Some commonly used brand names are:

In the U.S.—

In Canada—

Another commonly used name is: Glyceryl trinitrate

• Antianginal
• Vasodilator, congestive heart failure

Nitrates ( NYE-trates) are used to treat the symptoms of angina (chest pain). Depending on the type of dosage form and how it is taken, nitrates are used to treat angina in three ways:

• to relieve an attack that is occurring by using the medicine when the attack begins;
• to prevent attacks from occurring by using the medicine just before an attack is expected to occur; or
• to reduce the number of attacks that occur by using the medicine regularly on a long-term basis.

Nitrates are available in different forms. Sublingual nitrates are generally placed under the tongue where they dissolve and are absorbed through the lining of the mouth. Some can also be used buccally, being placed under the lip or in the cheek. The chewable dosage forms, after being chewed and held in the mouth before swallowing, are absorbed in the same way. It is important to remember that each dosage form is different and that the specific directions for each type must be followed if the medicine is to work properly.

Nitrates that are used to relieve the pain of an angina attack include:

• sublingual nitroglycerin;
• buccal nitroglycerin;
• sublingual isosorbide dinitrate; and
• chewable isosorbide dinitrate.

Those that can be used to prevent expected attacks of angina include:

• sublingual nitroglycerin;
• buccal nitroglycerin;
• sublingual isosorbide dinitrate; and
• chewable isosorbide dinitrate.

Products that are used regularly on a long-term basis to reduce the number of attacks that occur include:

• buccal nitroglycerin;
• chewable isosorbide dinitrate; and
• sublingual isosorbide dinitrate.

Nitrates work by relaxing blood vessels and increasing the supply of blood and oxygen to the heart while reducing its work load.

Nitrates may also be used for other conditions as determined by your doctor.

The nitrates discussed here are available only with your doctor's prescription, in the following dosage forms:

Buccal
• Nitroglycerin
  • Extended-release tablets (U.S. and Canada)

Chewable
• Isosorbide dinitrate
  • Tablets (U.S.)

Sublingual
• Isosorbide dinitrate
  • Tablets (U.S. and Canada)
• Nitroglycerin
  • Tablets (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For nitrates, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to nitrates or nitrites. Also tell your health care professional if you are allergic to any other substances, such as certain foods, preservatives, or dyes.

Pregnancy—Nitrates have not been studied in pregnant women. However, studies in rabbits given large doses of isosorbide dinitrate have shown adverse effects on the fetus. Before taking these medicines, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is not known whether these medicines pass into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking these medicines and who wish to breast-feed should discuss this with their doctor.

Children—Studies on these medicines have been done only in adult patients, and there is no specific information comparing use of nitrates in children with use in other age groups.

Older adults—Dizziness or lightheadedness may be more likely to occur in the elderly, who may be more sensitive to the effects of nitrates.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking nitrates, it is especially important that your health care professional know if you are taking any of the following:

• Antihypertensives (high blood pressure medicine) or
• Other heart medicine or
• Sildenafil—May increase the effects of nitrates on blood pressure

• Anemia (severe)

• Glaucoma—May be worsened by nitrates

• Head injury (recent) or
• Stroke (recent)—Nitrates may increase pressure in the brain, which can make problems worse

• Heart attack (recent)—Nitrates may lower blood pressure, which can aggravate problems associated with heart attack

• Kidney disease or
• Liver disease—Effects may be increased because of slower removal of nitroglycerin from the body

• Overactive thyroid

Take this medicine exactly as directed by your doctor. It will work only if taken correctly.

Sublingual tablets should not be chewed, crushed, or swallowed. They work much faster when absorbed through the lining of the mouth. Place the tablet under the tongue, between the lip and gum, or between the cheek and gum and let it dissolve there. Do not eat, drink, smoke, or use chewing tobacco while a tablet is dissolving.

Buccal extended-release tablets should not be chewed, crushed, or swallowed. They are designed to release a dose of nitroglycerin over a period of hours, not all at once.

• Allow the tablet to dissolve slowly in place between the upper lip and gum (above the front teeth), or between the cheek and upper gum. If food or drink is to be taken during the 3 to 5 hours when the tablet is dissolving, place the tablet between the upper lip and gum, above the front teeth. If you have dentures, you may place the tablet anywhere between the cheek and gum.
• Touching the tablet with your tongue or drinking hot liquids may cause the tablet to dissolve faster.
• Do not go to sleep while a tablet is dissolving because it could slip down your throat and cause choking.
• If you accidentally swallow the tablet, replace it with another one.
• Do not use chewing tobacco while a tablet is in place.

Chewable tablets must be chewed well and held in the mouth for about 2 minutes before you swallow them. This will allow the medicine to be absorbed through the lining of the mouth.

For patients using nitroglycerin or isosorbide dinitrate to relieve the pain of an angina attack:

• When you begin to feel an attack of angina starting (chest pains or a tightness or squeezing in the chest), sit down. Then place a tablet in your mouth, either sublingually or buccally, or chew a chewable tablet. This medicine works best when you are standing or sitting. However, since you may become dizzy, lightheaded, or faint soon after using a tablet, it is safer to sit rather than stand while the medicine is working. If you become dizzy or faint while sitting, take several deep breaths and bend forward with your head between your knees.
• Remain calm and you should feel better in a few minutes.
• This medicine usually gives relief in 1 to 5 minutes. However, if the pain is not relieved, and you are using:
  • Sublingual tablets, either sublingually or buccally: Use a second tablet. If the pain continues for another 5 minutes, a third tablet may be used. If you still have the chest pains after a total of 3 tablets in a 15-minute period, contact your doctor or go to a hospital emergency room immediately.
  • Buccal extended-release tablets: Use a sublingual (under the tongue) nitroglycerin tablet and check with your doctor. Do not use another buccal tablet since the effects of a buccal tablet last for several hours.

For patients using nitroglycerin or isosorbide dinitrate to prevent an expected angina attack:

• You may prevent anginal chest pains for up to 1 hour (6 hours for the extended-release nitroglycerin tablet) by using a buccal or sublingual tablet or chewing a chewable tablet 5 to 10 minutes before expected emotional stress or physical exertion that in the past seemed to bring on an attack.

For patients using isosorbide dinitrate or extended-release buccal nitroglycerin regularly on a long-term basis to reduce the number of angina attacks that occur:

• Chewable or sublingual isosorbide dinitrate and buccal extended-release nitroglycerin tablets can be used either to prevent angina attacks or to help relieve an attack that has already started.

Dosing—

The dose of nitrates will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of nitrates. If your dose is different, do not change it unless your doctor tells you to do so.

For isosorbide dinitrate
• For angina (chest pain):
  • For chewable dosage form (tablets):
    • Adults—5 mg every two to three hours, chewed well and held in mouth for one or two minutes.
    • Children—Dose must be determined by your doctor.
  • For sublingual dosage form (tablets):
    • Adults—2.5 to 5 mg every two to three hours.
    • Children—Dose must be determined by your doctor.

For nitroglycerin
• For angina (chest pain):
  • For buccal dosage form (extended-release tablets):
    • Adults—1 mg every five hours while awake. Your doctor may increase your dose.
    • Children—Dose must be determined by your doctor.
  • For sublingual dosage form (tablets):
    • Adults—300 to 600 micrograms (mcg) (0.3 to 0.6 mg) every five minutes. If you still have chest pain after a total of three tablets in fifteen minutes, call your doctor or go to the emergency room right away.
    • Children—Dose must be determined by your doctor.

Missed dose—

For patients using isosorbide dinitrate or extended-release buccal nitroglycerin regularly on a long-term basis to reduce the number of angina attacks that occur:

• If you miss a dose of this medicine, use it as soon as possible. However, if the next scheduled dose is within 2 hours, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Stability and proper storage

For sublingual nitroglycerin

• Sublingual nitroglycerin tablets may lose some of their strength if they are exposed to air, heat, or moisture for long periods of time. However, if you screw the cap on tightly after each use and you properly store the bottle, the tablets should retain their strength until the expiration date on the bottle.
• Some people think they should test the strength of their sublingual nitroglycerin tablets by looking for a tingling or burning sensation, a feeling of warmth or flushing, or a headache after a tablet has been dissolved under the tongue. This kind of testing is not completely reliable since some patients may be unable to detect these effects. In addition, newer, stabilized sublingual nitroglycerin tablets are less likely to produce these detectable effects.
• To help keep the nitroglycerin tablets at full strength:
  • keep the medicine in the original glass, screw-cap bottle. For patients who wish to carry a small number of tablets with them for emergency use, a specially designed container is available. However, only containers specifically labeled as suitable for use with nitroglycerin sublingual tablets should be used.
  • remove the cotton plug that comes in the bottle and do not put it back.
  • put the cap on the bottle quickly and tightly after each use.
  • to select a tablet for use, pour several into the bottle cap, take one, and pour the others back into the bottle. Try not to hold them in the palm of your hand because they may pick up moisture and crumble.
  • do not keep other medicines in the same bottle with the nitroglycerin since they will weaken the nitroglycerin effect.
  • keep the medicine handy at all times but try not to carry the bottle close to the body. Medicine may lose strength because of body warmth. Instead, carry the tightly closed bottle in your purse or the pocket of a jacket or other loose-fitting clothing whenever possible.
  • store the bottle of nitroglycerin tablets in a cool, dry place. Storage at average room temperature away from direct heat or direct sunlight is best. Do not store in the refrigerator or in a bathroom medicine cabinet because the moisture usually present in these areas may cause the tablets to crumble if the container is not tightly closed. Do not keep the tablets in your automobile glove compartment.
• Keep out of the reach of children.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

For isosorbide dinitrate and buccal extended-release nitroglycerin

• These forms of nitrates are more stable than sublingual nitroglycerin.
• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Do not take sildenafil (e.g., Viagra) if you are taking this medicine. When sildenafil is taken with nitrates, the combination can lower blood pressure and cause dizziness, lightheadedness, or fainting. In some case, sildenafil taken with nitrates has caused death.

If you have been taking this medicine regularly for several weeks, do not suddenly stop using it. Stopping suddenly may bring on attacks of angina. Check with your doctor for the best way to reduce gradually the amount you are taking before stopping completely.

Dizziness, lightheadedness, or faintness may occur , especially when you get up quickly from a lying or sitting position. Getting up slowly may help. If you feel dizzy, sit or lie down.

The dizziness, lightheadedness, or fainting is also more likely to occur if you drink alcohol, stand for long periods of time, exercise, or if the weather is hot. While you are taking this medicine, be careful to limit the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for long periods of time.

After taking a dose of this medicine you may get a headache that lasts for a short time. This is a common side effect, which should become less noticeable after you have taken the medicine for a while. If this effect continues or if the headaches are severe, check with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Rare
  • Blurred vision;  dryness of mouth;  headache (severe or prolonged);  skin rash 
  
  

• Signs and symptoms of overdose (in the order in which they may occur)
  • Bluish-colored lips, fingernails, or palms of hands;  dizziness (extreme) or fainting;  feeling of extreme pressure in head;  shortness of breath ;  unusual tiredness or weakness;  weak and fast heartbeat;  fever;  convulsions (seizures) 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Dizziness or lightheadedness, especially when getting up from a lying or sitting position;  fast pulse;  flushing of face and neck;  headache ;  nausea or vomiting;  restlessness  
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.