Antihypertensive and metabolic effects of diltiazem and nifedipine.

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Abstract
The antihypertensive effect of diltiazem (180-270 mg/day) and nifedipine (40-60 mg/day) in slow-release forms was assessed over 8 weeks in a double-blind parallel study in 40 subjects with essential hypertension at rest and during exericse. Blood pressure was comparably reduced in both groups at rest as well as during exercise. The responder rates (.gtoreq. 10% reduction in diastolic blood pressure) after 8 weeks of therapy were 53% at rest and 75% during exercise in the diltiazem group and 78% and 50%, respectively, in the nifedipine group. Diltiazem decreased heart rate by 8% (p < 0.01), while nifedipine did not affect it. As a consequence, myocardial oxygen consumption, as judged by the pressure-rate product, was reduced by diltiazem. Resting plasma norepinephrine levels were increased significantly after 8 weeks of diltiazem therapy. Plasma epinephrine, renin aldosterone, glucose, insulin, and lactate and routine laboratory parameters were unchanged at the end of the study. No significant changes in total cholesterol and triglyceride levels were observed after 8 weeks. Whereas therapy with diltiazem resulted in an 8% fall in low density lipoprotein cholesterol after 8 weeks (p < 0.05), nifedipine induced a drop in very low density lipoprotein cholesterol (p < 0.05) after 8 weeks of therapy. We conclude that both diltiazem and nifedipine are effective antihypertensive agents lacking undesirable metabolic side effects. Diltiazem, however, had the advantage of lowering heart rate and myocardial oxygen consumption.