Question

Mr. Jackson carries a diagnosis of coronary artery disease and sometimes experiences exertional angina. When this occurs he uses 1 tablet of NTG 0.4 mg SL which relieves the discomfort. What medication is absolutely contraindicated when using NTG and why ? What should be advised if the patient experiences non exertional chest pain and why?

Answer 1

Nitroglycerin forms free radical nitric oxide (NO), which in turn activates chemicals in the blood that cause smooth muscle to relax, resulting in vasodilation. Nitroglycerin is primarily metabolized by liver enzymes.

Sublingual forms of nitroglycerin are absorbed quickly, in one to three minutes, with peak effects in about five to 10 minutes. Sublingual doses of nitroglycerin continue to work for approximately 30 minutes, but with less effect.

Sublingual nitroglycerin is typically administered one tablet or spray every five minutes up to three doses. Some prehospital protocols recommend continuing dosage and even administering higher dose nitroglycerin two to three sublingual doses together in cases of hypertensive congestive heart failure.

Sublingual nitroglycerin is typically discontinued once the desired effect is achieved (typically reduced anginal chest pain or relieved symptoms of congestive heart failure) or if contraindications are encountered.

Transdermal forms of nitroglycerin work more slowly, but maintain therapeutic levels over a much longer period of time, typically 12 to 24 hours. Transdermal nitroglycerin is typically applied by patients to prevent the development of anginal chest pain and by EMS providers to help maintain consistent therapeutic levels of nitroglycerin in the field after administration of sublingual nitroglycerin.

CONTRAINDICATIONS OF NITROGLYCERIN

ABSOLUTE: Discontinue nitroglycerin administration or do not administer nitroglycerin to patients who:

• Have a known sensitivity to nitrate medications
• Have taken erectile dysfunction medications within the past 24 hours, such as Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil or vardenafil.
• Are hypotensive (typically <90 SBP or <65 MAP)
• Are children under 12 years old
• Are experiencing increased intracranial pressure
• Have severe anemia

RELATIVE: Nitroglycerin administration may be considered with caution to patients who:

Have a known or suspected right ventricular infarct and are thus heavily dependent on maintaining pre-load (although recent studies have found few complications with administration of nitro in RV infarcts)

Noncardiac chest pain is defined as recurrent chest pain that is indistinguishable from ischemic heart pain after a reasonable workup has excluded a cardiac cause. Noncardiac chest pain is a prevalent disorder resulting in high healthcare utilization and significant work absenteeism

When non-cardiac chest pain is caused by a muscle problem, simple treatments, such as a heating pad, stretching exercises, or over-the-counter pain relievers like ibuprofen, can relieve the pain. Non-cardiac chest pain can be due to stress, aNitroglycerin is a vasodilator that has an especially strong effect on vascular smooth muscle found in peripheral veins. Arterial vasodilation may also occur at higher doses of nitroglycerin.