Nitroglycerin and Other Nitrates

What are nitroglycerin and nitrates?

Nitroglycerin and other nitrates are medicines used to treat some types of heart disease.

How do they work?

Nitroglycerin and nitrates relax and expand (dilate) veins and arteries. This has at least 2 good effects:

• More oxygen-carrying blood can flow through the blood vessel. This brings more oxygen to the heart muscle.
• Your blood pressure gets a little lower. Then the heart does not have to work as hard, and it does not need as much oxygen.

Expanding the blood vessels and slightly lowering blood pressure can quickly relieve chest discomfort or pain.

When are they used?

These medicines are very effective for treating angina (chest pain). Angina is discomfort in the chest that may come on during exercise and go away with rest. It is usually caused by blockage in the arteries that bring blood to the heart muscle (the coronary arteries).

Nitrates are also used to treat heart failure. Heart failure happens when the heart muscle cannot squeeze well enough to pump enough blood to meet the body's needs.

How are they used?

Nitroglycerin and nitrates are available in several forms:

• patches that release medicine through the skin
• ointment that is absorbed through your skin
• long-acting capsules or tablets that you swallow
• tablets that dissolve in your mouth
• liquid that is sprayed onto or under the tongue.

The forms of nitroglycerin and other nitrates that dissolve in your mouth or are sprayed into your mouth act very fast (usually in about 2 minutes), but their effect does not last long (about 20 to 40 minutes). They should be taken when chest pain or discomfort starts. They can also be taken before you start physical activity to prevent chest symptoms from starting. Because the effect of rapid-acting nitroglycerin and other nitrates lasts for just a short time, it is not a good medicine for long-term control of angina.

Nitrates that come in extended-release capsules, extended-release tablets, ointments, and patches work for a longer time (up to 6 hours or longer). They are used for the long-term control of angina. Do not stop taking these medicines suddenly if you are using them for long-term control of angina.

Nitroglycerin is the only nitrate available for use intravenously (by vein). Nitroglycerin by vein is especially useful for the treatment of unstable angina (chest pain) or for a heart attack.

What should I watch out for?

Nitrates often cause headaches. The headaches usually get better after you have taken these medicines for a while. Aspirin or acetaminophen tablets can give some relief for the headaches, but some people may not be able to take long-acting nitrates because of the headaches. The patch may also cause some itching or a rash on the skin. Nitroglycerin tablets may cause burning or stinging under the tongue.

Low blood pressure caused by the nitrates may cause problems. You may have fainting spells. Take the medicine while you are sitting or lying down to help prevent such problems until you know how this medicine affects you.

Other medicines can interact with nitroglycerin and nitrates. Do not take sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra) while you are taking this medicine. Using these medicines with nitrate medicine may cause severe or life-threatening low blood pressure. Always tell your healthcare provider about any other medicines you are taking because there could be unwanted side effects.

If you use any form of nitrates for a long time, your body gets used to it. The medicine may not work as well as it once did. Nitrates work best when you stop using them for at least 10 hours during a 24-hour period. Carefully follow your healthcare provider's instructions for taking the medicine. Tell your provider if you think this medicine is not working as well for you as when you first started taking it.

Doses are different for different people. Your healthcare provider will work with you to find the best dose and schedule for you.

When should I call my healthcare provider?

Call 911 if:

• You have chest pressure, squeezing, or pain that lasts more than 5 minutes or goes away and comes back.
• You have pain or discomfort in one or both arms, neck, jaw, or upper back that lasts more than 5 minutes or goes away and comes back and lightheadedness, trouble breathing, nausea or sweating.

Tell your provider right away if:

• You have a severe headache or one that does not go away.
• You have severe or ongoing lightheadedness or fainting.
• You have a very fast heartbeat.

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Written by Donald L. Warkentin, MD.
Published by RelayHealth.
© 2009 RelayHealth and/or its affiliates. All Rights Reserved.