Glyceryl trinitrate
Also known as: GTN, nitroglycerin, GTN spray
A fast-acting nitrate spray or tablet under the tongue that widens veins and coronary arteries to relieve an angina attack within minutes.
- Generic name
- Glyceryl trinitrate
- Active ingredient
- Glyceryl trinitrate
- Product type
- Small-molecule medicine
- Drug class
- Nitrates
- Brand names
- UK Glytrin, Nitrolingual · US Nitrostat, Nitro-Dur
- Routes
- Sublingual, Buccal, Transdermal, Intravenous
- Dosage forms
- Spray, Tablet, Patch, Infusion
- Also known as
- GTN, nitroglycerin, GTN spray
- Forms
- Sublingual spray 400 micrograms per dose or tablets; patches; intravenous infusion; modified-release tablets (isosorbide)
- Onset and duration
- Sublingual within 1-3 minutes, lasting 20-30 minutes.
- Terminology
- RxNorm RxCUI 4917 · ATC C01DA02 · FDA EPC Nitrate Vasodilator [EPC]
- Monitoring
- Blood pressure during infusions; frequency of spray use is a marker of angina control.
Availability by country
| Country | Status | Note | Source |
|---|---|---|---|
| UK | Pharmacy or behind the counter | Sublingual spray and tablets are pharmacy (P) medicines | UK |
| UK | Prescription only | Patches, buccal tablets and infusions | UK |
| US | Prescription only | US |
Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.
What it is used for
- Relieving an angina attack within minutes (spray or tablet under the tongue)
- Preventing angina before exertion
- Intravenous infusion for unstable angina, heart attack with ongoing pain and acute heart failure
- Long-acting isosorbide mononitrate for regular angina prevention; GTN ointment for anal fissures
How it works in the body
Releases nitric oxide in vascular smooth muscle, activating guanylate cyclase and relaxing the vessel. Veins dilate most, so less blood returns to the heart and it has less to pump against (lower preload and wall tension, lower oxygen demand); coronary arteries and collaterals widen, improving supply to ischaemic muscle. Relief within one to three minutes helps confirm that chest pain was angina, though oesophageal spasm responds too.
Common side effects
- Throbbing headache (from dilated scalp vessels), flushing
- Dizziness and faintness from a drop in blood pressure: sit down before using
Serious: seek help
- Severe hypotension and collapse if combined with sildenafil or similar drugs (contraindicated within 24-48 hours)
- Fast heart rate; rarely worsening of angina; methaemoglobinaemia with prolonged infusion
Cautions and interactions
- Tolerance develops with continuous exposure: long-acting nitrates need a nitrate-free interval each day
- If pain persists 5 minutes after a second dose, call emergency services: it may be a heart attack
- Severe aortic stenosis, hypertrophic cardiomyopathy, very low blood pressure, raised intracranial pressure
- Tablets lose potency after 8 weeks once opened; sprays last longer
Interactions
Check interactions
Taking Glyceryl trinitrate with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".
Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.
No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.
Same-class and related medicines
Same class: Nitrates
Medicines that share the class of Glyceryl trinitrate. They are separate medicines with their own licences, doses and interactions, not alternative names for Glyceryl trinitrate.
Related medicines
Medicines often discussed alongside Glyceryl trinitrate: used together, compared with it, or acting on the same problem by a different route.