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Back one screen: left arrow Back to main menu: ESC MECHANISMS OF ANTIANGINAL DRUGS * Nitrates: The nitrates cause selective smooth muscle relaxa- tion, probably by release of the nitric oxide (NO) group, which apparently increases cGMP. There is little direct ef- fect on myocardial or skeletal muscle. In atherosclerotic angina, the major therapeutic mechanism is reduction of car- diac work by peripheral vasodilatation, especially of the veins. In vasospastic and unstable angina, in which coronary vasospasm may be a major contributor to the relative ischemia of the tissue, these drugs may also produce useful coronary vasodilatation. * Beta-adrenoceptor blockers (see Chapter 5): Beta blockers decrease cardiac work by blocking beta-1 receptors in the myocardium and thereby decreasing cardiac output. They also reduce cardiac work by decreasing blood pressure. Although only 2 members of this group (both nonselective beta block- ers) have been approved for use in angina at the time of this writing, all beta-1 selective and nonselective beta blockers are effective in atherosclerotic angina. These drugs do not cause vasodilatation. (PgDn key for more text) * Calcium channel blockers: These agents directly cause peripheral vasodilatation and directly reduce cardiac work by reducing influx of activator calcium into smooth muscle and cardiac cells. In vasospastic and unstable angina, these drugs may cause a useful degree of coronary vasodilatation. References: 1. Symposium: Circulation 1985; 72 (Suppl V). 2. Takaro T et al: The Veterans Administration Cooperative Study of Stable Angina: Current status. Circulation 1982; 65 (Suppl 2): 60. 3. Gersh B J et al: Comparison of coronary artery bypass surgery and medical therapy in patients 65 years of age or older. N Engl J Med 1985;313:217. 4. Morse JR, Nesto RW: Double-blind crossover comparison of the antianginal effects of nifedipine and isosorbide dinitrate in patients with exertional angina receiving propranolol. J Am Coll Cardiol 1985; 6: 1395. (Home to go to start of file, PgUp to scroll up)


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