The effect of long-term oral administration of verapamil and metoprolol on arterial pressure, heart rate and plasma catecholamines in hypertensive subjects

Nine patients with varying degrees of hypertension were given, in a random series, 3 x 160 mg verapamil (V), 3 x 100 mg metoprolol (M) per day and a placebo over a period of 4 weeks, after a preliminary period of 4 weeks observation. At the end of each period, bicycle ergometry (50 to 70 watt) was carried out with checks on blood pressure, heart rate, EKG, plasma adrenalin and noradrenaline. A comparison was made between the resting pressure values measured 3 times daily in the last two weeks of treatment, and it was seen that the pressure was statistically significantly reduced from 168/103 to 149/94 by M and from 169/101 to 148/98 by V. There was no significant difference between the preliminary reading and the result with P, nor between M and V. Under exercise, the pressure was reduced from 210/109 to 172/97 with M and from 213/109 to 168/87 mmHg with V. The resting heart rate was clearly reduced by M from 83 to 62/min and slightly by V from 90 to 84/min. Both drugs reduced the rate on exercise significantly: M from 132 to 94, V from 131 to 102/min. The plasma noradrenaline increase on exercise from 269 to 490 ng/l was not significantly altered by either M or V. The plasma adrenalin increase on exercise fell, without statistical significance, in comparison with the preliminary period more definitely under treatment with V. Apart from one case not responding satisfactorily to V treatment, subjective side effects were less with V than with beta blockade. 300 mg M/day and 480 mg V/day reduced the blood pressure in a comparable context. It has therefore to be made clear how far V can be considered to be an alternative to beta receptor blockers in the oral treatment of hypertension.