glyceryl trinitrate at a glance
Medicine class
Organic nitrate and nitric-oxide donor.
Main roles
Angina treatment or prevention, chronic anal-fissure pain relief and specialist hospital cardiovascular care.
What is glyceryl trinitrate used for?
Licensed uses differ by formulation and product.
Under-the-tongue formulations: relief of angina symptoms.
Transdermal patches: prevention of angina or maintenance of peripheral intravenous-site patency.
Rectal ointment: relief of chronic anal-fissure pain in adults; it is not licensed to promote healing.
Intravenous infusion: specialist hospital management of selected severe ischaemic, cardiac, hypertensive or perioperative conditions.
How does glyceryl trinitrate work?
GTN generates nitric oxide, relaxing smooth muscle. Venous dilation reduces blood returning to the heart and lowers its workload and oxygen demand. In the anal canal, relaxing the internal sphincter reduces pressure and improves local blood flow, helping relieve fissure pain.
glyceryl trinitrate preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 1 mg/mL
Rectal ointment
Route: Rectal
Strengths: 4 mg/g
Transdermal patch
Route: Transdermal
Strengths: 5 mg/24 hours, 10 mg/24 hours
How to take glyceryl trinitrate
Use only the prescribed formulation and follow its leaflet because the routes are not interchangeable.
Sit down before using under-the-tongue GTN. Let tablets dissolve under the tongue without chewing or swallowing; spray under the tongue without inhaling.
Apply patches to clean, dry, healthy skin with little or no hair. Avoid creams or powders and rotate application sites.
Follow the supplied instructions for rectal ointment and wash your hands afterwards.
Intravenous GTN is administered by healthcare professionals with cardiovascular monitoring.
glyceryl trinitrate side effects
Common or expected effects
- Headache, sometimes severe
- Dizziness, weakness or sleepiness
- Flushing
- Nausea
- Low blood pressure, particularly on standing
- Skin irritation from patches
- Anal discomfort, itching or burning from rectal ointment
Get urgent medical advice
- Fainting or circulatory collapse
- Chest pain that is different from or worse than usual
- Markedly fast or slow heartbeat
- Breathing difficulty or blue or grey discolouration
- Severe allergic reaction with facial, mouth or throat swelling
glyceryl trinitrate in pregnancy
Human evidence is limited and advice differs by product. Angina in pregnancy requires obstetric and cardiology review; rectal ointment or intravenous treatment requires formulation-specific specialist assessment.
glyceryl trinitrate while breastfeeding
Evidence is limited and advice depends on the formulation. Rectal GTN is considered compatible with breastfeeding a healthy, full-term infant; wash hands after applying it. Systemic formulations require individual assessment, particularly for premature or unwell infants.
glyceryl trinitrate interactions
Tell the prescriber or pharmacist about all medicines, supplements and recreational substances.
PDE5 inhibitors: sildenafil, tadalafil and vardenafil
Contraindicated because the combination can cause severe hypotension.
Riociguat
Contraindicated with nitrates because substantial hypotension can occur.
Common questions about glyceryl trinitrate
Answers are fully visible for fast scanning and source review.
Are the spray, patches and ointment interchangeable?
No. They have different routes, absorption speeds and licensed purposes.
Can a patch stop sudden angina pain?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.