A randomized trial of intravenous labetalol & oral nifedipine in severe pregnancy induced hypertension

Abstract

Background: Hypertension is the most frequently encountered medical disorder in obstetrics practice & remain a major cause of maternal, fetal & neonatal morbidity & mortality. The present study was undertaken to compare the time taken to reach the therapeutic goal blood pressure after using intravenous labetalol & oral nifedipine in severe pregnancy induced hypertension.

Methods: Randomly allocated patients received labetalol 20 mg initially, followed by escalating doses of 40, 80, 80 & 80 mg & a placebo tablet every 20 minutes or initially nifedipine tablet 10 mg orally with repeated doses of 20 mg every 20 minutes up to 5 doses & intravenous placebo 0.9% isotonic saline until the therapeutic goal blood pressure, Systolic ≤ 150 mmHg & diastolic ≤ 100 mmHg was achieved. Primary and secondary outcomes like the time interval required to achieve a blood pressure of ≤150/100 mmHg and urinary output, agent failure & adverse effects respectively were reported.

Results: Patients received oral nifedipine achieved the goal therapeutic blood pressure more rapidly in 28.2±11.7 minutes (mean±SD) as compared with 48.4±23.5 minutes in those received intravenous labetalol (p=0.001). The nifedipine group also required significantly fewer doses (3.5±0.5 vs 4.5±1.5; p=0.001) to reach the goal blood pressure. Urine output was significantly increased (p<0.001) at one hour after nifedipine therapy (95.6±1.2) compared with labetalol (41.9±1.6 ml) & remained significantly increased at 4,8,16&24 hours after initial therapy. Few adverse effects were reported but not significant. No patients required cross over therapy.

Conclusions: Oral nifedipine & intravenous labetalol regimens are effective in the management of severe hypertension in pregnancy; however nifedipine controls hypertension more rapidly & is associated with a significant increase in urinary output.