Angina: evolution of the role of nitrates.

In recent years, concern has been expressed over attenuation of therapeutic effect in patients receiving continuous nitroglycerin therapy for the treatment of angina. Studies have shown that exercise tolerance time does not improve with continuous nitroglycerin regimens, although the frequency of anginal attacks may decrease. Intermittent therapy, which incorporates a nitrate-free interval, improves both exercise time and clinical angina. The optimal duration of the nitrate-free interval has yet to be determined. Future research is likely to focus more on supply-side factors in angina. Of the available antianginal drugs, nitrates have been shown to be highly effective coronary vasodilators, particularly in areas of stenosis.