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"Nitroglycerin" or "nitroglycerine" (NTG) is a drug taken to treat chest pain, which is often referred to in medical terms as angina pectoris or angina. This medication is one of the cardiac nitrate drugs that are used to treat angina by dilating the coronary arteries to increase blood flow and oxygen to the heart muscle. Nitroglycerin is available in almost every conceivable form but is best known publicly for its tiny sublingual tablets that are placed and absorbed under the tongue. A sufficient nitroglycerin dose is one that relieves a patient's angina, prevents heart damage due to low oxygenation or myocardial ischemia, and avoids undue side effects. Due to the number of ways it can be administered, an adequate nitroglycerin dose also varies according to the administration route, the degree of coronary artery blockage, the degree of stress placed on the heart that prompted the anginal episode, and other issues.
The first factor determining an adequate nitroglycerin dose is the administration route. Nitroglycerin can be taken in a variety of ways, such as by ointment, patches, sublingually, orally in an extended release capsule, orally or nasally in aerosol form, and intravenously. All of these types of nitroglycerin administration are used to increase cardiac perfusion and oxygenation by dilating the coronary arteries, although some routes are used under different circumstances. Intravenous nitroglycerin, extended-release capsules, ointments and patches are used on a prophylactic basis to prevent anginal attacks. Sublingual and oral or nasal aerosol nitroglycerin routes are used to treat and relieve episodes of acute angina on an as-needed basis.
Another factor that influences whether a given nitroglycerin dose effectively relieves acute angina is the extent of coronary artery blockage and the number of arteries affected by coronary artery disease. Higher or repeated doses might be necessary for patients with advanced coronary artery disease in order to perfuse the heart with adequate blood and oxygen. The degree of stress involved in incurring the anginal episode might also be a factor in determining a sufficient nitroglycerin dose. For example, walking up a flight of steps carrying a bag of groceries requires more exertion than watching a television show in a recliner and might require a higher or repeated nitroglycerin dose than angina occurring at rest.
Sublingual nitroglycerin doses necessary to relieve angina are also influenced by the age of the pills or the medication's exposure to heat or light. Previous or repeated use of nitroglycerin also decreases its efficacy as the medication has less effect on the coronary arteries. Geriatric patients are considered to be at higher risk of nitroglycerin side effects, particularly hypotension, and may use smaller treatment doses. Finally, nitroglycerin interacts with many different types of medications. These interactions often require dosing readjustments for either one or more medications.