Which medications in the drug class Nitrates, Angina are used in the treatment of Unstable Angina?

Updated: Oct 01, 2020
  • Author: Walter Tan, MD, MS; Chief Editor: Eric H Yang, MD  more...
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Nitrates, Angina

Nitrates are vasodilators that relieve chest discomfort (angina) by improving myocardial oxygen supply, thereby, in turn, dilating epicardial and collateral vessels and thus improving blood supply to the ischemic myocardium. Vasodilators oppose coronary artery spasm, which augments coronary blood flow and reduces cardiac work by decreasing preload and afterload.

These drugs are effective in the management of symptoms in acute MI but may reduce mortality only slightly. Nitroglycerin can be administered sublingually by tablet or spray, topically, or intravenously (IV). In acute MI, topical administration is a less desirable route because of unpredictable absorption and the onset of clinical effects.

Nitroglycerin IV

Nitroglycerin causes relaxation of vascular smooth muscle by stimulating intracellular cyclic guanosine monophosphate production. Whether administered topically, sublingually, orally, or IV, nitrates ameliorate several pathways of unstable angina and reduce the incidence of symptomatic ischemia. Nitrates lower systemic arterial pressure and decrease venous return to the heart, both of which reduce myocardial wall stress. Similarly, nitrates are excellent coronary vasodilators.

Other possible beneficial effects include a transient inhibition of platelet aggregation, an increase in coronary collateral blood flow, and a favorable redistribution of regional flow. Notably, induction of heparin resistance has been reported.

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