Promise and Perils of Drugs in Stable Angina: Nitrates

Venous pooling and after-load reduction are commonly believed to be the most important mechanism for the anti-anginal activity of nitrates. Recent studies were able to demonstrate a beneficial effect of nitrates on the coronary vasomotor tone. Very small doses of nitroglycerin increase the diameter of epicardial vessels and, most importantly, the diameter of the arteriosclerotic lesion itself. The effectiveness of nitroglycerin patches may also be related to the coronary component of the mechanism. Controversy exists with regard to the long-term effect of nitrates since some authors have demonstrated nitrate tolerance. In clinical practice tolerance has not created major problems so far but further studies are needed to resolve the conflicting evidence produced by different groups of workers.