Calcium antagonists are
vasodilators and, therefore, they decrease the peripheral vascular resistance. Acute vasodilation invokes a reflex increase in sympathetic activity that results in positive chronotropic and inotropic effects. These acute effects have been demonstrated both in patients with
hypertension and subjects with normal blood pressure values. A theoretic objection to the use of
nifedipine as monotherapy in patients with chronic
hypertension was that
calcium channel blockers would invoke a chronic sympathetic response and, in particular, chronic
tachycardia. In this study, the effects of
calcium antagonists on ambulatory blood pressure were investigated in patients with
essential hypertension who had no evidence of target organ damage. Direct arterial blood pressure measurements, monitored continuously over 24 hours, showed that
nifedipine significantly reduced systolic and diastolic blood pressures throughout the day and at night. The variability in blood pressure values was not altered by
nifedipine therapy, nor were there significant changes in heart rate. Estimations of left ventricular mass also demonstrated that successful control of blood pressure with
nifedipine monotherapy resulted in a significant reduction in the left ventricular mass similar to that achieved with beta blockers and
diuretics. Thus,
nifedipine may be used effectively as monotherapy in patients with
essential hypertension, controlling blood pressure throughout the day and at night.
Calcium antagonists are, therefore, useful drugs in the management of
hypertension and, in light of the findings reported herein, should be seriously considered as initial
therapy.