Transdermal Nitroglycerin Patches in Angina Pectoris

The duration of effect of transdermal nitroglycerin patches was studied in 14 patients with angina pectoris. By titrating the dose to achieve specific circulatory effects, we chose a patch size that produced a consistent fall in systolic blood pressure of 10 mm Hg or greater for each patient (10 cm2 in 7 patients, 20 cm2 in 5, and 40 cm2 in 2; releasing 5, 10, and 20 mg of nitroglycerin per 24 hours, respectively). The effects of these individualized patches were compared with those of placebo patches. Compared with placebo, nitroglycerin patches increased exercise duration to the onset of angina (257 +/- 72 compared with 383 +/- 130 seconds, p less than 0.0001) and total exercise time (338 +/- 89 compared with 456 +/- 119 seconds, p less than 0.0001) and decreased ST segment depression (1.0 +/- 0.5 compared with 0.6 +/- 0.4 mm, p less than 0.05) at 4 hours but not at 24 and 48 hours. We conclude that nitroglycerin patches do not show objective evidence of antianginal or antiischemic effects for 24 hours. Tolerance to the circulatory and antianginal effects probably develops within 24 hours of patch application.