The antianginal efficacy of nitroglycerin (NTG), given in a new transdermal therapeutic system (TTS), was compared with that of nifedipine and verapamil, both in slow-release (SR) formulation, in a randomized, double-blind, placebo-controlled study, carried out in 8 patients with stable exercise-induced angina pectoris. TTS NTG 40 cm2 (releasing 20 mg of NTG over 24 hours), nifedipine 20 mg SR, verapamil 120 mg SR and placebo were given once on 4 consecutive days according to a 4 X 4 latin-square design, twice replicated. A cycloergometric symptom-limited exercise test was performed 4 and 8 hours after the administration of each drug. Four hours post-dosing, mean exercise duration was 407 sec. after placebo and 523 (+28%) and 485 (+ 19%) sec. after TTS NTG and nifedipine SR respectively, while at the 8th hour it was 375 sec. after placebo, and 515 (+ 37%) and 457 (+ 21%) sec. after TTS NTG and nifedipine SR. Exercise duration after verapamil was similar to that after placebo. In comparison with placebo maximal workload and total work performed were significantly higher on TTS NTG and on nifedipine at both times of observation, but no significant differences were seen after verapamil. Peak exercise systolic blood pressure was nearly identical after all the treatments tested. Peak exercise heart rate and pressure rate product were both significantly higher on TTS NTG, as well as on nifedipine, in comparison with placebo, while values after verapamil did not differ from those after placebo.(ABSTRACT TRUNCATED AT 250 WORDS)