Antihypertensive and metabolic effects of long-term therapy with nifedipine slow-release tablets.

Sixteen nonhospitalized men, average age 41.3 years with essential hypertension (WHO I-II) were given nifedipine slow-release tablets of 20 mg twice daily for 48 weeks. Both supine and standing blood pressure values were significantly reduced, but heart rate was not significantly changed by the drug. A significant decrease in serum sodium and potassium was found. A slight increase in serum magnesium throughout the study became statistically significant at 48 weeks (p less than 0.05). It is suggested that a possible diuretic activity, and the increase in magnesium, may add to the direct nifedipine-induced blood pressure reduction. Serum creatinine increased significantly after 24 and 48 weeks of nifedipine administration; serum urea, cholesterol, triglycerides, uric acid, and blood glucose remained essentially unchanged. Most of the patients had low plasma renin activity (PRA) in the control period, and nifedipine significantly increased PRA. Body weight was kept constant. Side effects were few and of no clinical significance. The slow-release preparation of nifedipine seems to be a potent and effective drug in treating essential hypertension of a mild to moderate degree.