Before prescribing, providers should determine if the patient is taking any medications that may interact with nitroglycerin. Common interactions include alteplase, heparin, tricyclic antidepressants, and other anticholinergic drugs. Alcohol intake should also be limited. Nitroglycerin is pregnancy category C, and its use requires caution in breastfeeding mothers. It is not currently known whether nitroglycerin is excreted in breast milk. Overdose toxicity from nitroglycerin is mainly a consequence of increased vasodilatory response.
Hypotension, venous pooling, increased vasodilation, and reduced cardiac output can be expected in these patients. Compensatory effects, such as tachycardia and palpitations, can also be expected. Vasodilation and venous pooling can increase the amount of blood in the cranial space, resulting in increased intracranial pressures; this can cause persistent, throbbing headaches, along with confusion, fever, vertigo, nausea, vomiting, and visual disturbances.
No currently known antagonist is available to counteract the effect of nitroglycerin. Since the effects are related to venodilation and relative arterial hypovolemia, efforts to increase central fluid volume have proven effective. Intravenous administration of normal saline, in addition to the passive elevation of the patient's legs, may provide adequate support, but there are no controlled trials to prove its effectiveness.
Epinephrine or other arterial vasoconstricting agents are not recommended as they will not likely improve the patient's condition and may cause more difficulties in the future. Methemoglobinemia has some rare reports as a consequence of nitrate overdose. Clinician suspicion should be raised in patients with hypoxemia symptoms despite a lack of respiratory symptoms, normal arterial PO2, and adequate cardiac output. Blood from patients with methemoglobinemia has a "chocolate brown" appearance in color, with no change in color upon exposure to air.
Interprofessional team members including clinicians, cardiology specialists, primary care providers, pharmacists, internists, and nursing staff who work with patients taking nitroglycerin should be fully aware of the indications and contraindications of the drug, as well as the potential adverse effects. Overall, nitroglycerin is relatively safe, and monitoring of the levels is not required.
Pharmacists can assist the team by monitoring for drug-drug interactions. It is currently unknown whether nitroglycerin is excreted in breast milk. Interprofessional collaboration and information sharing will drive better outcomes with fewer adverse events with nitroglycerine therapy. Parratt JR, Nitroglycerin--the first one hundred years: new facts about an old drug.
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Permissions Icon Permissions. Abstract The effect of nitroglycerin NTG is mainly a reduction in preload and afterload. Nitroglycerin , afterload , arterial compliance , total systemic resistance , systolic resistance. Issue Section:. You do not currently have access to this article. Download all slides. Sign in Don't already have an Oxford Academic account?
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At high concentrations, excessive systemic vasodilation may lead to hypotension and a baroreceptor reflex that produces tachycardia. Furthermore, tachycardia, by reducing the duration of diastole , decreases the time available for coronary perfusion, most of which occurs during diastole click here for more details.
The primary pharmacologic action of nitrodilators, arterial and venous dilation, make these compounds useful in the treatment of hypertension, heart failure, angina and myocardial infarction. Another beneficial action of nitrodilators is their ability to inhibit platelet aggregation. Nitrodilators are not used to treat chronic primary or secondary hypertension ; however, sodium nitroprusside and nitroglycerine are used to lower blood pressure in acute hypertensive emergencies that may result from a pheochromocytoma, renal artery stenosis, aortic dissection, etc.
Nitrodilators may also be used during surgery to control arterial pressure within desired limits. Nitrodilators are used in acute heart failure and in severe chronic heart failure. Arterial dilation reduces afterload on the failing ventricle and leads to an increase in stroke volume and ejection fraction. Furthermore, the venous dilation reduces venous pressure, which helps to reduce edema. Reducing both afterload and preload on the heart also helps to improve the mechanical efficiency of dilated hearts and to reduce wall stress and the oxygen demands placed on the failing heart.
Organic nitrates are used extensively to treat angina and myocardial infarction. They are useful in Printzmetal's variant angina because they improve coronary blood flow i.
They are important in other forms of angina because they reduce preload on the heart by producing venous dilation, which decreases myocardial oxygen demand. It is unclear if direct dilation of epicardial coronary arteries play a role in the antianginal effects of nitrodilators in chronic stable or unstable angina. These drugs also reduce systemic vascular resistance depending on dose and arterial pressure, which further reduces myocardial oxygen demand.
Several different nitrodilators are available for clinical use: Go to www. The nitrodilators listed above differ in the route of administration, onset of action, and duration of action. Nitroglycerin , which has been used since the 19th century, is commonly used in the treatment of angina because it is very fast acting within 2 to 5 minutes when administered sublingually. Its effects usually wear off within 30 minutes. Therefore, nitroglycerin is particularly useful for preventing or terminating an acute anginal attack.
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