Influence of Time and Physical Activity on Blood Pressure and Heart Rate during Treatment with β‐Blocking Agents Once Daily

In a cross-over study of 52 middle-aged patients with mild to moderate essential hypertension, we have compared the effect and tolerability of 100 mg atenolol and 100 mg metoprolol given once daily. After 1 1/2 and 3 months of treatment, both systolic and diastolic blood pressure 24 hours after drug intake were significantly lower on atenolol. There were no significant differences after 3 months when blood pressure was read 3-4 hours after dose intake. During exercise, systolic blood pressure and heart rate were--at all work-loads--significantly lower on atenolol. Four patients on metoprolol and one patient on atenolol discontinued treatment owing to side-effects. The results support the need for thorough analysis of the duration of action and influence of physical activity and sympathetic tone in comparisons between presumedly equivalent antihypertensive drugs.