Glyceryl Trinitrate

Glyceryl Trinitrate (also known as nitroglycerin) belongs to a class of medications called nitrate vasodilators. It helps relax the muscles on blood vessels and widen the veins and arteries. As a result, it reduces the workload of heart muscles and blood pressure. 

Glyceryl Trinitrate is commonly used to prevent and treat angina, or control of blood pressure during and after heart surgeries.

In Hong Kong, there are different forms of Glyceryl Trinitrate, including sublingual tablets and sprays, patches applied to the skin, and injections. Glyceryl Trinitrate can be used to treat an angina attack, or it can be taken 5-10 minutes before activities that can cause angina. The correct use and storage of Glyceryl Trinitrate is essential for the effective prevention and treatment of angina.

Glyceryl Trinitrate sublingual tablets and spray are designed to provide rapid relief of angina symptoms. Follow these steps to use your medicine correctly:

• When you feel an angina attack sit down. You may feel dizzy, lightheaded or faint after using the medicine.
• If you are using sublingual tablets: Place a tablet under your tongue and let it dissolve. Do not crush, chew or swallow the tablet.
• If you are using the sublingual spray: remove the cap on the bottle. Hold the bottle upright. There is no need to shake the bottle. Find the spray nozzle direction and point it towards you tongue. Press the nozzle firmly to release the spray on or under your tongue (1-2 sprays). Close your mouth, do not inhale the spray.
• If chest pain still persists after 5 minutes, use another tablet and use another spray. You may repeat in another five minutes with another tablet/spray (maximum of three tablets or sprays within 15 minutes).
• If 3 tablets/sprays are used but symptoms still persist, call an ambulance immediately or go to a hospital (do not drive yourself).
• Always keep your tablets in the original glass bottle and away from moisture, heat and direct light. Store the spray at room temperature, away from heat and out of direct light.
• Check the expiry date of your tablets/ spray frequently and promptly replace any expired Glyceryl Trinitrate.

If you are using a Glyceryl Trinitrate skin patch (Nitroderm TTS), the correct steps to use it are listed below:

• Apply a patch to a dry and clean skin every morning.
• Remove your patch before bedtime. Glyceryl Trinitrate works best when it has a daily “medicine-free” period.
• Rotate the location of the patch so as to avoid applying the patch to the same site every time.
• Fold the patch in half with the sticky side inwards. Throw the patch away in your household waste and keep out of the reach of children and pets, as it still has some active medication.

The suggested adult doses for the prevention of angina are as follows:

Sublingual tablet: 1 tablet to be used prior to activity that might cause an angina attack.

Sublingual spray: 400-800 mcg to be used prior to activity that might cause an angina attack.

Patch: Apply 1 patch in the morning and remove before bedtime.

The most common side effects of Glyceryl Trinitrate tablets and sprays are headache, flushing, rash, low blood pressure.

If you are using a Glyceryl Trinitrate patch, common side effects include headache, low blood pressure, lightheadedness, rash and itchiness.

• People who are allergic to nitroglycerin, other nitrates or nitrites, or any component of the product.
• People who are on phosphodiesterase-5 inhibitors, such as Sildenafil (Viagra), Tadalafil, or soluble guanylate cyclase stimulators such as Riociguat.

In Hong Kong, Glyceryl Trinitrate tablets, sprays and patches are over-the-counter medicines which can be purchased without a prescription from any pharmacy in Hong Kong by speaking with a pharmacist. It can also be obtained from doctors. For injectable Glyceryl Trinitrate, it is a prescription only medicine and requires a prescription from a doctor to be purchased in a pharmacy. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk