Dihydropyridine and nondihydropyridine
calcium channel blockers (CCB) differ in pharmacologic characteristics. Few clinical studies distinguish effects of CCB as monotherapy. We conducted a comprehensive comparison of two CCB on patients with moderate to severe
hypertension. Thirty patients with pretreatment diastolic blood pressures > or = 100 mm Hg were randomly assigned to either
nifedipine-GITS or
verapamil-SR. Dose titration achieved a diastolic blood pressure of < or = 95 mm Hg or a decrease of > or = 15 mm Hg over 4 weeks. Clinic blood pressure (BP), 24-h ambulatory BP, exercise BP, left ventricular mass, systolic and diastolic function by echocardiography, and coronary flow reserve by split-dose
thallium-201 imaging with
adenosine were assessed at baseline, end of titration, 3 months and 6 months of treatment. Plasma
renin activity,
atrial natriuretic peptide,
norepinephrine, and
epinephrine were assayed. Both drugs caused similar reductions in clinic and 24-h ambulatory BP and similar reductions in left ventricular mass index. Compared to
nifedipine-GITS,
verapamil-SR produced a significantly lower resting and peak exercise heart rate.
Nifedipine-GITS elicited a lower peak exercise systolic BP. At end titration
nifedipine-GITS produced lower plasma
atrial natriuretic peptide levels, no longer apparent by 6 months. Plasma
norepinephrine was lower with
verapamil-SR, also at end titration and at 3 months, but not at 6 months. Plasma
epinephrine and plasma
renin activity were unchanged by either drug. There was no difference for systolic or diastolic left ventricular function or coronary flow reserve between the two treatments. Once daily
nifedipine-GITS and
verapamil-SR are equally effective for reduction of arterial pressure in moderate to severe
hypertension. Differences in their hemodynamic profiles and neurohormonal responses are consistent with preclinical pharmacologic characteristics. The clinical implications of their similarities and differences remain to be fully evaluated in outcome studies.