Nitrates are a group of drugs used to prevent and treat angina (chest pain) caused by coronary artery disease.
- Glyceryl trinitrate
- Isosorbide dinitrate
- Isosorbide mononitrate
Nitrate drugs are often used in conjunction with various other drugs in the treatment of angina, a disabling chest pain that occurs when too little oxygen reaches the heart muscle.
Nitrates may be prescribed to prevent angina attacks or to relieve the symptoms of an attack when it happens. However, nitrates do not treat the underlying cause of angina, which is usually narrowing of the coronary arteries due to build-up of fatty deposits (see Coronary artery disease).
How do nitrate drugs work?
Nitrates cause blood vessels in the body to dilate (widen), making it easier for the heart to pump blood around the body. This reduces the oxygen requirement of the heart muscle. Nitrates also make the coronary arteries dilate, which improves the blood supply to the heart muscle.
How are nitrate drugs used?
Nitrates may be used either to provide rapid relief from an angina attack or to prevent an attack occurring. “Reliever” nitrates provide fast relief from chest pain in the event of an angina attack, but are effective for only 20-30 minutes. These drugs are available as tablets that you place under your tongue or between your upper lip and gum, and as an aerosol spray that is sprayed under the tongue (see Using sublingual sprays). Your doctor may advise you to use a fast-acting nitrate just before exerting yourself.
A long-acting nitrate takes more time to become effective than a fast-acting nitrate but it may continue to have an effect for several hours. Long-acting nitrates may be prescribed as skin patches, ointment, or tablets, usually taken once or twice a day. Skin patches, which may be applied to the chest, arm, back, abdomen, or thigh, are useful if you have angina at night. Skin patches should be applied to a different part of the skin each day. Nitrate drugs may also be administered intravenously in hospital as an emergency treatment to relieve an angina attack.
What are the side effects of nitrate drugs?
Nitrates commonly cause a throbbing headache and flushing. They can also cause a fall in blood pressure, resulting in light-headedness when you stand up.
If you are using a long-acting nitrate, you may develop tolerance, resulting in a reduction of the drug's effectiveness. Tolerance can be avoided by interrupting use of a skin patch or an ointment for 4-8 hours each day. Usually, long-acting nitrate pills allow levels of the drug in the blood to fall overnight.
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