Glyceryl trinitrate (Percutol ointment)

How does it work?

Percutol ointment contains the active ingredient glyceryl trinitrate, which is a type of medicine called a nitrate. It is used to help the heart work more easily.

Glyceryl trinitrate works by being converted in the body to a chemical called nitric oxide. This chemical is made naturally by the body and has the effect of making the veins and arteries relax and widen (dilate). When the blood vessels dilate in this way there is more space inside them and hence less resistance. This makes it easier for the heart to pump blood around the body.

Widening the veins also decreases the volume of blood that returns to the heart with each heartbeat. This makes it easier for the heart to pump that blood out again.

As a result of both these actions, the heart does not need as much energy to pump the blood around the body and therefore needs less oxygen.

Glyceryl trinitrate also widens the arteries within the heart itself, which increases the blood and oxygen supply to the heart muscle.

The pain of angina is caused by too little oxygen reaching the heart when its workload increases, such as during exercise. Glyceryl trinitrate improves the oxygen supply to the heart, as well as decreasing the amount of oxygen that the heart needs by making it easier for the heart to pump blood around the body. It can therefore be used to treat angina.

Percutol ointment is used on a regular basis to help prevent angina attacks. The ointment is applied onto the skin without rubbing in and the medicine is absorbed continuously through the skin and into the bloodstream.

Glyceryl trinitrate is also available as short-acting sublingual tablets and sprays, which are administered under the tongue if needed to give rapid relief from angina attacks. See the factsheets linked at the end of this article for more information.

What is it used for?

  • Preventing angina attacks.

How do I use the ointment?

  • Percutol ointment should be measured onto the paper 'Applirule' provided with the medicine and this should then be pressed onto the skin on the chest, upper arm or thigh until the ointment is spread in a thin layer under the paper. The ointment should not be rubbed in, and the 'Applirule' should be secured to the skin with surgical tape.
  • With long-term continuous use the body can start to become tolerant to this medicine. To avoid this problem it is important that you have a period of between 8 and 12 hours every day when you are not using the ointment. This is usually acheived by not applying any at night, but ask your doctor or pharmacist for advice.
  • If you think that this ointment has become less effective at preventing angina attacks you should consult your doctor or pharmacist.
  • You should not suddenly stop using the ointment, as this could cause your angina to get worse. If treatment with the patches is stopped, this should be done gradually, following the instructions given by your doctor.

Warning!

  • This medicine should not be used to treat an angina attack, as it does not work quickly enough. It should be used regularly, as prescribed, to prevent angina attacks, and you should keep your glyceryl trinitrate (GTN) sublingual tablets or spray with you at all times to use if you do have an angina attack.
  • This medicine may cause dizziness and so may affect your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
  • Drinking alcohol may enhance some of the side effects of this medicine, such as feeling faint or dizzy.

Use with caution in

  • Severely decreased kidney function.
  • Severely decreased liver function.
  • People who have recently had a heart attack.
  • Underactive thyroid gland (hypothyroidism).
  • People with low levels of oxygen in their blood, eg due to lung disease.
  • Dangerously low body temperature (hypothermia).
  • Malnutrition.

Not to be used in

  • Allergy to nitrates.
  • Low blood pressure (hypotension).
  • Low volume of circulating blood (hypovolaemia).
  • Inflammation of the sac surrounding the heart that stops the heart from beating properly (constrictive pericarditis).
  • Fluid in the sac surrounding the heart that prevents the heart beating properly (cardiac tamponade).
  • Narrowing of the main artery coming from the heart (aortic stenosis).
  • Narrowing of one of the valves in the heart (mitral valve stenosis).
  • Heart disease in which the muscle of the heart grows abnormally (hypertrophic obstructive cardiomyopathy).
  • Head injury.
  • Bleeding in the brain (cerebral haemorrhage).
  • Severe anaemia.
  • Closed angle glaucoma.
  • This medicine is not recommended for use in children.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • The safety of this medicine for use during pregnancy has not been established. It should only be used during pregnancy if the benefits to the mother outweigh any risks to the developing baby. Seek medical advice from your doctor.
  • It is not known if this medicine passes into breast milk. It should only be used by breastfeeding mothers if the benefits to the mother outweigh any risks to the nursing infant. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

  • Headache.
  • Dizziness.
  • Weakness.
  • Nausea.
  • Flushing.
  • Reddening, itching or burning sensation at the application site.
  • A drop in blood pressure that occurs when moving from a lying down or sitting position to sitting or standing, which results in dizziness and lightheadedness (postural hypotension).
  • Increased heart rate (tachycardia).
  • Decreased heart rate (bradycardia).
  • Allergic skin reactions.
  • Fainting.

The side effects listed above may not include all of the side effects reported by the drug's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while using this one, to ensure that the combination is safe.

The medicines for erectile dysfunction (impotence) listed below must not be used by people using glyceryl trinitrate, because the combination can produce a severe drop in blood pressure resulting in dizziness, fainting, or even a heart attack:

  • sildenafil (Viagra)
  • tadalafil (Cialis)
  • vardenafil (Levitra).

If this medicine is used in combination with other medicines that reduce blood pressure, either as a treatment for high blood pressure (antihypertensives), or as a side effect, there may be an enhanced blood pressure lowering effect. This might make some people feel dizzy. If you do feel dizzy, you should lie down until the symptoms pass. Other medicines that can reduce blood pressure include the following:

  • ACE inhibitors, eg enalapril, captopril
  • alpha blockers, eg alfuzosin, doxazosin
  • alprostadil
  • anaesthetics
  • angiotensin II receptor antagonists, eg losartan
  • certain antipsychotic medicines, eg chlorpromazine
  • baclofen
  • benzodiazepines, eg temazepam
  • beta-blockers, eg propranolol
  • calcium channel blockers, eg diltiazem, verapamil, nifedipine
  • clonidine
  • diuretics, eg furosemide
  • hydralazine
  • levodopa
  • MAOI antidepressants, eg phenelzine
  • methyldopa
  • minoxidil
  • moxisylyte
  • moxonidine
  • other nitrates, eg isosorbide mononitrate, amyl nitrate (poppers)
  • tricyclic antidepressants, eg amitriptyline.

Other medicines containing the same active ingredient

Coro-Nitro pump spray Deponit patches Glytrin spray
GTN sublingual tablets Minitran patches Nitrocine injection
Nitro-Dur patchesNitrolingual pump sprayNitromin spray
Suscard tabletsTransiderm-nitro patches

Glyceryl trinitrate sublingual tablets, sprays and injection are also available without a brand name, ie as the generic medicine.