BACKGROUND AND PURPOSE:

• Zulfeen et al. (European Journal of Obstetrics & Gynecology and Reproductive Biology, 2019) assessed the efficacy of IV labetalol compared to oral nifedipine for the treatment of severe hypertension in pregnancy

METHODS:

• Parallel assignment double-blind randomized controlled trial (RCT)
• Participants
  • Pregnant women >28 weeks gestation
  • Admitted with severe hypertension
    • Systolic BP of ≥160 mmHg and/or diastolic BP of ≥110 mmHg
    • On two separate occasions
    • 30 min apart in lateral recumbent position
• Exposures
  • Labetalol group: 20 mg labetalol initially followed by escalating doses of 40 mg, 80 mg, 80 mg and 80 mg (5 doses) every 15 min to a maximum of 300 mg
  • Nifedipine group: 10 mg nifedipine initially followed by repeated doses of 20 mg every 15 min (total 5 doses) to a maximum of 90 mg
• Primary outcome
  • Mean time take to achieve target BP of systolic 150 and /or diastolic 100 mmHg
• Secondary outcomes
  • Number of doses required | Adverse effects | Maternal and perinatal outcome

RESULTS:

• 120 women were included
  • 60 randomized to each group
• No patients in the nifedipine group required labetalol | 3 patients in the labetalol group required nifedipine after maximum dose of labetalol
• The average time to achieve the target BP was higher in the labetalol group
  • Labetalol: 36.75 min
  • Nifedipine: 27.25 min
  • mean difference 9.5 min (p=0.002)
• Nifedipine was more likely to achieve target blood pressure
  • Hazard Ratio (HR) 1.8 (95% CI, 1.23 to 2.67)
• The nifedipine group required significantly lower mean number of doses (p=0.002)
  • Labetalol: 2.45 doses
  • Nifedipine: 1.82 doses
• Perinatal outcomes
  • Few adverse drug effects: Hypotension in nifedipine group (1) was transient and asymptomatic
  • No significant differences in maternal/fetal complications (however, small ‘n’)
• Mean urine output (mL/hour) was higher in nifedipine group (66.82) vs labetalol group (55.08); p=0.001)

CONCLUSION:

• Both labetalol and nifedipine effectively reduced blood pressure, though nifedipine had the following benefits
  • Lowered blood pressure more quickly
  • Was 1.8 times more likely to achieve target blood pressure
  • Maintained higher urine output
• Authors suggest that

Oral nifedipine may be a better alternative due to its ease of oral administration and a flat dosing regimen.

Learn More – Primary Sources:

IV labetalol and oral nifedipine in acute control of severe hypertension in pregnancy–A randomized controlled trial

Related ObG Topics:

ACOG Guidance: Emergency Treatment for Severe Hypertension in Pregnancy

Labetalol or Nifedipine for Chronic Hypertension in Pregnancy?

Diagnosing Preeclampsia – Key Definitions and ACOG Guidelines

ACOG Preeclampsia Guidelines: Antenatal Management and Timing of Delivery