Detailed Drug Information:

DRUG CLASS AND MECHANISM: Nitroglycerin is a vasodilator (amedication that dilates blood vessels) that frequently is used in themanagement of angina pectoris. Synthesized in 1846, nitroglycerin wasfirst used to treat anginal attacks in 1879. It was granted FDA approvalin 1938.

Blood returning from the body in the veins must be pumped by the heartthrough the lungs and into the arteries against the high pressure in thearteries. In order to accomplish this work, the heart's muscle mustproduce and use energy ("fuel"). The production of energyrequires oxygen. Angina pectoris (angina) or "heart pain" is dueto an inadequate flow of blood (and oxygen) to the muscle of the heart. Itis believed that all nitrates, including nitroglycerin, correct theimbalance between the flow of blood and oxygen to the heart and the workthat the heart must do by dilating the arteries and veins in the body.Dilation of the veins reduces the amount of blood that returns to theheart that must be pumped . Dilation of the arteries lowers the pressurein the arteries against which the heart must pump. As a consequence, theheart works less and requires less blood and oxygen.

Additionally, in patients with angina, nitroglycerin preferentiallydilates blood vessels that supply the areas of the heart where there isnot enough oxygen, thereby delivering oxygen to the heart tissue thatneeds it most.

GENERIC AVAILABLE: yes (for some dosage forms)

PREPARATIONS: extended-release capsules containing 2.5, 6.5, 9,or 13 mg; 2% ointment with tape for application; patches (or transdermaldelivery systems) which deliver 0.1, 0.2, 0.3, 0.4, 0.6, or 0.8 mg ofnitroglycerin per hour; buccal tablets containing 1, 2, or 3 mg ofnitroglycerin in an extended-release formulation; a translingual spraywhich delivers 0.4 mg of nitroglycerin per spray; sublingual tabletscontaining 0.15 or 0.3mg.

STORAGE: All formulations should be kept at room temperature,15-30°C (59-86°F). The sublingual tablets are especiallysusceptible to moisture. They should NOT be kept in bathrooms or kitchensbecause of the higher degrees of moisture there. Care should be taken toreplace the sublingual tablets every six months.

PRESCRIBED FOR: Nitroglycerin is indicated for the acutetreatment and prevention of angina.

DOSING: For the treatment of acute angina attacks or for acuteprevention (i.e. immediately before encountering situations likely tobring on an anginal attack): one tablet is allowed to dissolve under thetongue or in the buccal pouch (between the cheek and gums), or one sprayis given of the lingual spray. (Nitroglycerin for sublingual or buccal useas well as spray are rapidly absorbed from the lining of the mouth forimmediate effects.) This may be repeated every 5 minutes as needed. Ifangina is not relieved after a total of 3 doses, the patient should betaken to a hospital or a physician should be contacted. If lingual sprayis used, the canister of spray should not be shaken prior to use, and itshould be sprayed onto or under the tongue and then the mouth closed.

For prevention of angina, ointment may be applied using specialdose-measuring application papers provided with the ointment. Theappropriate amount of ointment is squeezed as a thin layer onto the paper,and the paper is used to spread the ointment onto nonhairy area of skin.The ointment should not be allowed to come into contact with the hands sothat there is no absorption from the hands. Transdermal patches also areused for prevention. Patches may be applied to any hairless site butshould not be applied to areas with cuts or calluses. Firm pressure shouldbe used over the patch to ensure contact with the skin. The patch shouldnot be cut or trimmed . Patches are waterproof and should not be affectedby showering or bathing. Capsules of long-acting nitroglycerin also areused for prevention. They usually are prescribed 2 to 3 times per day andare taken 1 to 2 hours after a meal.

DRUG INTERACTIONS: Since nitroglycerin can cause hypotension(low blood pressure), other medications which also cause hypotension mayproduce an unwanted additive effect. Such drugs might include medicinesused to treat high blood pressure, some antidepressants; someanti-psychotics, quinidine, procainamide, benzodiazepines such as diazepam (Valium) or opiates (e.g. morphine). Since alcohol also may intensify theblood pressure lowering effect of nitroglycerin, patients receivingnitroglycerin should be advised to drink alcoholic beverages with caution.

Ergot alkaloids (e.g. Cafergot) and Imitrex can oppose the vasodilatoryactions of nitroglycerin and may precipitate angina. A similar effect canoccur with ephedrine and the decongestants pseudoephedrine (Sudafed) andpropanolamine.

PREGNANCY: Since most persons who use nitroglycerin are over 50years of age, experience with the use of nitroglycerin during pregnancy islimited. Nitroglycerin can be used during pregnancy if in the judgment ofthe physician the potential benefits justify the potential (thoughunknown) risks to the fetus.

NURSING MOTHERS: It is not known if nitroglycerin is secreted in breast milk.

SIDE EFFECTS: A persistent, throbbing headache commonly occurswith nitroglycerin therapy. Aspirin, acetaminophen, or ibuprofen may beused to relieve the pain. Flushing of the head and neck can occur withnitroglycerin therapy as can an increase in heart rate or palpitations.This can be associated with a drop in blood pressure which can beaccompanied by dizziness or weakness. To reduce the risk of low bloodpressure, patients often are told to sit or lie down during andimmediately after taking nitroglycerin.