Treadmill exercise protocols to demonstrate effectiveness of nitrate drugs in relief of angina pectoris; duration of action and degree of functional enhancement.

During constant uninterrupted exercise with mild angina present, either placebo, nitroglycerin, isosorbide dinitrate or erythrityl trinitrate was given by buccal membrane absorption. Placebo produced no relief and exercise had to be stopped. Nitroglycerin produced rapid complete relief and the long-acting drugs effected relief more slowly but of long duration as shown on repetitive walks as long as 3 h after drug administration.