Monodur (Isosorbide Mononitrate)
Complete patient guide for uses, dosage, side effects, and safety information
Prescription RequiredQuick Facts
What Is Monodur Used For?
Monodur 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
Monodur is used to prevent angina, which is a pain or uncomfortable feeling in the chest that often spreads to the arms, neck, shoulders, or back. This pain is caused by too little blood and oxygen getting to the heart, usually brought on by exercise or stress.
How It Works
Monodur works by relaxing the blood vessels, allowing more blood and oxygen to reach the heart. This helps prevent angina attacks from occurring.
Important: Do not use Monodur to treat acute angina attacks – your doctor will provide other medications for immediate relief during attacks
How to Take Monodur
Monodur modified release tablets are designed to release medication slowly over many hours and must be taken exactly as prescribed to work properly.
Dosage Instructions
Take one Monodur modified release tablet every day at about the same time. If your doctor prescribes two 60mg tablets daily, take both tablets at the same time. Swallow tablets whole with half a glass of water or other liquid (fruit juice, milk). Do not chew or crush the tablets. The 60mg tablet can be broken in half if done carefully without crumbling. Take at 24-hour intervals to ensure proper effectiveness.
What If You Miss a Dose?
If you forget a dose, take it as soon as you remember, but only if it’s not more than 8 hours late. If it’s more than 8 hours after your scheduled time, wait until the next day’s regular time to take it. You may need to use your emergency angina medication if you miss a dose.
Important: Never double the dose if you miss one. The modified release tablets contain a waxy substance that doesn’t dissolve – you may see the outer shell in your bowel movements, but 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
- Poor appetite
- Nausea
- Vomiting
- Diarrhea
- Heartburn
- Skin rash
- Itching (pruritus)
Seek immediate medical attention if you experience:
- Low blood pressure (hypotension)
- Fast heart rate (tachycardia)
- Fainting
- Continued or more frequent angina attacks
Important Warnings
Certain medical conditions and medications can make Monodur unsafe or require special monitoring during treatment.
Who Should Not Take Monodur
Do not use Monodur if you are allergic to isosorbide mononitrate, nitrates, nitrites, or any ingredients in the tablets. Also avoid if you have low blood pressure, shock (including from low blood pressure or heart failure), pericarditis (heart swelling), weakened heart muscle, or if you are taking 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 illness; low blood pressure that causes faintness, weakness or dizziness when standing; or heart and blood vessel problems. These conditions may make Monodur unsafe for you.
Pregnancy and Breastfeeding
Do not use Monodur if you are pregnant or breastfeeding unless your doctor says it is safe. It is not known if Monodur is safe during pregnancy or if it passes into breast milk. Discuss the risks and benefits with your doctor.
Serious Drug Interaction: Never take phosphodiesterase inhibitors (Viagra, Levitra, Cialis) while using Monodur as this can cause serious side effects including fainting or heart attack
Drug Interactions
Some medications can interfere with Monodur and affect how it works, potentially causing serious side effects.
- Phosphodiesterase inhibitors (sildenafil/Viagra, vardenafil/Levitra, tadalafil/Cialis) – can cause serious side effects like fainting or heart attack
- Calcium antagonists – can cause orthostatic hypotension (low blood pressure when standing)
Alcohol & Driving
Monodur can affect your ability to drive safely and may interact dangerously with alcohol, causing additional drops in blood pressure.
Alcohol
Be careful when drinking alcohol while using Monodur. Alcohol can cause your blood pressure to drop further, making you feel dizzy or faint. Tell your doctor about your alcohol consumption.
Driving and Operating Machinery
Be careful before driving or using machines until you know how Monodur affects you. Monodur may cause dizziness and fainting, especially when you first start taking it. Make sure you know how you feel before driving, operating machinery, or doing anything that could be dangerous if you are dizzy.
Storage
Keep Monodur modified release tablets in the blister pack until it’s time to take them, as they won’t keep well if removed early. Store in a cool, dry place where temperature stays below 30°C. Keep away from moisture, heat, and sunlight – do not store in bathrooms, near sinks, in cars, or on window sills. Keep out of reach of children. Take expired or unwanted medicine to any pharmacy for safe disposal.
Overdose Information
If you take too many Monodur tablets, you may experience a pulsing headache, feel excited or flushed, have cold sweats, nausea, and vomiting. Immediately phone the Poisons Information Centre (13 11 26), contact your doctor, or go to the nearest hospital Emergency Department, even if you feel fine.
Frequently Asked Questions
Monodur is a modified release tablet designed to prevent angina attacks over 24 hours. It works by gradually releasing medication throughout the day to keep your blood vessels relaxed and maintain good blood flow to your heart.
Yes, you can take Monodur with or without food. Swallow the tablet whole with half a glass of water or other liquid like fruit juice or milk.
Do not stop taking Monodur suddenly without discussing it with your doctor. Stopping abruptly may increase your risk of angina attacks returning.
Be careful when drinking alcohol while using Monodur. Alcohol can cause your blood pressure to drop further, making you feel dizzy or faint. Tell your doctor about your alcohol consumption.
If you forget a dose, take it as soon as you remember, but only if it’s not more than 8 hours late. If it’s more than 8 hours after your scheduled time, wait until the next day’s regular time. Never double the dose. You may need to use your emergency angina medication if you miss a dose.
Do not chew or crush Monodur tablets as they are designed to release medication slowly over many hours. The 60mg tablet can be broken in half if done carefully without crumbling, but swallow the pieces whole.
This is normal. Monodur tablets contain a waxy substance that doesn’t dissolve in your body. You may see the outer shell in your bowel movements, but the medication has already been absorbed by your body.
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.