A Comparative Study of Intravenous Isradipine and Dihydralazine in the Treatment of Severe Hypertension of Pregnancy in Black Patients

Abstract

Objective: To compare the efficacy and safety of intravenous isradipine with dihydralazine in severe hypertension of pregnancy in Black patients.

Methods: In this randomized study 40 Black patients with severe hypertension of pregnancy (DBP ≥ 110 mm Hg) at a tertiary referral hospital received intravenous isradipine [an initial dose of 0.15μ,g kg^-1 min^-1 for 15 min with increments of 0.0025 ixg kg^-1 min^-1 every 15 min until diastolic blood pressure (DBP) control (DBP < 95 mm Hg) was achieved, followed by a maintenance infusion of 0.15 μg kg^-1 min^-1 which was given for 15 min] or dihydralazine (6.25 mg given intravenously over 10 min; the dosage was repeated after 20 min if control was not achieved).

Mean Outcome Measures: DBP < 95 mm Hg; fetal heart rate deceleration; fetal outcome.

Results: Mean systolic blood pressure was reduced from 190.9 (95% CI 182.7-199.0) mm Hg to 137.6 (131.9-143.3) mm Hg in the isradipine group and from 187.9 (180.0-195.7) to 142.4 (133.0-151.7) mm Hg in the dihydralazine group. The corresponding values for DBP were 125.8 (121.9-129.6) to 87.9 (85.0-90.7) and 124.7 (120.6-128.8) to 89.3 (85.3-93.3) mm Hg, respectively. Differences between the groups with respect to entry and minimum blood pressure were not statistically significant. Blood pressure control was achieved in 19 patients who received isradipine. In the dihydralazine group, 15 of the patients required the second dose of dihydralazine; control was achieved in 16 patients, 5 after receiving 6.25 mg dihydralazine. Maternal heart rate rose from 83.5 (78.5-88.4) to 118.7 (108.5-128.9) beats min“¹ following isradipine and from 78.6 (72.9-84.3) to 106.1 (98.7-113.5) beats min”¹ following dihydralazine. Hypotension did not occur in any patient. Fetal heart rate deceleration was noted in 2 patients receiving isradipine and in 5 patients receiving dihydralazine. Fetal outcome was similar in the two groups.

Conclusions: These preliminary data indicate that the efficacy and safety of intravenous isradipine is comparable to that of dihydralazine, and that isradipine could be a useful agent in lowering very high blood pressure levels rapidly in patients with severe hypertension of pregnancy.

Key Words:

• Isradipine
• Severe hypertension of pregnancy