Nifedipine or hydralazine as a first-line agent to control hypertension in severe preeclampsia

Pre-eclampsia is one of the most serious and common complications of pregnancy. Nifedipine, a calcium channel blocker, and the vasodilator hydralazine have both been used as antihypertensive agents in this condition. The aim of this study was to determine which of these two agents is the most appropriate antihypertensive in the management of severe pre-eclampsia.

One hundred and twenty-six pre-eclamptic patients with a gestational age of more than 20 weeks were randomized to receive either 8 mg nifedipine sublingually or 5-10 mg intravenous hydralazine. Women with a history of heart failure and women receiving antihypertensive treatment during the course of the current pregnancy were excluded. For each patient the following data were recorded; the number of drug administrations, the time needed to control blood pressure, mean urinary output, the time interval between effective control and a new hypertensive crisis after each drug administration and relevant adverse effects in mother or fetus.

Effective control of blood pressure was achieved in both treatment arms. Data analysis indicated significantly fewer drug administrations in the nifedipine arm of the study. The time interval before a new hypertensive crisis following initial effective control of blood pressure was significantly longer in the nifedipine group when compared with hydralazine. Effective control of blood pressure was achieved more rapidly in multiparous patients receiving nifedipine (p=0.026). Mean urinary output before and after delivery was greater in the nifedipine arm of the study. There were no significant differences between the two groups in other variables. In addition, in neither group were there any serious adverse effects in mother or fetus.

Nifedipine is safe and more effective than hydralazine in controlling blood pressure in severe pre-eclampsia. It has the added advantage of being cheaper and more widely available than the latter and is easily administered.