Effects of nifedipine, verapamil and diltiazem on renal function

Eight healthy female volunteers were given single doses of nifedipine 10 mg, verapamil 80 mg, diltiazem 120 mg or placebo on 4 different study days. Urine and sodium output increased after all four drugs, but the increase after nifedipine was significantly greater than after verapamil or placebo. Nifedipine caused a significant increase in heart rate; none of the drugs caused any change in blood pressure. Potassium excretion, creatinine clearance, free water clearance and plasma renin activity did not change with any drug. The mechanism of the natriuresis and diuresis has still to be elucidated.