A Double‐Blind Comparison of Metoprolol CR/ZOK 50 mg and Atenolol 50 mg Once Daily for Uncomplicated Hypertension

Abstract

In a double-blind study with parallel groups, the clinical bioequivalence of the antihypertensive effect of metoprolol CR/ZOK (controlled release formulation) 50 mg and atenolol 50 mg in ordinary tablets given once daily for uncomplicated hypertension was investigated. Clinical bioequivalence was defined as difference in blood pressure reduction less than 8 mmHg. The study involved 195 patients, 98 on metoprolol CR/ZOK and 97 on atenolol. All patients were taken off antihypertensive therapy during a 2-week placebo run-in period. Thereafter the patients were randomly allocated to metoprolol CR/ZOK 50 mg or atenolol 50 mg for 4 weeks. In patients with a diastolic blood pressure remaining above 90 mmHg, the dose was increased to 100 mg daily of the respective drug. After 4 weeks treatment with 50 mg of the two therapies, blood pressure and heart rate was significantly reduced in both treatment groups. At this dose, clinical bioequivalence was found regarding both blood pressure and heart rate reductions. After 8 weeks of therapy (100 mg doses given to 31 in the metoprolol group and 43 in the atenolol group), clinical bioequivalence according to stated definition was found for blood pressures and heart rate reductions, although the reductions of systolic and diastolic blood pressures at rest as well as diastolic blood pressure during exercise were significantly greater in the metoprolol group. In an evaluation of the responder rate after the 8 weeks of treatment, 89% of the patients in the metoprolol CR/ZOK group and 74% in the atenolol group (P less than .05) had a diastolic blood pressure reduction to 90 mmHg or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative Efficacy of Two Different β‐Blockers on 24‐Hour Blood Pressure Control

“…In addition, the longer‐acting metoprolol succinate ER achieves a lower BP over the 24‐hour period compared with shorter‐acting metoprolol tartrate (immediate‐release formulation) 20 . In a previous study comparing once‐daily administration of 50 mg of atenolol and metoprolol succinate, the reductions of SBP and DBP at rest were significantly greater in the metoprolol group 17 . In a separate study, however, no differences were noted in office BP 24 hours after the last dose of 50 mg of atenolol or 100 mg of metoprolol succinate 16 .…”

“…Previous data support the notion that once‐daily atenolol does not provide adequate BP control during the nighttime and early morning periods 14,15 . Studies comparing once‐daily administration of atenolol and metoprolol succinate report either no difference in office BP values after the last dose 16 or lower office BP values with metoprolol, 17 but data from trials using ABPM have not been available. The aim of this study was to evaluate the effects of once‐daily atenolol and metoprolol succinate extended‐release (ER) dosed in the morning on 24‐hour BP control, focusing on nighttime and early morning BP control.…”