Second Line Therapy with Nifedipine in Severe Pregnancy Induced Hypertension

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Abstract
The calcium channel blocking agent, nifedipine, was assessed as second line therapy in 17 patients with severe hypertension in pregnancy. All patients were initially started on labetalol, the dose being increased to a maximum of 1200 mg/day. When this failed to control blood pressure, nifedipine was added in a dose of 10 mg q.d.s. increasing to 20 mg q.d.s. Median gestation at diagnosis was 32 weeks (range =16–36 weeks). Median duration of labetalol therapy was 6 days (range = 1 - 72 days) and median duration of nifedipine therapy was 11 days (range = 1 - 32 days). Median total duration of therapy prior to delivery was 14 days (range = 6 - 104 days). These patients all became resistant to labetalol therapy but following the addition of nifedipine satisfactory blood pressure control was obtained in all cases with a statistically significant fall in both systolic and diastolic blood pressure. No effect was noted on renal function. Delivery was carried out in 10 patients because they had reached an adequate gestation for delivery and in 6 patients for unsatisfactory blood pressure control. One patient had an intra-uterine death at 29 weeks gestation after 14 days therapy. Five infants were below the 10th centile for gestational age and 4 developed idiopathic respiratory distress syndrome. Minimal side effects were noted. These results suggest that nifedipine is a successful second line agent in the treatment of severe hypertension in pregnancy, and further controlled studies are now required to establish the precise role of nifedipine in the treatment of this disease.