Isosorbide Dinitrate/Mononitrate

Please note: these are basic guidelines, refer to your doctor for a professional medical opinion.

Popular brand names:

[dinitrate] Isordil

[mononitrate] Elantan, Imdur, Ismo 20, Monicor SR

Drug group:

Nitrate vasodilator and anti-angina drug

Prescription needed?

Some preparations

What does it do?

• Isosorbide is mainly used to treat angina
• It is also sometimes used to treat heart failure

How does it work?

• Isosorbide dinitrate/mononitrate are nitrate vasodilators similar to glyceryl trinitrate
• Nitrates cause peripheral vasodilation (dilatation of the blood vessels especially veins)
• This results in pooling of blood in the veins, less blood returns to the heart, which reduces the work load and oxygen demand of the heart muscle

How should it be used?

• Isosorbide dinitrate/mononitrate can be stored for long periods without losing their effectiveness – unlike glyceryl trinitrate
• Drug-free periods are advised - to avoid reduced effectiveness with continuous daily use

What is the typical dosage?

Your doctor will recommend a dosage tailored to your need, but typically:

• Dinitrate: Tablets/SR tablets /spray/injection; Mononitrate: Tablets/SR tablets/SR capsules
• Relief of angina attacks: spray, 1–3 doses under the tongue as needed
• Prevention of angina: total 30–120mg daily, 2–4 x daily (tablets) or 1–2 x daily (SR)
• Heart failure: total 40–240mg daily, 2–4 x daily (tablets) or 1–2 x daily (SR)

How quickly will it start to work?

Spray: 2–3 minutes, SR tablets/capsules: 20–30 minutes 
              

How long will the effects last?

Tablets: 4–10 hours, SR tabs/caps: up to 17 hours, spray: 1–2 hours

When should I stop using it?

Do not stop the drug without consulting your doctor.   
                             

Is it safe for prolonged use?

The adverse effects may disappear with prolonged use, but the effects of the drug become weaker with continuous use.

What are the possible side effects?

The following have been reported:

• More common: headache, flushing
• Less common: dizziness/weakness (due to excessive drop in blood pressure)
• Report to your doctor before taking your next dose if you experience: fainting, palpitations

What other considerations are important?

Dosage may be adjusted by your doctor under certain conditions.

• Certain health problems: liver/kidney problems, blood disorders or anaemia, glaucoma, low blood pressure, heart attack, underactive thyroid, G6PD deficiency, recent head injury
• Other medicines: Sildenafil/tadalafil/vardenafil, antihypertensives
• Pregnancy and breast-feeding: Safety not established
• Children: Not usually prescribed
• Over 60: No special problems
• Driving and hazardous work: Caution, these drugs can cause dizziness
• Alcohol: Avoid, further lowering of blood pressure