CLINICAL PHARMACOLOGY OF THE NEW BETA-ADRENERGIC BLOCKING-DRUGS .6. COMPARISON OF PINDOLOL AND PROPRANOLOL IN TREATMENT OF PATIENTS WITH ANGINA-PECTORIS - ROLE OF INTRINSIC SYMPATHOMIMETIC ACTIVITY

Pindolol, a new beta-adrenergic blocking drug with intrinsic sympathomimetic activity, and propranolol were given in increasing equipotent doses (pindolol: 2.5 to 10 mg. every 6 hours; propranolol: 10 to 40 mg. every 6 hours) over 12 weeks in a double-blind randomized trial to 41 patients with angina pectoris. The drugs were then gradually withdrawn over a two week period. With maximum doses, both pindolol and propranolol increased exercise capacity, compared to control, on multistage treadmill testing (pindolol: 8.0 ± 0.4 to 9.7 ± 0.3 mets, p < 0.01; propranolol: 8.0 ± 0.4 to 9.6 ± 0.3 mets, p < 0.05). At each exercise level both pindolol and propranolol decreased the heart rate, systolic blood pressure, and rate-pressure product (HR × BP). At the 9 met exercise level, the HR × BP decreased from 17,420 ± 850 to 13,205 ± 510 mm. Hg min.-1 with pindolol (p < 0.002); with propranolol; 18,106 ± 440 to 13,205 ± 480 mm. Hg min.-1 (p < 0.01). At the same level the magnitude of exercise-induced ECG ST depression decreased from 1.3 ± 0.3 to 0.4 ± 0.15 mm. with pindolol (p < 0.05), and from 1.3 ± 0.3 to 0.8 ± 0.2 mm. with propranolol (p < 0.05). Both drugs reduced the number of spontaneous attacks of angina pectoris per week. Pindolol did not appreciably decrease the resting heart rate (66.8 ± 1.9 vs 64.6 ± 1.2) or HR × BP (8,254 ± 418 vs 7,651 ± 210 mm. Hg min.-1 in contrast to propranolol, which reduced both (heart rate: 70.5 ± 2.2 to 62.2 ± 2.4, p < 0.01; HR × BP: 8,677 ± 423 to 7,338 ± 455 mm. Hg min.-1, p < 0.005). In addition, pindolol slightly increased the echocardiographically estimated ejection fraction at rest (0.59 ± 0.02 to 0.62 ± 0.02, p < 0.02), while propranolol depressed it (0.57 ± 0.02 to 0.51 ± 0.01, p < 0.04). Both pindolol and propranolol could be safely withdrawn over a gradual two week withdrawal interval. © 1979.