Isosorbide Dinitrate

Isosorbide dinitrate is a nitrate medicine used mainly to prevent angina, which is chest pain caused by reduced blood flow to the heart. This guide covers isosorbide dinitrate uses, how it works, dosage, side effects, precautions, drug interactions, use in pregnancy and breastfeeding and its approximate price in India.

At a Glance

What is Isosorbide Dinitrate?

Isosorbide dinitrate is a nitrate medicine used mainly to prevent angina, which is chest pain caused by reduced blood flow to the heart muscle in coronary artery disease. It is a long-term preventive treatment and not a cure for heart disease. A fixed-dose combination of isosorbide dinitrate with hydralazine is used in some patients with heart failure. Isosorbide dinitrate should be used only under a doctor’s supervision.

How Isosorbide Dinitrate Works

Isosorbide dinitrate releases or is converted to nitric oxide, which relaxes the smooth muscle in blood vessel walls. It affects the veins more strongly than the arteries. Widening the veins (venodilation) reduces the amount of blood returning to the heart (preload), which lowers the heart’s workload and its oxygen demand. This helps prevent angina and can improve exercise tolerance. It relieves symptoms and does not treat the underlying narrowing of the coronary arteries.

When Isosorbide Dinitrate Is Used

• Angina prevention: The US label for immediate-release isosorbide dinitrate tablets covers prevention of angina pectoris due to coronary artery disease. These tablets are not a replacement for a fast-acting treatment for an acute attack.
• Heart failure (combination product only): The FDA-approved fixed-dose combination of isosorbide dinitrate and hydralazine (BiDil) is indicated as an add-on to standard therapy in self-identified Black patients with heart failure, to improve survival, prolong time to hospitalization for heart failure and improve patient-reported functional status. It is not for every patient with heart failure, and isosorbide dinitrate alone does not have this indication. The decision depends on the patient’s condition and other heart failure treatments and is made by the treating cardiologist. The combination does not act as a diuretic and does not remove excess fluid.
• Other uses: The benefit of oral isosorbide dinitrate in acute heart attack has not been established. Any other use is a decision for the treating cardiologist. Isosorbide dinitrate is not a treatment for high blood pressure.

Isosorbide Dinitrate Dosage and How to Take It

The dose depends on the form (immediate-release tablet, sublingual tablet, extended-release, spray or injection), the condition and your response. The dosing below applies only to immediate-release oral isosorbide dinitrate tablets, as given in US prescribing information. It is general information only, and it does not apply to sublingual tablets, sprays, extended-release forms or injections. Your doctor decides the dose.

• Immediate-release oral tablets (US labelling): The usual starting dose is 5 to 20 mg two or three times daily. For maintenance therapy, 10 to 40 mg two or three times daily is recommended.
• Nitrate-free interval (important): Continuous nitrate exposure can cause tolerance (loss of effect), so every dosing regimen must provide a daily dose-free interval. With immediate-release oral isosorbide dinitrate, the US label advises a daily dose-free interval of at least 14 hours. The exact schedule depends on the prescribed formulation and regimen, so do not assume that every formulation follows the same schedule. Take doses at the times your doctor has set, and do not add extra doses or make up your own gap.
• Sublingual tablets and sprays: Sublingual tablets and sprays are product-specific, faster-acting formulations. Use them exactly according to the product label and your doctor’s instructions. Their strength and dosing depend on the specific product and country. As an example, one spray product marketed in Switzerland is listed at 1.25 mg per spray, but other products differ, so this is not a universal spray dose.
• Injection: Injectable isosorbide dinitrate is a hospital product used under specialist supervision. It is separate from the oral forms, and no home dosing applies.
• Children: Safety and effectiveness in children have not been established, and isosorbide dinitrate is not typically used in children.
• Taking it: Swallow oral tablets with water. If you have chest pain, follow the rescue plan prescribed by your doctor, and do not simply take another dose of your regular tablet.

Take this medicine only as advised by your doctor. Do not change the dose or schedule on your own.

Side Effects of Isosorbide Dinitrate

Common effects may include:

• Headache, which is the most common effect and often improves with continued use
• Dizziness and lightheadedness, particularly when standing up
• Flushing (warmth or redness of the face and neck)
• Nausea

Serious effects need prompt medical attention:

• Severe low blood pressure (hypotension) and fainting (syncope): Severe hypotension can occur, even with relatively small doses, particularly when standing upright. Dizziness, weakness, fainting or collapse can occur. The risk is higher with other blood-pressure-lowering medicines, alcohol, dehydration or PDE5 inhibitors.
• Fast or pounding heartbeat (reflex tachycardia)
• Worsening angina: Low blood pressure from nitrates can sometimes be accompanied by increased angina.
• Severe allergic reactions: swelling of the face or throat, rash or breathing difficulty

If you get chest pain that is severe, lasts or does not go away, get emergency help.

Isosorbide Dinitrate Precautions and Monitoring

• Do not use if you are allergic to isosorbide dinitrate or any ingredient of your product.
• Never use with phosphodiesterase type 5 (PDE5) inhibitors (such as sildenafil, tadalafil or vardenafil) or with the medicine riociguat. The combination is contraindicated because it can cause a dangerous, potentially life-threatening fall in blood pressure. Tell any doctor treating you, including in an emergency, that you take a nitrate.
• Conditions that need caution or may rule out nitrates: Your doctor will decide, based on the product label, if you have low blood pressure or low blood volume (such as dehydration), a recent or acute heart attack (the benefit of oral isosorbide dinitrate in acute heart attack has not been established, and some labels contraindicate nitrates in certain acute heart attack situations), hypertrophic cardiomyopathy (nitrates may worsen angina in this condition), severe aortic or mitral valve narrowing, shock or circulatory collapse, or raised pressure inside the head (for example after a head injury or bleeding in the brain). Some conditions are contraindications in certain product labels and cautions in others, so ask your doctor.
• Stand up slowly, especially at the start of treatment or after a dose change, to avoid dizziness and fainting.
• Alcohol: Alcohol can increase the blood-pressure-lowering effect and the risk of dizziness and fainting, so avoid it or discuss it with your doctor.
• Do not stop suddenly without advice. Stopping prescribed anti-anginal therapy can allow angina symptoms to return. Follow your doctor’s plan, and do not change your schedule on your own.
• Monitoring: Your doctor may check your blood pressure and heart rate and review your symptoms regularly.

Isosorbide Dinitrate Drug Interactions

• PDE5 inhibitors (sildenafil, tadalafil, vardenafil) and riociguat: Combining them with nitrates can cause severe, potentially life-threatening low blood pressure.
• Other blood-pressure-lowering medicines (such as beta-blockers, calcium channel blockers, ACE inhibitors and diuretics) and alcohol: can add to the drop in blood pressure. These combinations are common in heart disease and are not prohibited, but your doctor may adjust doses and monitor you.
• Other nitrates (such as nitroglycerin): Use together only as part of a regimen prescribed by your doctor. Do not add or combine nitrate medicines on your own.

Tell your doctor and pharmacist about all prescription medicines, over-the-counter medicines and supplements you take. This list is not complete.

Isosorbide Dinitrate in Pregnancy and Breastfeeding

Human data on isosorbide dinitrate in pregnancy and breastfeeding are limited. Some product labels say its safety in pregnancy has not been established, and that nitrates may pass into breast milk, so it should be used only if the doctor decides the benefits outweigh the possible risks. If you are pregnant, planning pregnancy or breastfeeding, discuss treatment with your doctor. Do not stop a prescribed heart medicine on your own.

Isosorbide Dinitrate Brands, Strengths and Approximate Price in India

Examples of isosorbide dinitrate brands marketed in India include Sorbitrate (Abbott) and Isordil (Ipca), based on pharmacy listings. This is not an exhaustive list, and availability can change. Listings show 5 mg and 10 mg tablets, and sublingual and oral forms exist, so check which one you have been prescribed.

These are listing-based figures from an online pharmacy site, not guaranteed current MRPs. Prices for other strengths and brands are not listed here because current amounts could not be reliably verified. Prices vary by brand, strength, pack size, pharmacy, location, availability and date.

How HealthPil Can Help

Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional. If you have chest pain, angina or heart failure, or questions about your heart medicines, you can consult a doctor through HealthPil, including cardiologists who specialize in managing heart disease.