nitroglycerin (glyceryl trinitrate) Pharmacologic classification: nitrate
Nitro-Bid, Nitroglyn, Nitrong, Nitrong SR ◆, Nitro-Time
Nitro-Bid IV, Tridil
Nitro-Bid, Nitrol, Nitrol Appli-Kit
Deponit, Minitran, Nitrodisc, Nitro-Dur, Transderm-Nitro
Therapeutic classification: antianginal, vasodilator
Pregnancy risk category C
Available by prescription only
Aerosol (lingual): 0.4 mg/metered spray
Capsules (extended-release): 2.5 mg, 6.5 mg, 9 mg, 13 mg
I.V.: 0.5 mg/ml, 5 mg/ml
I.V. premixed solutions in dextrose: 100 mcg/ml, 200 mcg/ml, 400 mcg/ml
Tablets (buccal, controlled-release): 2 mg, 3 mg
Tablets (S.L.): 0.3 mg, 0.4 mg, 0.6 mg
Topical: 2% ointment
Transdermal: 0.1-mg, 0.2-mg, 0.3-mg, 0.4-mg, 0.6-mg/hour systems, 0.8-mg/hour systems
Indications and dosages
Prophylaxis against chronic anginal attacks. Adults: 2.5 to 9 mg P.O. q 8 to 12 hours. Or, 1/2 inch of 2% ointment, increasing in 1/2-inch increments until desired effect is achieved.
Range of dosage with ointment is 0.5 to 4 inches q 4 to 6 hours. Usual dose is 1 to 2 inches. Or, transdermal disc or pad
may be applied to hairless site once daily. However, to prevent tolerance, topical forms shouldn’t be worn overnight.
Relief of acute angina pectoris, prophylaxis to prevent or minimize anginal attacks when taken immediately before stressful
events. Adults: One S.L. tablet dissolved under the tongue or in the buccal pouch immediately after onset of anginal attack. May repeat q
5 minutes for 15 to 30 minutes for a maximum of three doses. Or, using Nitrolingual spray, spray one or two doses into mouth,
preferably onto or under the tongue. May repeat q 3 to 5 minutes to a maximum of three doses within a 15-minute period. Or,
transmucosally, 1 to 3 mg q 3 to 5 hours during waking hours.
Hypertension, heart failure, angina. Nitroglycerin is indicated to control hypertension related to surgery, to treat heart failure caused by MI, to relieve angina
pectoris in acute situations, and to produce controlled hypotension during surgery (by I.V. infusion).
Adults: Initial infusion rate is 5 mcg/ minute. May be increased by 5 mcg/minute q 3 to 5 minutes until a response is noted. If a
20-mcg/ minute rate does not produce desired response, dosage may be increased by as much as 10 to 20 mcg/minute q 3 to 5
Acute MI. Adults: Initially, 12.5 to 25 mcg I.V. followed by an infusion at 10 to 20 mcg/minute; increase 5 to 10 mcg/minute q 5 to 10 minutes
as needed. Maximum dose is 200 mcg/minute. Decrease or discontinue if mean arterial pressure is under 80 mm Hg or systolic
blood pressure under 90 mm Hg.
Hypertensive crisis ◇. Adults: Infuse at 5 to 100 mcg/minute I.V.
Antianginal action: Nitroglycerin relaxes vascular smooth muscle of both the venous and arterial beds, resulting in a net decrease in myocardial
oxygen consumption. It also dilates coronary vessels, leading to redistribution of blood flow to ischemic tissue. Systemic
and coronary vascular effects of drug, which may vary slightly with the various nitroglycerin forms, probably account for
its value in treating angina.
Vasodilating action: Nitroglycerin dilates peripheral vessels, making it useful (in I.V. form) in producing controlled hypotension during surgical
procedures and in controlling blood pressure in perioperative hypertension. Because peripheral vasodilation decreases venous
return to the heart (preload), nitroglycerin also helps to treat pulmonary edema and heart failure. Arterial vasodilation
decreases arterial impedance (afterload), thereby decreasing left ventricular work and aiding the failing heart. These combined
effects may prove valuable in treating some patients with acute MI.
Absorption: Well absorbed from the GI tract. However, because it undergoes first-pass metabolism in the liver, it’s incompletely absorbed
into the systemic circulation. Onset of action for oral preparations is slow (except for S.L. tablets). After S.L. administration,
absorption from the oral mucosa is relatively complete. Nitroglycerin also is well absorbed after topical administration as
an ointment or transdermal system.
Distribution: Distributed widely throughout the body. About 60% of circulating drug is bound to plasma proteins.
Metabolism: Metabolized in the liver and serum to 1,3 glyceryl dinitrate; 1,2 glyceryl dinitrate; and glyceryl mononitrate. Dinitrate
metabolites have a slight vasodilatory effect.
Excretion: Metabolites are excreted in urine; elimination half-life is about 1 to 4 minutes.
Contraindications and precautions
Contraindicated in patients hypersensitive to nitrates and in those with early MI (S.L. form), severe anemia, increased intracranial
pressure, angle-closure glaucoma, orthostatic hypotension, and allergy to adhesives (transdermal form). I.V. form is contraindicated
in patients hypersensitive to I.V. form, cardiac tamponade, restrictive cardiomyopathy, or constrictive pericarditis. Extended-release
preparations shouldn’t be used in patients with organic or functional GI hypermotility or malabsorption syndrome.
Use cautiously in patients with hypotension or volume depletion.
Drug-drug. Antihypertensives, phenothiazines: May cause additive hypotensive effects. Use together cautiously.
Ergot alkaloids: May precipitate angina. Avoid use together.
Sildenafil: Potentiates hypotensive effects of nitrates. Don’t use together.
Drug-lifestyle. Alcohol use: May cause additive hypotensive effects. Discourage alcohol use.
CNS: headache, sometimes with throbbing; dizziness; weakness.
CV: orthostatic hypotension, tachycardia, flushing, palpitations, fainting.
GI: nausea, vomiting, sublingual burning.
GU: dysuria, urinary frequency, impotence.
Skin: cutaneous vasodilation, contact dermatitis (patch), rash.
Other: hypersensitivity reactions.
Effects on lab test results
Overdose and treatment
Effects of overdose result primarily from vasodilation and methemoglobinemia and include hypotension, persistent throbbing
headache, palpitations, visual disturbances, flushing of the skin, sweating (with skin later becoming cold and cyanotic),
nausea and vomiting, colic, bloody diarrhea, orthostasis, initial hyperpnea, dyspnea, slow respiratory rate, bradycardia,
heart block, increased intracranial pressure with confusion, fever, paralysis, tissue hypoxia (from methemoglobinemia) leading
to cyanosis, and metabolic acidosis, coma, clonic seizures, and circulatory collapse. Death may result from circulatory collapse
Treatment includes gastric lavage followed by administration of activated charcoal to remove remaining gastric contents. Monitor
blood gas measurements and methemoglobin levels, as indicated. Supportive care includes respiratory support and oxygen administration,
passive movement of the limbs to aid venous return, and recumbent positioning.
ALERT Don’t confuse Nitro-Bid with Nicobid or nitroglycerin with nitroprusside.
Ask all patients about the use of sildenafil (Viagra) before using nitrates.
Use only S.L. and translingual forms to relieve acute anginal attack.
S.L. dose may be taken before anticipated stress or at bedtime if angina is nocturnal.
To apply ointment, spread in uniform thin layer to hairless part of skin except distal parts of arms or legs, because absorption
won’t be maximal at these sites. Don’t rub in. Cover with plastic film to aid absorption and to protect clothing. If using
Tape-Surrounded Appli-Ruler (TSAR) system, keep TSAR on skin to protect patient’s clothing and ensure that ointment remains
in place. If serious adverse effects develop in patients using ointment or transdermal system, remove product at once or wipe
ointment from skin. Be sure to avoid contact with ointment.
Remove transdermal patch before defibrillation. Aluminum backing may cause patch to explode when exposed to electric current.
When terminating transdermal nitroglycerin treatment for angina, gradually reduce dosage and frequency of application over
4 to 6 weeks.
Administration as I.V. infusion requires special nonabsorbent tubing supplied by manufacturer; regular plastic tubing may
absorb up to 80% of drug. Prepare infusion in a glass bottle or container.
If drug causes headache, which is especially likely with early doses, aspirin or acetaminophen may be indicated. Dosage may
need to be reduced temporarily.
Drug may cause orthostatic hypotension. To minimize it, patient should change to upright position slowly, move up and down
stairs carefully, and lie down at the first sign of dizziness.
To prevent withdrawal symptoms, reduce dosage gradually after long-term use of oral or topical preparations.
Nitrate tolerance may develop.
Nitroglycerin may interfere with serum cholesterol determination tests using the Zlatkis-Zak color reaction, resulting in
falsely decreased values.
Methemoglobinemia may occur in infants receiving large doses of nitroglycerin.
Instruct patient to take drug regularly, if prescribed, and to keep S.L. form accessible at all times. Drug is physiologically
necessary but not addictive.
Teach patient to take oral tablet on empty stomach, either 30 minutes before or 1 to 2 hours after meals, to swallow oral
tablets whole, and to chew chewable tablets thoroughly before swallowing.
Instruct patient to take S.L. tablet at first sign of anginal attack. Tell him to wet tablet with saliva, place it under the
tongue until completely absorbed, and sit down and rest. If no relief occurs after three tablets, he should call for help
or go to a hospital emergency room. If he complains of tingling sensation with S.L. form, he may try holding tablet in buccal
Advise patient to store S.L. tablets in original container or other container specifically approved for this use away from
heat and light. Tell him to keep cap to bottle tightly closed.
Advise patient to discard S.L. tablets 6 months after opening.
Instruct patient to place transmucosal tablet under upper lip or in buccal pouch, to let it dissolve slowly over a 3- to 5-hour
period, and not to chew or swallow tablet. Advise him that dissolution rate may increase if he touches tablet with tongue
or drinks hot liquids.
If patient is receiving nitroglycerin lingual aerosol (Nitrolingual), instruct him how to use this device correctly. Remind
him not to inhale spray but to release it onto or under the tongue. Also tell him not to swallow immediately after administering
the spray but to wait about 10 seconds before swallowing.
Caution patient to use care when wearing transdermal patch near a microwave oven because leaking radiation may heat metallic
backing of patch and cause burns.
Warn patient that headache may follow initial doses but that this symptom may respond to usual headache remedies or dosage
reduction (dosage should be reduced only with medical approval). Assure patient that headache usually subsides gradually with
Instruct patient to avoid alcohol while taking drug because severe hypotension and CV collapse may occur.
Warn patient that drug may cause dizziness or flushing and that he should move to an upright position slowly.
Tell patient to report blurred vision, dry mouth, or persistent headache.
Reactions may be common, uncommon, life-threatening, or
COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use