The American Heart Association (AHA) has conservatively estimated that more than 6 million Americans have chest pain. Chest pain, or angina, is a clinical syndrome that usually occurs in patients with the underlying disease process of ischemic heart disease. Angina is characterized by discomfort in the jaw, chest, shoulder, back or arm. Patients often describe their anginal pain as squeezing, grip - like, pressure or heaviness. Anginal pain is usually not sharp or stabbing, nor does it change with respirations or position.
Ischemic heart disease is responsible for one of every 4.8 deaths making it the single leading cause of death in the United States (AHA Guidelines Chronic Stable Angina). Ischemia can be defined as inadequate oxygenation or blood flow to the myocardium. Angina symptoms occur when cardiac workload and myocardial oxygen demand exceed the ability of the coronary arteries to supply adequate oxygenation. Myocardial oxygen demand is directly related to heart rate, preload, force of contraction and afterload. Treatment of angina includes decreasing myocardial oxygen demand. The drug of choice for acute angina attacks, used for the last 100 years, is nitroglycerin (NTG).
How It Works
NTG relaxes vascular smooth muscle throughout the body. The therapeutic action for NTG is due to potent vasodilation of veins and arteries. Venous dilation causes a decrease in preload, which is the amount of stretch at the end of diastole. Decreasing preload has the direct effect of decreasing the force of ventricular contraction. This, in turn, causes a decrease in myocardial oxygen consumption. NTG has a lesser effect on arterial dilation. Arterial dilation causes a decrease in afterload, the resistance the heart has to pump against to get the blood out of the left ventricle. Decreasing afterload not only decreases myocardial oxygen consumption but also decreases blood pressure.
NTG comes in a variety of preparations: sustained release, transdermal, topical, intravenous, sublingual and spray. The most common preparation used in the United States for an acute anginal attack is sublingual tabs. However, the problem with sublingual tabs is stability and the time it takes the tablet to dissolve, especially when patients are npo.
Stability by far is the biggest concern. Sublingual NTG tabs are required to be stored in airtight, light-protected containers and kept in a dry, cool place. Each time the NTG bottle is opened efficacy potentially decreases. NTG tabs may produce a burning or tingling sensation, but according to the package insert, this should not be considered a reliable method for determining the potency of the tablets. Once the bottle is opened, the shelf life is 3-6 months. Each bottle contains 25-100 tabs and, depending on usage, there is the potential for substantial waste. Additionally, the size of the bottle and the tablets makes it difficult for patients to manipulate. This is of particular concern for the elderly population with arthritic hands and diminished vision.
NTG spray decreases these concerns. The spray is widely accepted as standard of care for acute anginal attacks in Europe. First introduced in the United States in 1983, NTG came in a metal canister, causing concern over fluorocarbons from the pressurized gas in the can.
Recently, the product was repackaged and now comes in a glass bottle with a red plastic coating, minimizing the potential for breakage and allowing the patient to see the amount left in the bottle. The pump-spray action of the dispensing mechanism has eliminated the fluorocarbon concern, making the product environmentally friendly. Each bottle contains 200 sprays and has a shelf life of 2 years.
The NTG spray is immediately absorbed and has eliminated the challenge of dissolving tablets under the tongue, especially in those patients who are npo. Quicker absorption means quicker relief. Like the tabs, the spray can be administered every 5 minutes times three for persistent chest pain. If after three doses there is no relief, the patient should seek immediate medical attention. Each spray is equivalent to 0.4 mg (1/150 grain) tab.
Using the Nitrolingual Spray
The pump spray should be primed prior to the first use. Point the spray away from you and depress the nozzle one time; you will hear a click. Now the pump is ready to go. The pump should be re-primed with one spray if it is not used within 6 weeks.
Each time the spray is used remove the cap. DO NOT SHAKE. Shaking the bottle can cause a displacement of air in the tube, which may cause the measuring chamber to measure the wrong amount, causing an inaccurate dose. Hold the container as close as possible to the mouth. Press the button firmly with forefinger to release the spray onto or under the tongue. DO NOT INHALE SPRAY. Release the button and close mouth. The medication should not be spit out or rinsed out of the mouth for 5-10 minutes following the administration. These steps can be repeated every 5 minutes. A maximum of three doses should be administered prior to seeking additional medical assistance.
Educating the Patient
Patients should be taught how to administer the drug. It should be reinforced that the medication can be administered into the mouth and does not have to be administered under the tongue. Patients should be taught to sit down whenever possible when taking the medication.
Patients should avoid the use of NTG with Viagra® (sildenafil citrate, Pfizer Inc.). Viagra has been shown to potentiate the hypotensive effects of nitrates due to the vasodilatory properties. It is important to instruct patients that alcohol may also enhance the hypotensive effects of NTG. These nitroglycerin-induced hypotensive effects may be accompanied by paradoxical bradycardia and increase angina. The pump spray is about the size of an inhaler and should be available to the patient at all times. This product is not sensitive to light, heat or moisture. Patients may experience a burning sensation in the mouth after the administration of the spray. This is related to the 20 percent alcohol content and has nothing to do with potency or efficacy.
It is important to note that both the AHA Guidelines on Care of the Patient with Chronic Stable Angina and Care of the Patient with Unstable Angina/NSTEMI give a class I recommendation for the use of NTG tabs or nitrolingual pump spray.
Parke-Davis, a Warner-Lambert Division. (2000). Nitrostat package insert. Morris Plains, NJ: Author.
First Horizon Pharmaceutical Corp. (2000). Nitrolingual pumpspray. Roswell, GA: Author.
ACC/AHA. (2000, Sept. 5). ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction. Circulation, 102(10), 1193-1209.
ACC/AHA/ACP-ASIM (1999, June) ACC/AHA/ ACP-ASIM guidelines for the management of pa.tients with chronic stable angina. (1999, June). Journal of the American College of Cardiology, 33(7), 2092-2197.
AnneMarie Palatnik is a clinical nurse specialist at Our Lady of Lourdes Medical Center, Camden, NJ. She also teaches pharmacology for nurses at Our Lady of Lourdes School of Nursing.
Nitroglycerin Spray Nitroglycerin relaxes vascular smooth muscle throughout the body.
Each bottle contains 200 sprays and has a shelf life of 2 years.
The spray is not sensitive to light, heat or moisture.
NTG spray is immediately absorbed and has eliminated the challenge of dissolving tablets under the tongue.
Like the tabs, the spray can be administered every 5 minutes times three for persistent chest pain.
The medication should not be spit out or rinsed out of the mouth for 5-10 minutes following administration.
Immediate medical attention should be sought, if the patient does not receive relief after three doses.
Patients should avoid the use of NTG with Viagra®, which has been shown to potentiate the hypotensive effects of nitrates due to the vasodilatory properties.
Alcohol may also enhance the hypotensive effects of NTG.
Patients may experience a burning sensation in the mouth after the administration of the spray. This is related to the 20 percent alcohol content and has nothing to do with potency or efficacy.