Slow release oxprenolol in angina pectoris: study comparing oxprenolol, once daily, with propranolol, four times daily.

Oxprenolol and propranolol are noncardioselective beta adrenoreceptor blocking agents known to be equally effective in the management of patients with angina pectoris. Both are usually prescribed four times daily. Slow release formulation of oxprenolol administered once daily has been shown to maintain therapeutic effects for 24 hours. In a double-blind crossover study in 23 patients with stable angina pectoris, the effects of 160 mg slow release oxprenolol, administered once daily for 1 month, were compared with those of 40 mg of propranolol given four times daily for a similar period. No adverse effects occurred when patients were switched between treatment schedules. The average number of anginal attacks experienced were 11/month during oxprenolol therapy and 8/month during propranolol therapy (difference not significant). The resting values for heart rate were higher 7 1/2 nd 24 hours after oxprenolol than they were 4 and 12 hours after propranolol (p less than 0.01). The treadmill walking time to the onset of angina and to the development of moderate angina 24 hours after oxprenolol was less than that observed 7 1/2 hours after the drug or 4 and 12 hours after propranolol (p less than 0.01). In contrast, the values for walking time to the onset of angina and to the development of moderate angina at 4 and 12 hours after propranolol were similar. This decreased exercise tolerance 24 hours after oxprenolol was associated with a lesser degree of beta adrenoreceptor blockade than that present after propranolol as documented by higher levels of heart rate (p less than 0.05), systolic blood pressure (p less than 0.05) and rate-pressure product (p less than 0.05) during exercise after oxprenolol therapy. It is concluded that in the doses used, slow release oxprenolol administered once daily does not exert as consistent a beneficial effect on exercise tolerance throughout the dosing schedule as does propranolol given four times daily.