Thomas Easterling et al. conducted an open-label, randomized controlled trial to assess the efficacy and safety of three oral antihypertensives in treating severe hypertension in pregnancy in a low-resource setting and their findings may change your practice for the greater good. The trial used nifedipine retard, labetalol, and methyldopa. They are the most widely used antihypertensives during pregnancy.
Thomas Easterling et al. enrolled 894 women after they met the inclusion criteria. The criteria were, age above 18 years, at least 28 weeks of gestation, severe hypertension at the time of enrollment – defined as a systolic BP ≥160 mm Hg or diastolic BP ≥110 mm Hg, and ability to swallow oral medications).
In a ratio of 1:1:1, the women received either 10mg nifedipine, 200mg labetalol, or 1000mg methyldopa. They were all oral formulations.
For nifedipine, labetalol, women received similar doses every hour if blood pressures were still high.
For methyldopa, it was only a single dose with no escalation. If blood pressures were still high, women received nifedipine after an hour. The primary outcome was blood pressure controlled at systolic BP 120 – 150 mm Hg or diastolic BP 70 – 100 mm Hg within 6 hours without adverse effects.
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The study showed that nifedipine often achieved the primary outcome by significant numbers than methyldopa. For nifedipine and labetalol groups or labetalol and methyldopa groups, there were no significant differences. One woman in the labetalol group had a seizure during labour. There were six stillbirths, one from the nifedipine group, two from the group of labetalol, and three from the methyldopa group. There no maternal death and no birth experienced more than one adverse event.
The study demonstrated that all three oral antihypertensives reduced blood pressure to meet the reference range in most women. Throughout the study nifedipine more frequently reduced the blood pressure than either labetalol or methyldopa. We consider these drugs to be viable options for treating severe hypertension in low-resource settings.
Gaining further insight into this study is necessary, but first, let’s get a few facts about hypertension in pregnancy straight.
The most common medical disorder in pregnancy is hypertension, affecting 10% of pregnancies. To reduce the risk of maternal complications, we recommend that clinicians reduce severely elevated blood pressures during pregnancy. WHO urges that clinicians should treat severe hypertension in pregnancy using intravenous hydralazine or methyldopa. However, we note that intravenous hydralazine is not widely available in many low- and middle-income countries. In areas where such a drug is available, such health-care providers are often too busy to use it since it both requires intravenous access and careful fetal monitoring.
It is where this study comes in handy. It is the first of its kind to assess three oral regimens in the management of severe hypertension in pregnancy – the results are promising. There was an added relative effectiveness of methyldopa, a drug that is widely available in many clinical settings.
The study provides some vital reassurance for the use of drugs available in all clinical settings, given the fact that oral antihypertensives are widely available in low- and middle-income countries. The study also demonstrated a rationale for a structured approach to the use of oral antihypertensives in a range of clinical scenarios, in the sense that clinicians reduce treatment delays.
WHO should broaden the essential drugs list options for the management of severe hypertension. The health icon only lists methyldopa and intravenous hydralazine. Nifedipine is currently only available for the treatment of preterm birth. We should add it, as well as oral labetalol.