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

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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.