Effect of partial agonist activity on the side effects of beta-blockade in patients with chronic stable angina

Some side effects of the beta 1-adrenoceptor blocker atenolol may result from depression of cardiac output at rest. They may, therefore, be reduced by the use of drugs with beta 1-partial agonist activity, such as epanolol. We compared once-daily atenolol 100mg and epanolol 200mg in 20 patients reporting side effects while taking atenolol for chronic stable angina. A double-dummy, double-blind, crossover design was used to assess side effects by use of visual analogue scales and interviews, and antianginal efficacy by treadmill exercise tests and diary cards. In a comparison with atenolol, no significant differences in exercise time (686 +/- 11 seconds vs 685 +/- 10 seconds, maximum ST depression (1.02 +/- 0.09mm vs 1.07 +/- 0.08mm), time to 1mm ST depression (8.4 +/- 1.9 minutes vs 9.0 +/- 2.0 minutes), or days without angina (median 100% in both) were shown. All visual analogue scores were higher with epanolol (subjective energy 58.3 +/- 1.7 vs 54.3 +/- 1.5, well-being 61.8 +/- 1.8 vs 58.6 +/- 1.5 and warmth of extremities 68.4 +/- 3.6 vs 62.0 +/- 3.1). Although these differences did not attain statistical significance, 11 patients expressed a preference for epanolol and only 6 for atenolol. We conclude that, in this study, epanolol is as effective as atenolol as an antianginal agent for chronic stable angina. It improved the side effect profile in some but not all patients.