Nitrates (Medication)

Nitrates are medications used for treating or preventing heart pain (angina, chest pain) caused by heart disease, usually of the arteries in the heart.

Nitrates are vasodilators (dilators of blood vessels that increase their diameter) that allow blood to flow more easily. Blood returning from the body in the veins must be pumped by the heart through the lungs and into the body's arteries against the high pressure in the arteries. In order to accomplish this work, the heart's muscle must produce and use energy ("fuel"), and this requires consumption of oxygen that is supplied by the blood. Angina (angina pectoris or "heart pain") is due to an inadequate flow of blood (and oxygen) to the muscle of the heart.

Nitrates, including isosorbide dinitrate, increase the flow of blood and oxygen to the heart and thereby increase the amount of work that the heart can do by dilating (expanding) the arteries and veins in the body. Dilation of the veins reduces the amount of blood that returns to the heart that must be pumped, while dilation of the arteries lowers the pressure in the arteries against which the heart must pump. As a consequence of both effects, the heart works less and requires less blood and oxygen.

Examples of generic and brand names of nitrates include:

• nitroglycerin sublingual tablet (Nitrostat)
• nitroglycerin lingual aerosol (Nitromist)
• nitrolinglycerin pumpspray (Nitrolingual Pumpsprapy)
• nitroglycerin lingual (Nitrolingual Pumpspray)
• nitroglycerin transdermal ointment (Nitro-Bid)
• nitroglycerin transdermal infusion system (Nitro-Dur)
• nitroglycerin transdermal therapeutic system (Transderm-Nitro)
• Nitroglycerin oral capsule (Nitro-Time)
• nitroglycerin intravenous
• isosorbide mononitrate and dinitrate (Isordil, Isordil Titradose, Dilatrate-SR))

Common side effects of nitrates include:

• Headache
• Dizziness
• Lightheadedness
• Nausea
• Flushing
• Burning and tingling under the tongue
• Low blood pressure

Other side effects include:

• Skin irritation
• Itching
• Topical allergic reactions may also occur with the topical patch form

• The FDA classifies nitrates as pregnancy category C, which means that safe and effective use of nitrates in pregnant women has not been established. Nitrates should be given to pregnant women only if clearly needed.
• It is not known whether nitrates enter breast milk; therefore, nitrates must be used with caution in women who are breastfeeding.

• Nitrates can slow down metabolism of cabergoline and ergonovine, resulting in an increase in systolic blood pressure and an increased likelihood of angina symptoms.
• Sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) increase the blood pressure lowering effects of nitrates and may cause excessive blood pressure reduction. Men taking nitrates should not take sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra).

Nitrates are available in various formulations. Nitroglycerin is available in:

• oral capsule
• sublingual tablet
• sublingual spray
• intravenous solution
• topical ointment
• topical patch
• isosorbide mononitrate and isosorbide dinitrate are available as immediate and extended-release tablets

Only sublingual tablets, intravenous, or immediate release tablets are used for immediate treatment of angina because the onset of action of the other formulations is not fast enough.