[Anti-anginal effect of transdermally applied nitroglycerin as dependent on the size of the plaster]

Nitroglycerin plaster (in 5 cm2, 10 cm2 or 20 cm2 sizes) was applied to 12 patients with coronary heart disease, angina and exercise-induced ischemic reactions in the course of a simple-blind trial with intra-individual crossover in a randomized sequence over one week each. A 15 cm2 plaster served as a placebo. In the placebo phase the mean number of angina attacks was 9.3 per week. It decreased to 6.2 with the 10 cm2 plaster (P less than 0.05), to 2.6 per week with the 20 cm2 plaster (P less than 0.001). The ischemia reaction in the exercise ECG (sum of ST segment depressions), recorded on day 7 of the treatment phase, was improved three hours after plaster application, dependent on the size of the plaster: placebo 6.0 +/- 1.2 mm; 5 cm2 plaster 5.1 +/- 1.0 mm; 10 cm2 4.6 +/- 1.0 mm (P less than 0.05); 20 cm2 3.4 +/- 0.9 mm (P less than 0.001). The angina-free period during ergometry showed dose-dependent improvement 3 and 24 hours after application. Arterial blood pressure was decreased only after 20 cm2 plaster by 8% after three hours, as compared with the placebo (P less than 0.05). There was no effect on heart rate, at rest or on exercise, after any plaster. The results indicate that significant decrease in ischemia reaction occurred with a plaster of 10 cm2 or larger. A 24-hour effect was demonstrable only with respect to the duration of symptom-free exercise.