Intravenous isradipine in the management of severe hypertension in pregnant and nonpregnant patients. A pilot study.

To determine the appropriate dosage regimen of isradipine in black patients with severe hypertension of pregnancy, 10 patients (gestational age, 30 to 38 weeks; diastolic blood pressure [DBP], 110 to 148 mm Hg; no hypertensive crises; and normal central venous pressure) were given an isradipine infusion while the fetal heart rate was continuously recorded using a cardiotocograph. The infusion rate of isradipine was adjusted at regular intervals until control (DBP < 95 mm Hg) was achieved. The optimal dosage regimen in black patients was found to be an initial dose of 0.15 micrograms/kg/min, with increments of 0.0025 micrograms/kg/min every 15 min until control is achieved. Thereafter, a maintenance infusion of 0.15 micrograms/kg/min can be commenced. This dosage regimen is associated with neither maternal hypotension nor fetal heart rate deceleration. A second group of 10 patients (9 men and 1 woman) with DBP > 115 mm Hg (range, 117 to 135 mm Hg) and no features of hypertensive crises were also studied. The optimal dosage regimen in this patient group differed from the other in two respects: dosage increments could be made more rapidly (at 10-min intervals); and the dosage that produced blood pressure control needed to be continued for 30 min before the maintenance infusion was commenced. This regimen was not associated with hypotension.