[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Organic nitrates](https://durgical.com/en/pharmacology/classes/organic-nitrates/) › Isosorbide dinitrate

# 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.

Updated Nov 1, 2026

## Quick facts

**Group**
[Organic nitrates](https://durgical.com/en/pharmacology/classes/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.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## 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 →](https://durgical.com/en/conditions/stable-angina/)
- Heart failure with reduced ejection fraction, combined with hydralazine [Heart failure →](https://durgical.com/en/conditions/heart-failure/)

## Adverse effects

### Common

- Headache, which marks the drug's activity
- Lightheadedness on standing, worse with alcohol
- Flushing
- Reflex tachycardia

### Serious (rare, important)

- Severe hypotension and syncope
- Methaemoglobinaemia (rare)
- Rebound angina if stopped abruptly after long use

## 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

## Memory aid

Di-nitrate, two jobs: prevent angina, and with hydralazine help the failing heart, never to stop an 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.

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[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 3

- [Glyceryl trinitrate](https://durgical.com/en/pharmacology/glyceryl-trinitrate/)
- [Isosorbide mononitrate](https://durgical.com/en/pharmacology/isosorbide-mononitrate/)
- [Hydralazine](https://durgical.com/en/pharmacology/hydralazine/)

## Related conditions 2

- [Stable angina](https://durgical.com/en/conditions/stable-angina/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)

[← Back to the class: Organic nitrates](https://durgical.com/en/pharmacology/classes/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](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6df6a2fa-c56c-4eb6-a485-c16585420eb0) (DailyMed (U.S. National Library of Medicine), 2026); [Isosorbide: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682348.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C01DA08) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/isosorbide-dinitrate/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/isosorbide-dinitrate/