A CONTROLLED STUDY ON THE ANTIHYPERTENSIVE EFFECT OF A NEW β‐ADRENERGIC RECEPTOR BLOCKING DRUG, METOPROLOL, IN COMBINATION WITH CHLORTHALIDONE

A double-blind crossover evaluation of the antihypertensive effect of metoprolol v. placebo was carried out in a series of twenty-three patients with mild or moderate essential hypertension who were receiving chlorthalidone (25 mg daily) as their basic treatment. An individually titrated metoprolol dosage (75-300 mg) was used. The double-blind crossover study consisted of two 3-month periods during which the patients received either metoprolol or placebo in addition to chlorthalidone. Metoprolol, as compared with placebo, produced a statistically significant reduction of blood pressure, both in supine and standing positions. Normotension was achieved during metoprolol-chlorthalidone treatment in twenty-two of the twenty-three patients, but during placebo-chlorthalidone treatment in only twelve of the twenty-three patients. During the double-blind crossover study mild side-effects occurred during metoprolol-chlorthalidone treatment in fourteen patients during first month, in twelve patients during second month and seven patients during third month. During placebo-chlorthalidone treatment side effects occurred in seven, six and seven patients, respectively. In conclusion, metoprolol caused a significant fall in blood pressure when given to patients already receiving chlorthalidone. Metoprolol in combination with chlorthalidone appears to be an effective and well-tolerated treatment for mild and moderate hypertension in those patients not responding to chlorthalidone alone.