Long-term renal effects of isradipine, a calcium entry blocker, in essential hypertension

The long-term effects (9 weeks) on renal hemodynamics of the new calcium entry blocker isradipine (PN 200-110) were assessed in 20 middle-aged male patients with essential hypertension. The study was double-blind placebo-controlled with a crossover design. Isradipine or placebo tablets were titrated from 2.5, 5, and 7.5 mg b.i.d. every 3rd week to achieve a diastolic blood pressure of less than or equal to 90 mm Hg. The renal parameters were assessed 2-4 h after dosing. Despite a decrease in diastolic blood pressure (91 vs. 104 mm Hg, p less than 0.001) the renal plasma flow increased (465 vs. 394 ml/min, p less than 0.05). The glomerular filtration rate was unchanged and the filtration fraction was reduced (0.21 vs. 0.23, p less than 0.05). The plasma renin activity increased (0.71 vs. 0.51, p less than 0.05). The patients probably did not retain sodium because the body weight was unchanged. Rather, long-term treatment with isradipine was associated with a repetitive postdose increase in natriuresis (0.45 vs. 0.34 mmol/min, p = 0.06).