Nitroglycerin brands and prices in Pakistan

About Nitroglycerin (glyceryl trinitrate, GTN)

Nitroglycerin, also called glyceryl trinitrate or GTN, is a medicine from a group called nitrates. It relaxes and widens blood vessels. This lets more blood and oxygen reach the heart and makes the heart's work easier, which eases chest pain from angina. It comes as tablets that dissolve under the tongue, a spray used under the tongue, and skin patches. There is also an ointment for the bottom, and a drip given in hospital.

Who should not take it, or should take care

• Do not use it if you are allergic to glyceryl trinitrate or any of the other ingredients.
• Do not use it if you take erection medicines such as sildenafil, tadalafil, vardenafil or avanafil, or riociguat. Together they can make blood pressure drop dangerously. If angina starts after taking an erection medicine, stop and rest, do not use GTN, and get emergency help if the pain does not go.
• Do not use it if you have very low blood pressure or shock, severe anaemia, a very slow heartbeat, or circulatory collapse.
• Do not use it if you have had a recent head injury or bleeding in the brain.
• Do not use it if you have narrowed heart valves or arteries, angina caused by a heart muscle disease, or constrictive pericarditis (a stiff lining around the heart).
• Tell your doctor if you have had a stroke, a recent heart attack, heart failure, or raised pressure inside the head.
• Tell your doctor if you have glaucoma, liver or kidney problems, an underactive thyroid, or problems controlling your blood pressure.
• Pregnancy: ask your doctor for advice if you are pregnant or might be.
• Breastfeeding: the UK and Irish spray leaflets say not to use it while breastfeeding. Ask your doctor.
• Tell the medical team that you use GTN before any operation, dental work or test. You may be asked to stop it for a short time before surgery. Also tell staff if you wear a GTN patch before an MRI scan or electrical heart treatment.

Medicines and drinks that can interact

• Erection medicines (sildenafil, tadalafil, vardenafil, avanafil) and alprostadil: do not combine with GTN
• Riociguat: do not combine with GTN
• Other medicines for blood pressure or the heart, including beta-blockers, calcium channel blockers, water tablets (diuretics) and other nitrates, which can make blood pressure drop too far
• Heparin (a blood thinner)
• Tricyclic antidepressants, antipsychotics and other mental health medicines
• Migraine medicines containing ergot (ergotamine or dihydroergotamine)
• Apomorphine (for Parkinson's disease)
• Aspirin (tell your doctor before starting GTN)
• Medicines that cause a dry mouth, such as some antidepressants, antihistamines, cold medicines and bladder medicines. They can stop the tablets dissolving well, so a doctor may suggest the spray instead.
• Anti-inflammatory painkillers such as ibuprofen and naproxen should not be taken regularly, as they may make angina worse. Paracetamol is fine; ask a pharmacist before taking stronger painkillers.
• Herbal remedies and supplements: there is not enough information to say they are safe, so tell your pharmacist.

Always tell your doctor and pharmacist about every medicine, supplement and herbal product you take.

Using it safely

• Always carry your tablets or spray with you, and keep a spare pack so you do not run out. It is hard to tell how much is left in a spray.
• Learn how to use your spray or tablets before you need them, as an attack can come on suddenly.
• Sit down before using it. Put the tablet under your tongue and let it dissolve; do not chew or swallow it. For the spray, spray under your tongue, do not breathe it in, and close your mouth.
• Rest afterwards and stand up slowly, because you may feel faint.
• Your doctor will tell you how many doses you can use for one attack and when to call for help. Follow this exactly.
• Keep tablets in their original bottle with the lid closed tightly, because the medicine can escape into the air. Opened bottles go out of date, so check the leaflet and replace them in time.
• The spray is under pressure: do not use it near a flame or a lit cigarette, and do not pierce or burn the can.
• Patches: put them on clean, dry, hairless skin and change the place each time. Your doctor will tell you when to put the patch on and take it off. A regular patch-free break is needed, or the medicine can stop working well.
• Do not suddenly stop patches or regular GTN without talking to your doctor, as angina may get worse.
• Keep alcohol low. It can make dizziness and fainting more likely.
• Do not drive, cycle or use machines if you feel dizzy, sleepy or faint.

Common questions

How does GTN work?
It widens your blood vessels. More blood and oxygen reach the heart muscle, and the heart does not have to work as hard, so the chest pain eases.

Why do I get a headache?
Headache is the most common side effect, because GTN widens blood vessels. It often gets better as you keep using it. Rest, drink fluids and ask a pharmacist about paracetamol. See a doctor if headaches are severe or do not settle.

Can I use GTN with erection medicines?
No. Using GTN with sildenafil, tadalafil, vardenafil or avanafil can make your blood pressure fall dangerously low. If you get angina after taking one of these, stop, rest and do not use GTN. Call an ambulance if the pain does not go.

Can I drink alcohol?
Alcohol makes the blood-pressure-lowering effect of GTN stronger, which can make you dizzy or faint. NHS advice is to avoid alcohol if it affects you this way, and not to drink much even if it does not.

Will GTN affect my contraception?
No, GTN does not affect any kind of contraception. But the combined pill is not usually recommended for people with angina, so talk to your doctor about the best choice.

Prepared from the sources listed by the MedInfoBase team. General information, not medical advice: it gives no doses. Your doctor or pharmacist decides the medicine and dose for you.