Oral nifedipine(Drug information on nifedipine) and intravenous labetalol(Drug information on labetalol) show similar efficacy in their ability to control hypertensive emergencies of pregnancy, according to new research published in BJOG: An International Journal of Obstetrics & Gynaecology.
Researchers from the department of obstetrics and gynecology in the Faculty of Medicine at the University of Malaya, Kuala Lumpur, Malaysia, conducted a double-blind randomized trial of pregnant women (N=50) with severe gestational hypertension (defined as at least 160/110 mmHg) who required immediate treatment. The pregnant women were randomized to one of the following treatment arms: nifedipine (10 mg tablet, orally, up to five doses) along with an intravenous placebo saline injection or intravenous labetalol injection (in an escalating dose regimen of 20 mg, 40 mg, 80 mg, 80 mg, and 80 mg) and a placebo tablet every 15 minutes until the target blood pressure was achieved. (Target blood pressure was defined as 150/100 mmHg or lower.) If the initial treatment was not effective, the patient was crossed over to the alternative treatment regimen. The researchers used time to obtain target blood pressure as the main outcome measure when comparing the treatments.
The researchers found that the median time to achieve target blood pressure was slightly higher for the patients receiving labetalol as compared to those who received nifedipine. Specifically, the median time to achieve target blood pressure was 45 minutes for labetalol versus 30 minutes for nifedipine. Based on repeated measures analysis of variance, the researchers noted that both systolic and diastolic blood pressure significantly decreased in the first hour, but they did not find any difference between the treatment groups for both systolic and diastolic blood pressure trends over time. The study authors further noted that 20% of the patients required crossover treatment. The researchers did not find any significant hypotension or changes in fetal heart rate as a result of either medication.
Overall, the researchers concluded, “Oral nifedipine and intravenous labetalol regimens are similarly effective in the acute control of severe hypertension in pregnancy.”
“This study provides useful supporting information on the choice and effectiveness of antihypertensive drugs for control of an acute hypertensive crisis experienced by a woman with severe preeclampsia,” Dr Michael Paech, professor in the division of anesthesiology at the University of Western Australia, shared in an online commentary. “The study confirms current practice in that two popular drugs, oral nifedipine and intravenous labetalol, did not differ in efficacy and were successful in reducing systolic and diastolic pressure within 1 hour in most women.”