A reappraisal of nitrate therapy.

Nitroglycerin and the long-acting nitrates are beneficial in stable and unstable angina pectoris and acute myocardial infarction and as adjunctive therapy in congestive heart failure. Nitroglycerin compounds relax vascular smooth muscle, producing venous, arterial, and arteriolar dilatation. These actions are modulated by stimulation of intracellular cyclic guanosine monophosphate. Nitrate efficacy in ischemic heart disease is due to peripheral venous and arterial vasodilatation that results in decreased myocardial oxygen consumption. Nitrates also dilate coronary arteries and collaterals, reverse coronary vasoconstriction, and enlarge some coronary atherosclerotic lesions. Nitrates improve exercise performance in stable angina pectoris. Intravenous nitroglycerin should be used in the initial treatment of unstable angina. Nitrates may be beneficial in myocardial infarction for control of ischemic pain, acute hypertension, and left ventricular failure. In subjects with congestive heart failure, nitrates reduce symptoms and improve exercise tolerance. Nitrate tolerance is a problem with continuous nitrate therapy. Tolerance is most likely to occur with frequent dosing or the use of long-acting nitrates, particularly transdermal nitroglycerin disks, and can be prevented or reversed with intermittent-dosing regimens.