Nifedipine or prazosin as a second agent to control early severe hypertension in pregnancy: a randomised controlled trial

Abstract

Objective: To determine whether nifedipine or prazosin is the more appropriate second-line antihypertensive agent in pregnancy.

Design: Randomised controlled trial.

Setting: Tygerberg Hospital, a tertiary referral centre.

Population: Women with early, severe pre-eclampsia or hypertension in pregnancy, whose blood pressure could not be adequately controlled by methyldopa 2 g/day, but were otherwise stable.

Methods: Nifedipine or prazosin were given and increased as necessary in a stepwise fashion. Once the maximum dose was reached, the other drug was added in a crossover pattern. Failure to control blood pressure, or the onset of maternal/fetal complications were indications for delivery. Patients reaching a minimum gestation of 34 weeks without complications were delivered electively.

Main outcome measures: Antenatal days gained; major maternal complications and perinatal survival.

Results: Days gained on the second antihypertensive agent did not differ significantly (P = 0.9), while more days were gained using nifedipine as the crossover 'third agent' (P = 0.01). In the nifedipine group better renal function was recorded, but more cases with isolated low platelet counts occurred. More cases of pulmonary oedema as well as more nonviable mid-trimester and third trimester intrauterine deaths occurred in the prazosin group.

Conclusion: Nifedipine and prazosin as second agents allowed comparable amounts of time to be gained, although this changed when used as crossover third-line agents. The efficacy and safety of nifedipine in this study are consistent with the results of other studies. A greater number of intrauterine deaths occurred in the prazosin group.