Oral Nifedipine more effective than methyldopa for lowering high BP in pregnancy within 6 hours

Oral Nifedipine more effective than methyldopa for lowering high BP in pregnancy within 6 hours, finds a Lancet study.

Pregnancy-induced hypertension or high blood (BP) pressure is one of the major threats to both the mother and the child. Three WHO recommended antihypertensives, nifedipine retard, labetalol, and methyldopa are used to treat severely high BP during pregnancy.

The study revealed that all three antihypertensive drugs were efficient in reducing blood pressure in a high proportion of women and maternal adverse events. Oral nifedipine retard was significantly more effective for lowering blood pressure within 6 hours than oral methyldopa. However, intensive care unit admissions were significantly more frequent in the nifedipine group. The study appeared in the Journal Lancet.

High blood pressure during pregnancy is common, affecting 1 in 10 pregnancies. Control of blood pressure is highly recommended to reduce the risk of complications during pregnancy. Severe hypertension in pregnancy is defined by a systolic blood pressure of at least 160 mm Hg or diastolic blood pressure of at least 110 mm Hg, and either of these clinical signs is considered to be an obstetric emergency for both mother and fetus; urgent antihypertensive treatment is recommended.

The researchers conducted a multicentre, parallel-group, open-label, randomized controlled trial, compared three WHO-recommended oral antihypertensives, labetalol, nifedipine retard, and methyldopa for the management of severe hypertension in pregnancy in low-resource settings.

They compared the three oral antihypertensives in two public hospitals in Nagpur, India. Pregnant women were eligible for the trial if they were aged at least 18 years; they were pregnant with fetuses that had reached a gestational age of at least 28 weeks; they required pharmacological blood pressure control for severe hypertension (systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥110 mm Hg); and were able to swallow oral medications.

Women were randomly assigned to receive 10 mg oral nifedipine, 200 mg oral labetalol (hourly, in both of which the dose could be escalated if hypertension was maintained), or 1000 mg methyldopa (a single dose, without dose escalation). Masking of participants, study investigators, and care providers to group allocation were not possible because of different escalation protocols in the study groups. The primary outcome was blood pressure control (defined as 120–150 mm Hg systolic blood pressure and 70–100 mm Hg diastolic blood pressure) within 6 h with no adverse outcomes.

Key findings of the study

• Between April 1, 2015, and Aug 21, 2017, we screened 2307 women for their inclusion in the study.


• We excluded 61% of women who were ineligible, declined to participate, had impending eclampsia, were in active
  labor, or had a combination of these factors.


• 4%women in the nifedipine group, 3% women in the labetalol group, and 4% women in the methyldopa group were ineligible for treatment (because they had only one qualifying blood pressure measurement) or had treatment stopped (because of delivery or transfer elsewhere).


• 39% of women were randomly assigned to a treatment group and were included in the intention-to-treat analysis: 33% of women were assigned to receive nifedipine,


• 33% of women were assigned to receive labetalol, and 33% of women were assigned to receive methyldopa.


• The primary outcome was significantly more common in women in the nifedipine group than in those in the methyldopa group.


• However, the primary outcome did not differ between the nifedipine and labetalol groups or the labetalol and methyldopa groups.


• Seven serious adverse events were reported during the study: one woman in the labetalol group had an intrapartum seizure and six neonates (one [<1%] neonate in the nifedipine group, two [1%] neonates in the labetalol group, and
  three [1%] neonates in the methyldopa group) were stillborn.


• No birth had more than one adverse event.

"All oral antihypertensives reduced blood pressure to the reference range in most women. As single drugs, nifedipine retard use resulted in a greater frequency of primary outcome attainment than labetalol or methyldopa use. All three oral drugs—methyldopa, nifedipine, and labetalol—are viable initial options for treating severe hypertension in low-resource settings." concluded the authors.

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DOI:https://doi.org/10.1016/S0140-6736(19)31282-6