Nitroset SR

Indications

Nitroglycerin (also called glyceryl trinitrate) is used for:

• Quick relief of an angina attack (chest pain caused by narrowed heart arteries)
• Preventing angina just before activity that usually brings it on
• Long-term prevention of angina (long-acting tablets, patches or ointment)
• In hospital, as a drip, for heart failure with fluid on the lungs, unstable angina, and control of blood pressure during surgery

How It Works

Nitroglycerin releases nitric oxide in the body, which relaxes and widens blood vessels. This lowers the work the heart has to do and improves blood flow to the heart muscle, easing chest pain.

Dosage and Administration

• Under-the-tongue spray (usually 400 micrograms per spray): at the start of chest pain, sit down and spray 1 or 2 puffs under the tongue, then close the mouth. Do not inhale the spray.
• Under-the-tongue tablets: let 1 tablet dissolve under the tongue at the start of pain; do not swallow it.
• If the pain is not better 5 minutes after the first dose, take a second dose. If the pain is still there 5 minutes after the second dose, call for emergency help or go to hospital straight away.
• Long-acting tablets, patches and ointment: use as prescribed. With patches, a patch-free gap of several hours each day (often overnight) is usually advised so the medicine keeps working.
• Injection: given in hospital by a doctor or nurse as a controlled drip into a vein.

Interactions

• Never use with Sildenafil, Tadalafil, Vardenafil or Avanafil (medicines for erectile problems or lung blood pressure) or with Riociguat. Together they can cause a dangerous fall in blood pressure.
• Other blood pressure medicines, water tablets, some antidepressants and alcohol can increase dizziness and low blood pressure.
• When given as a drip, it may reduce the effect of Heparin.

Contraindications

• Allergy to nitrates
• Very low blood pressure, shock or collapse
• Taking Sildenafil, Tadalafil, Vardenafil, Avanafil or Riociguat
• Some heart conditions such as severe narrowing of the heart valves (aortic or mitral stenosis), hypertrophic obstructive cardiomyopathy, constrictive pericarditis or fluid pressing on the heart (cardiac tamponade)
• Raised pressure inside the head, including after a head injury or brain bleed
• Severe anaemia

Side Effects

Common side effects include headache (often throbbing, usually easing with continued use), flushing, dizziness or light-headedness especially on standing, a fast heartbeat and nausea. Patches and ointment can irritate the skin.

Get urgent medical help if there is:

• Chest pain that does not ease after 2 doses taken 5 minutes apart
• Fainting, or feeling very faint even when lying down
• Swelling of the face or throat, difficulty breathing or a widespread rash
• Bluish lips or fingertips with breathlessness

Pregnancy and Lactation

There is limited information on use in pregnancy. It may be used when the doctor feels it is needed. It is not known whether it passes into breast milk; the doctor will advise.

Precautions and Warnings

• Always sit down before using the spray or tablet, as it can cause dizziness or fainting.
• Carry the medicine with you and check the expiry date.
• Do not stop long-term nitrates suddenly, as angina may get worse.
• The body can get used to nitrates (tolerance) if they are used continuously; follow the dosing gaps advised.
• Remove patches before an MRI scan or the use of a heart defibrillator.
• Use with care in older people, people with low blood pressure, a recent heart attack, an underactive thyroid or glaucoma.
• Alcohol can make dizziness worse.

Overdose

Too much can cause a severe drop in blood pressure, fainting, a pounding headache, a fast heartbeat, vomiting and, rarely, bluish skin due to a blood problem called methaemoglobinaemia. Lie the person down with legs raised and get emergency help straight away.

Therapeutic Class

Nitrate vasodilator, antianginal medicine.

Storage

Store below 30°C, away from light and out of the reach of children. Keep under-the-tongue tablets tightly closed in their original container and replace them as the pack directs after opening. The spray is flammable: do not pierce or burn the can and keep it away from flames. Keep patches in their sealed pouches until use.