LONG-TERM EFFECTS OF ISRADIPINE ON BLOOD-PRESSURE AND RENAL-FUNCTION

The hemodynamic and renal effects of isradipine were investigated in 10 hypertensive patients treated for 3.5 months and in a further nine patients treated for two years. Both groups achieved significant and sustained reductions in systolic blood pressure/diastolic blood pressure (−15 percent/−12 percent and −15 percent/−20 percent, respectively; p < 0.001). Renal parameters were investigated two to three hours after the morning dose of isradipine, using a water-loading procedure. After 3.5 months of treatment, the glomerular filtration rate and renal plasma flow showed small increases (+6 percent and +9 percent, respectively, p < 0.05), whereas, after two years, these changes were no longer present (+4 percent and 0 percent). Clearance of sodium and uric acid was increased by 40 percent (p < 0.01) and 21 percent (p < 0.01), respectively, after 3.5 months, and by 45 percent (p < 0.05) and 23 percent (p < 0.01), respectively, after two years. Lithium clearance studies revealed the natriuretic effect to be located in the proximal tubule. After 3.5 months, a significant relationship was found between the blood pressure response and the change in sodium excretion, but this relationship also was no longer present after two years. In conclusion, because of a maintained blood pressure-lowering effect while preserving renal function, and sustained natriuretic and uricosuric actions, isradipine can be considered a promising agent in the long-term treatment of arterial hypertension.