick Facts
What Is Imdur Used For?
Imdur contains isosorbide mononitrate and belongs to a group of medicines called nitrates. It is specifically designed to prevent angina attacks before they occur.
Primary Uses
Imdur is used to prevent angina, which is chest pain or discomfort that often spreads to the arms, neck, shoulders, or back. This pain happens when your heart doesn’t get enough blood and oxygen, usually triggered by exercise or stress.
How It Works
Imdur works by relaxing your blood vessels, allowing more blood and oxygen to reach your heart. This helps prevent the chest pain associated with angina attacks.
Important: Do not use Imdur to treat sudden angina attacks – your doctor will provide other medications for acute episodes
How to Take Imdur
Imdur modified release tablets are designed to release medication slowly over many hours, so proper administration is crucial for effectiveness.
Dosage Instructions
Take one Imdur modified release tablet every day at about the same time. If your doctor prescribes two 60mg tablets daily, take both at the same time. Swallow tablets whole with half a glass of water, fruit juice, or milk. Do not chew or crush the tablets. The 60mg tablet can be broken in half if done carefully without crumbling. Taking tablets at 24-hour intervals ensures they work properly.
What If You Miss a Dose?
If you forget a dose, take it as soon as you remember, but only if it’s less than 8 hours late. If more than 8 hours have passed, wait until your next scheduled dose the following day. You may need to use your emergency angina medication if you miss a dose.
Important: Never double the dose if you miss one. You may see the outer shell of the tablet in your bowel movements – this is normal as the medication has already been absorbed
Available Tablet Strengths
Side Effects
Like all medications, this medicine can cause side effects. Most are mild and temporary, but some require medical attention.
Common Side Effects
These side effects occur relatively frequently and usually don’t require emergency care:
- Headache (most common)
- Feeling faint
- Dizziness
- Fatigue
- Muscle tenderness or weakness
- Low blood pressure
- Fast heart rate
- Vertigo
- Poor appetite
- Nausea
- Vomiting
- Diarrhea
- Heartburn
- Skin rash
- Itching
Seek immediate medical attention if you experience:
- Continuing or more frequent angina attacks while taking Imdur
- Severe dizziness or fainting
- Signs of overdose: severe pulsing headache, excitement, flushing, cold sweats, nausea, vomiting
Important Warnings
Several serious conditions and medications make Imdur unsafe to use. Always inform your healthcare providers about your medical history.
Who Should Not Take Imdur
Do not use Imdur if you are allergic to isosorbide mononitrate, nitrates, nitrites, or any ingredients in the medication. Also avoid if you have low blood pressure, shock (including from low blood pressure or heart failure), pericarditis (heart inflammation), weakened heart muscle, or if you take sildenafil (Viagra), vardenafil (Levitra), or tadalafil (Cialis).
Medical Conditions to Discuss
Tell your doctor if you have allergies to medicines, foods, preservatives, or dyes; liver or kidney disease; low blood pressure that causes faintness, weakness, or dizziness when standing; or any heart and blood vessel problems. These conditions may make Imdur unsafe for you.
Pregnancy and Breastfeeding
Do not use Imdur during pregnancy or breastfeeding unless your doctor determines it’s safe. It’s unknown whether Imdur affects unborn babies or passes into breast milk. Discuss risks and benefits with your doctor if you’re pregnant, planning pregnancy, or breastfeeding.
Children: Do not give Imdur to children – it is not recommended for pediatric use
Drug Interactions
Some medications can cause dangerous interactions with Imdur, potentially leading to serious side effects.
Erectile Dysfunction Medications: Never take erectile dysfunction medications while using Imdur – this combination can be life-threatening
- Phosphodiesterase inhibitors (sildenafil/Viagra, vardenafil/Levitra, tadalafil/Cialis) – can cause serious side effects including fainting or heart attack
- Calcium antagonists – can cause dangerous drops in blood pressure when standing
Alcohol & Driving
Imdur can affect your ability to drive safely and may interact dangerously with alcohol, causing additional safety concerns.
Alcohol
Be very careful when drinking alcohol while taking Imdur. Alcohol can cause your blood pressure to drop further, making you feel dizzy or faint. Tell your doctor about your alcohol consumption habits.
Driving and Operating Machinery
Be careful driving or operating machinery until you know how Imdur affects you. The medication may cause dizziness and fainting, especially when you first start taking it. Make sure you know how you feel before driving or doing anything that could be dangerous if you’re dizzy.
Storage
Keep Imdur modified release tablets in their original blister pack until you’re ready to take them – removing them early will affect how well they keep. Store in a cool, dry place where temperature stays below 30°C (86°F). Keep away from moisture, heat, and sunlight. Don’t store in bathrooms, near sinks, in cars, or on window sills. Keep out of reach of children.
Overdose Information
If you take too many Imdur tablets, you may experience a severe pulsing headache, feel excited or flushed, have cold sweats, nausea, and vomiting. Seek immediate medical attention by calling the Poisons Information Centre (13 11 26), contacting your doctor, or going to the nearest hospital emergency department, even if you don’t feel unwell yet.
Frequently Asked Questions
Yes, you can take Imdur with half a glass of water, fruit juice, or milk. The medication can be taken with or without food.
Take the missed dose as soon as you remember, but only if it’s less than 8 hours late. If more than 8 hours have passed, skip the missed dose and take your next dose at the regular time. Never double the dose.
Be very careful with alcohol while taking Imdur. Alcohol can cause your blood pressure to drop further, making you feel dizzy or faint. Always discuss your alcohol consumption with your doctor.
Do not stop taking Imdur suddenly without discussing it with your doctor. Stopping abruptly may increase your risk of angina attacks.
This is completely normal. Imdur tablets are made with a waxy substance that doesn’t dissolve in your body. The outer shell passes through while the medication has already been absorbed.
Do not crush or chew Imdur tablets as this will prevent them from working properly. The 60mg tablet can be broken in half if done carefully without crumbling, but swallow the pieces whole.
Imdur is designed to prevent angina attacks rather than treat them when they occur. It works continuously when taken regularly once daily. Your doctor will provide other medications for treating acute angina attacks.
Important Disclaimer
This information is intended for general educational purposes only and should not be considered medical advice. Always consult your healthcare provider or pharmacist before starting, stopping, or changing any medication.
If you think you may have a medical emergency, call your doctor or emergency services immediately.