Isosorbide dinitrate
Organic nitrates
Organic nitrates
An oral nitrate that prevents angina attacks; it is too slow to stop an attack. With hydralazine it is also used in heart failure.
Quick facts
- Group
- Organic nitrates
- Target
- Soluble guanylate cyclase (activated by nitric oxide)
- Used for
- Heart failure
- Key effects
- Headache · Lightheadedness on standing · Flushing
- Monitor
- Blood pressure · Frequency of angina attacks
- ATC
- C01DA08
No doses: the clinician sets them by the current guideline.
Mechanism of action
Like other organic nitrates, isosorbide dinitrate releases nitric oxide, which activates soluble guanylate cyclase in vascular smooth muscle. cGMP rises and the muscle relaxes, mainly in veins: preload, wall tension and oxygen demand fall. Its active metabolite, isosorbide-5-mononitrate, carries much of the effect.
- Isosorbide dinitrate releases nitric oxide
- Guanylate cyclase makes more cGMP in smooth muscle
- Veins dilate: less preload and oxygen demand
Indications
- Prevention of angina pectoris due to coronary artery disease Stable angina →
- Heart failure with reduced ejection fraction, combined with hydralazine Heart failure →
Adverse effects
Common
- Headache, which marks the drug's activity
- Lightheadedness on standing, worse with alcohol
- Flushing
- Reflex tachycardia
Contraindications
- Use of PDE5 inhibitors (sildenafil, tadalafil, vardenafil)
- Use of riociguat
- Allergy to isosorbide dinitrate
Key interactions
- PDE5 inhibitors (sildenafil, tadalafil, vardenafil)
- Severe hypotension, syncope or ischaemia; contraindicated
- Riociguat
- Hypotension; contraindicated
- Alcohol and other vasodilators
- Additive hypotension
What is monitored
- Blood pressure, lying and standing
- Frequency of angina attacks
- Heart rate
Administration and safety
- The dosing schedule keeps a daily nitrate-free interval to prevent tolerance; doses are not added to fill it.
- Oral tablets do not stop an acute attack: sublingual glyceryl trinitrate is kept for that.
- Isosorbide dinitrate and isosorbide mononitrate have similar names but different products and schedules: the label is checked.
Pregnancy and breastfeeding
Human data are limited; it is used in pregnancy only when the benefit outweighs the risk.
Nursing care
- Check blood pressure before doses and watch for orthostatic dizziness.
- Ask about PDE5 inhibitors and riociguat before giving it.
- Teach the patient to rise slowly, limit alcohol and not stop it suddenly.
- Teach that headache is common early and usually fades; the schedule is not changed to avoid it.
Pharmacokinetics
- Absorption
- Almost complete by mouth, but bioavailability is low and very variable because of first-pass metabolism in the liver
- Metabolism
- Liver and other tissues, to active mononitrates (mainly isosorbide-5-mononitrate)
- Half-life
- About an hour for the parent drug; several hours for the 5-mononitrate
- Onset and duration
- Too slow by mouth to abort an acute attack
Test yourself
Think of the answer, then tap the question to see it.
Why is oral isosorbide dinitrate not used to stop an angina attack?
Its onset by mouth is too slow; sublingual glyceryl trinitrate is used for the acute attack.
Which drug is combined with isosorbide dinitrate in heart failure, and what does each add?
Hydralazine: it dilates arterioles (less afterload) while the nitrate dilates veins (less preload).
Why is the oral bioavailability of isosorbide dinitrate low and variable?
It undergoes extensive first-pass metabolism in the liver.
Connections
← Back to the class: Organic nitrates
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - ISOSORBIDE DINITRATE tablet (DailyMed (U.S. National Library of Medicine), 2026); Isosorbide: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.