Metoprolol and atenolol administered once daily in primary hypertension. A clinical comparison of the efficacy of two selective beta-adrenoceptor blocking agents.

To compare the antihypertensive effect of two beta-blocking agents, metoprolol (Seloken) and atenolol (Tenormin), a double-blind study was performed in 55 patients. Following a six-week placebo period the patients, who all had mild to moderate essential hypertension (WHO I-II), were randomly allocated to treatment with either metoprolol (n = 28) or atenolol (n = 27). During a six-week period they received 100 mg of either drug once daily. For patients who at the end of that period did not reach a diastolic blood pressure (BP) of less than 95 mmHg the daily dose was increased to 200 mg. Patients who responded (diastolic BP less than 95 mmHg) continued on the initial dosage regimen. When comparing the two groups with regard to the reduction of BP, there was no difference either 24 hours after the last dose or 5-9 hours after drug administration. The decrease in supine systolic/diastolic BP was 18/16 mmHg on metoprolol and 20/16 on atenolol. The decrease in heart rate was comparable in the two groups. Eight patients in the metoprolol and 7 in the atenolol group had their dose increased to 200 mg at the end of the first six-week period. This means that the number of patients not responding to 100 mg daily was comparable in the two groups. We did not observe any differences in side-effects of the two drugs. The results clearly suggest that atenolol and metoprolol are equipotent following once daily administration in patients with mild to moderate hypertension.