Oral nifedipine versus intravenous labetalol in hypertensive urgencies and emergencies of pregnancy: a randomized clinical trial

Abstract

Background: Hypertensive crisis is an important cause of maternal and perinatal morbidity and mortality. Aim: To compare the efficacy of oral nifedipine and intravenous labetalol. Materials and methods: One hundred women with hypertensive crisis were randomized to receive either oral nifedipine 10 mg or intravenous labetalol 20 mg. Oral nifedipine was given 10 mg stat followed by 10 mg every 30 minutes up to a maximum of 50 mg. Intravenous labetalol was given 20 mg stat followed by 40 mg 30 minutes later then two more doses of 80 mg every 30 minutes up to a maximum of 220 mg. The primary outcome was the number of doses required to achieve target blood pressure (BP) and time required to reduce the mean arterial pressure by 25%. Secondary outcomes analysed included additional drugs required, resurgence of hypertensive crisis. Data were analysed using repeated measures analysis of variance (ANOVA), mixed ANOVA, unpaired t-test and chi square test and P value ≤0.05 was considered significant. Results: Systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MAP) were lower than baseline at all time points of follow-up in both nifedipine and labetalol groups ( P < 0.01). P < 0.05 by repeated measures ANOVA for overall trend of changes in SBP, DBP and MAP for within-group effects in both nifedipine and labetalol groups and P < 0.05 by mixed ANOVA for between-group effects during entire observation period. The magnitude of fall in SBP, DBP and MAP was greater in the labetalol group compared with the nifedipine group ( P < 0.05). Target BP was achieved in 90% in the nifedipine group and 92% in the labetalol group. Maternal and fetal adverse effects were infrequent. Conclusion: Both oral nifedipine and intravenous labetalol are effective in the treatment of hypertensive crisis. Intravenous labetalol may have benefits because it is more effective in reducing the SBP, DBP and MAP to target levels with a lower number of doses.