South African multicentre study of metoprolol and propranolol in essential hypertension

Ninety-three patients diagnosed as essential hypertensives, WHO stage I or II, entered this double-blind trial comparing 2 dose levels of CGP 2175-H 93/26 (metoprolol) with 2 doses of propranolol. Treatment on active medication was maintained for 6 weeks and was started after a 2-week washout and a 2-week placebo period. Twelve patients dropped out of the trial for reasons not related to the drugs and 1 patient was regarded as a therapeutic failure. Efficacy was assessed by measuring the diastolic and systolic blood pressure, pulse rate and by noting any significant ECG changes. All treatments reduced and maintained a lower blood pressure. However, a reduction with 360 mg propranolol per day was not statistically significant. Metoprolol 120 mg/d was significantly superior to propranolol 240 mg/d in holding the diastolic supine blood pressure at less than or equal to 90 mmHg. Metoprolol 120 mg/d and 210 mg/d pooled results were significantly superior to the propranolol 240 mg/d and 360 mg/d pooled data in maintaining a diastolic blood pressure of less than or equal to 90 mmHg. All treatments were well tolerated and in no case was it necessary to withdraw owing to adverse effects. No significant difference was detected between the treatments with respect to therapeutic emergent symptoms and signs. Laboratory results remained normal with all treatments.