Nitroglycerin (NTG), also known as glycerine trinitrate (GTN) is a nitrate medication typically administered to relieve anginal chest pain and manage blood pressure through vasodilation. Different preparations of nitroglycerin may also be administered for treatment of renal issues, liver issues and even as an ointment for anal fissures or tears. Show Nitroglycerin can be administered through a wide variety of methods, including: When administering spray nitroglycerin, beware not to accidentally inhale the medication. (Photo/Rommie Duckworth)
Names and dosages vary depending on the route of administration. This article will concentrate on the forms of nitroglycerin most commonly encountered by EMS; sublingual tablets and sprays, transdermal paste, transdermal patches and IV infusions. Nitro administration routesNitroglycerin dosage, administration routes and trade names include:
The forms of nitroglycerin typically administered by EMS providers of different levels include sublingual tablets or sprays; transdermal paste; and, for some advanced providers, IV nitroglycerin solutions. The forms of nitroglycerin used by patients typically encountered by EMS providers in the field include sublingual tablets or sprays and transdermal patches. Nitroglycerin mechanism of actionNitroglycerin 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. 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. IV solutions of nitroglycerin may be administered for a variety of purposes, but are most commonly used by EMS providers for patients who are intolerant of or unresponsive to sublingual nitroglycerin, or who require higher doses of nitroglycerin than can be provided sublingually or transdermally. Desired effects and indications of nitroglycerinVasodilation decreases myocardial preload and afterload as well as decreasing blood pressure. This decrease in pressure reduces the workload of the heart and helps to relieve heart failure. For EMS providers, typical nitroglycerin indications include chest pain or discomfort associated with angina pectoris or suspected acute myocardial infarction, as well as pulmonary edema with hypertension. For patients at home, indications typically include prevention or treatment of chest pain, or discomfort associated with angina pectoris or suspected acute myocardial infarction. Contraindications of nitroglycerinABSOLUTE: Discontinue nitroglycerin administration or do not administer nitroglycerin to patients who:
RELATIVE: Nitroglycerin administration may be considered with caution to patients who:
Nitroglycerin side effects include:
Nitroglycerin precautions:
Nitroglycerin myths and misconceptionsLike many commonly encountered prehospital treatments, some of the common knowledge surrounding nitroglycerin contains more myths and misconceptions than evidence-based facts. Here are some of the top myths and misconceptions about nitroglycerin treatment:
Take the opportunity to share this article with your fellow providers. Powerful treatments like nitroglycerin demand well-informed responders. Listen for more: Serial killers: Acute chest pain This article was originally posted Jan. 3, 2018. It has been updated. |