Angina is chest pain or discomfort when your heart muscle does not get enough oxygen-rich blood, usually due to the narrowing or blocking of the heart blood vessels. Angina itself is not a disease but a clinical manifestation of an underlying heart condition.
There are many types of angina, with stable angina being the most common one. It usually happens when you exert yourself and goes away with rest. For example, pain that comes on when you're climbing a staircase or exercise. However, angina can be more serious, or sometimes even developing into a heart attack. That is why it is important to see a doctor if you have chest pain, especially the one that radiates to arms, neck, jaw and the back.
After a thorough clinical check-up, if the doctor diagnoses you with underlying heart disease, you will be prescribed with many types of medications. Some of them are used to prevent future chest pain or heart attack; one of them is used to relieve chest pain temporarily if it happens, and it is called a sublingual glyceryl trinitrate (GTN).
What is a sublingual GTN?
GTN is a medication that is put under your tongue (i.e. it is used sublingually) when chest pain happened. It is a type of nitrate that widens the blood vessel to allow more oxygen-rich blood flows to your heart. Widening the blood vessels also reduce the resistance within, so it would be easier for the heart to pump blood. The volume of blood returns to the heart per heartbeat is also reduced, which further reduces the workload of the heart.
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How to take a GTN tablet?
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When having a chest pain/tightness, stop whatever you are doing, sit down and relax.
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Put a GTN tablet under your tongue and wait for 5 minutes.
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If your chest pain persists after 5 minutes, put another tablet under the tongue and wait for another 5 minutes. You may spit out the previous tablet if has not completely dissolved.
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If chest pain still ensues after 5 minutes, put the third tablet under your tongue. If chest pain persists, contact your doctor/call 911/get someone drives you to the hospital.
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Why do you need to put it under your tongue?
You might not know this, but actually there are a lot of blood vessels in the area beneath our tongue. Dissolving the GTN tablet sublingually allows good absorption, hence giving a rapid relief from chest pain or heart attack. Do not swallow, suck or chew the GTN tablet as this will inactivate the active ingredient and render the medication useless.
Watch out for these things!
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You may experience dizziness especially after taking this medication. To reduce dizziness, stand up slowly while holding onto a support or lying down until the dizziness subsides. Avoid operating machinery or driving when taking sublingual GTN. If you happened to have a chest pain episode when you’re driving, stop your car at the roadside if possible.
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You should not take any medications used for erectile dysfunction (male impotence) such as sildenafil or tadalafil within 12 hours of using a GTN tablet, and vice versa. This is because using both medications within a short period of time can cause abnormally low blood pressure that may be life-threatening. If you develop a chest pain within 12 hours of taking sildenafil or tadalafil, go to the hospital and tell them you are taking medications for erectile dysfunction
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It is important that your GTN tablets are kept in the original container they are dispensed in. They should not be moved to a different container because the active ingredient can evaporate from the tablets. Always close the lid tightly after you have taken a tablet. Do not put any packing material into the bottle with the tablets. Do not expose the tablets to sunlight.
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Discard your unfinished GTN tablets after 8 weeks of opening the bottle, and get a new supply from your doctor or pharmacist. This is because the medication loses its effectiveness after 8 months. This is important as you don’t want to be taking an ineffective medication or run out of fresh GTN tablets next time when you develop chest pain. Label the bottle with the expiry date when you open a new one may help.
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Always carry the GTN tablets with you in the original bottle at all times. Do not leave it in a car as high temperature may damage the medication and also in case you need to take them.
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Do not take this medication with alcohol as it can exacerbate headache, which is also one of the side effects of GTN.
There are many types of GTN, actually
Interestingly, GTN also available in spray and transdermal patch form.
If you personally find sublingual GTN tablets inconvenient to use, talk to your doctor or pharmacist to switch to other types of GTN.
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References:
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https://www.heart.org/en/health-topics/heart-attack/angina-chest-pain
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https://www.mayoclinic.org/diseases-conditions/angina/symptoms-causes/syc-20369373
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https://www.netdoctor.co.uk/medicines/heart-blood/a6820/gtn-sublingual-tablets-glyceryl-trinitrate/
