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Isosorbide Mononitrate

Last updated on 06/07/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Isosorbide Mononitrate


BRAND NAME(S) IN HONG KONG: Elantan, Imdur, Durules

DRUG CLASS: Antianginal agents

SUB CLASS: Nitrates

USED FOR: Prevention and treatment of angina 

– 40mg, 60mg (extended-release tablets)
– 20mg (tablets)

What is Isosorbide Mononitrate for?

Isosorbide Mononitrate belongs to a class of medications called nitrates. It produces a vasodilator effect on the peripheral veins and arteries and relaxes vascular smooth muscle to increase oxygen supply to the heart. Isosorbide Mononitrate is therefore used to prevent and treat angina.

How to use it?

Isosorbide Mononitrate can be taken orally as conventional tablets or extended-release tablets. They should be taken on an empty stomach.

For conventional tablets, start with 20 mg twice daily with the 2 doses given 7 hours apart.

For extended-release tablets, take 30-60 mg once daily in the morning. You may increase the dose to 120 mg once daily after several days if tolerated. Swallow the extended-release tablets whole. Do not crush or chew it.

What are the side effects of Isosorbide Mononitrate?

Common side effects of Isosorbide Mononitrate include nausea, headache, dizziness, angina, bradycardia, and shortness of breath.

Who should not take Isosorbide Mononitrate?

– People who are allergic to Isosorbide Mononitrate or any component of the formulation
– People who are taking riociguat, or medicines for erectile dysfunction (e.g. Avanafil, Sildenafil, Tadalafil, Vardenafil)

Pharmacist Tips:

– Only the immediate-release tablets can be used as the treatment of angina. However, the onset of action of oral isosorbide mononitrate is not sufficiently rapid for this medication to be useful in aborting an acute anginal episode. In the event of an angina attack, seek immediate medical attention.
– It is important to have a nitrate-free period (times when you are not taking this medication) to minimize tolerance. Consider the recommended dosing schedule below if possible. 

Common dosing schedule:
Isosorbide Mononitrate should be taken on an empty stomach, at least 30 minutes before or 2 hours after food.

For extended-release tablets once daily dosing, it is recommended to be administered in the morning upon rising with a glass of water.

For immediate-release tablets, consider to schedule the twice daily doses 7 hours apart, for example administering at 8 am and 3 pm.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Isosorbide Mononitrate may interact with:
– Riociguat
– Phosphodiesterase inhibitors, e.g. Sildenafil, Tadalafil, Vardenafil, Avanafil

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Isosorbide Mononitrate in Hong Kong?

In Hong Kong, Isosorbide Mononitrate is a medicine under supervised sales and can be purchased under the supervision of a pharmacist from any pharmacies in Hong Kong. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Isosorbide Mononitrate in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.