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Glyceryl Trinitrate

Drug Class: Commonly Known As: Category:
Nitrates

Glyceryl Trinitrate - Dosage and How to Use

How should Glyceryl Trinitrate be used?

  • ​Glyceryl trinitrate is available in different forms, namely sublingual (under the tongue) tablets, mouth sprays and skin patches.
  • GTN sublingual tablets or mouth spray can be used to relieve angina attacks or to prevent an expected angina attack, e.g. moments before exercising. Symptoms of an angina attack may include one or more of the following:
    • Chest pain/ chest tightness
    • Shortness of breath
    • May also be accompanied with heavy sweating, or pain that spreads to your jaw, arm or back.
  • The tablet or spray should be used at the first sign of an attack of angina. Do not wait until severe pain occurs. This medication usually provides relief within five minutes.
  • If you are using GTN to prevent an expected angina attack, you may dissolve a tablet under your tongue if using tablets or administer a spray under the tongue if using spray, five to ten minutes before you participate in an activity that could cause angina, such as exercise.
  • Directions on how to take GTN sublingual tablets:
    • Place a tablet under your tongue when you experience chest pain. Do not swallow the tablet.
    • If the pain is not relieved after five minutes, use a second tablet.
    • If you still have pain after two to three tablets, call for an ambulance (995) immediately.
      While waiting for the ambulance to arrive, continue placing a tablet under your tongue every five minutes if your pain continues.
  • Directions on how to use GTN mouth spray:
    • Before using GTN mouth spray for the first time, check that the spray is working by pressing the spray button a few times until it produces a fine liquid mist.
    • If you do not need to use GTN mouth spray very often, remember to check the spray regularly to see that it still works properly.
    • Remove the plastic cover, and do NOT shake the plastic bottle.
    • Hold the bottle upright and close to your mouth, and point the nozzle at the area under your tongue. Press the button to deliver one spray under your tongue.
    • Release the button and close your mouth. Avoid swallowing immediately after using the spray, and do NOT inhale the spray.
    • Spray once under the tongue when you have chest pain or breathing difficulties.
    • If the pain is not relieved after five minutes, use a second spray.
    • If you still have pain after two to three sprays, call for an ambulance (995) immediately.
    • Do not use GTN spray if you are near a naked flame, e.g. a cigarette.
  • GTN patches are applied to the skin to reduce the number of angina attacks.
  • Directions on how to use GTN patch:
    • Apply the patch to clean, dry skin with little or no hair, free from scars, cuts or irritation.
    • Remove the previous patch before applying a new one, and apply a new patch if the patch falls off or comes loose.
    • Apply each patch to a different area of the skin to prevent skin irritation.
    • Do not trim or cut the adhesive patch to adjust the dosage of GTN. Speak to your doctor if you see the need to adjust your dosage, or if you think your medication is not working.
    • The dose of GTN is different for different patients; follow your doctor’s instructions on when to apply and remove the skin patch. The patch is usually left on for 12 hours a day.
  • If you have been using this medication regularly for several weeks or more, do not stop using suddenly. Stopping your medication suddenly may cause angina attacks. Ask your doctor for recommendations on how to reduce the dose slowly before stopping completely.

What should I do if I miss a dose?

​For patients using GTN patches: If you miss a dose, use the missed dose as soon as you remember. If it is almost time for your next dose, use only the usual dose. Do not double your dose or use extra medication to make up for the missed dose.

What should I do if I overdose?

Glyceryl Trinitrate - Additional Information

  • Updated on Wednesday, July 31, 2019
  • Article contributed by PSS National Medication Information Workgroup PSS National Medication Information Workgroup

    The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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