Nitrates

What are nitrates used for?
Nitrates are medicines that are used to prevent and relieve chest pain (angina) due to coronary artery disease. They belong to a class of medications called vasodilators that cause blood vessels to widen. The most common types of nitrates are nitroglycerin (glyceryl trinitrate or GTN), isosorbide dinitrate, and isosorbide mononitrate. Nitrates can be used to treat angina in three ways:

• Short-term nitrates are taken to relieve angina on an as-needed basis
• Short-term nitrates are also taken right before activities known to cause an attack to prevent angina
• Long-term nitrates are taken daily to decrease the number of angina attacks

How do nitrates work?
Heart-related chest pain occurs when the heart muscle doesn’t get as much oxygen as it needs. This is usually due to narrowing of the arteries that supply blood to the heart, which is caused by atherosclerosis – the buildup of fatty plaque on the lining of the arteries. Nitrates work by relaxing and widening the blood vessels in the body, allowing more blood and oxygen to flow to the heart.  Since the arteries are wider, it is easier for the heart to pump blood, so it does not require as much blood and oxygen.  

What is nitrate tolerance?
If you have nitrate in your bloodstream all the time, your body grows accustomed to it and the medicine will lose its ability to dilate your blood vessels and therefore its ability to prevent or relieve angina. This loss of effectiveness is called nitrate tolerance. Nitrate tolerance is not a problem for patients taking short-acting nitrates, which are only in your bloodstream for a short time. However, patients taking long-acting nitrates need to have periods during each day where there are no nitrates in the body, and this is why your medicine may be prescribed to be taken at irregular intervals throughout the day.

How are nitrates taken?
Nitrate medications come in many forms. Short-term nitrates that are used on an as-needed basis for chest pain mainly come in sublingual (under the tongue) tablets, chewable tablets, and sprays. Long-term nitrates that are taken every day to prevent chest pain come as a pill, skin patch, or ointment. Different kinds may be combined to give you the best possible relief. If you are hospitalized for chest pain or a heart procedure, you may also receive liquid nitrates through an IV.
Nitroglycerin tablets, a form of short-term nitrates, are absorbed quickly into the bloodstream when they dissolve under the tongue, and should ease chest pain within 1 to 5 minutes.  If you are taking short-term nitrates to prevent an anticipated attack, placing a tablet under the tongue 10 minutes before the activity will prevent angina for about an hour.  If you are taking long-term nitrates, you may need to take them at uneven intervals throughout the day to prevent nitrate tolerance.

How should I store my nitrate medication?
Nitrates, particularly sublingual nitroglycerin tablets, may not work as well as they should if they are exposed to heat, moisture, or air for long periods of time. You can’t tell if a tablet is working based on a tingling or burning sensation under your tongue or flushing or warmth in your face and neck — not everyone feels these effects and some newer types of tablets don’t cause them at all.  The only way to be sure your pills are working is to keep them dry in a closed bottle and be sure to throw out medication that has expired.
Nitroglycerin tablets are the least stable form of nitrates and typically need to be replaced every 3 to 6 months. Other types of nitrates such as spray nitroglycerin are not as easily ruined and can last longer. Be sure to check the expiration date on the bottle and refill your prescription before the medication expires.

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