Table 3. Drugs for Urgent Control of Severe Hypertension in Pregnancy

Drug (FDA Risk*)Dose and RouteConcerns or Comments
Drugs indicated for acute elevation of diastolic BP≥105 mm Hg; the goal is gradual reduction to 90 to 100 mm Hg. NHBPEP indicates National High Blood Pressure Education Program Working Group Report on High Blood Pressure in Pregnancy; FDA, Food and Drug Administration.
*Food and Drug Administration classification, C indicates that either studies in animals have revealed adverse effects on the fetus (teratogenic, embryocidal, or other) and/or there are no controlled studies in women or studies in women and animals are not available. Drugs should only be given if the potential benefits justify the potential risk to the fetus.
†Adverse effects for all of the agents, except as noted, may include headache flushing, nausea, and tachycardia (primarily because of precipitous hypotension and reflex sympathetic activation).
‡We would classify in category D: there is positive evidence of human fetal risk, but the benefits of the use in pregnant women may be acceptable despite the risk (eg, if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs can not be used or are ineffective).
Labetalol (C)10 to 20 mg IV, then 20 to 80 mg every 20 to 30 minutes, maximum of 300 mg; for infusion: 1 to 2 mg/minBecause of a lower incidence of maternal hypotension and other adverse effects, its use now supplants that of hydralazine; avoid in women with asthma or congestive heart failure
Hydralazine (C)5 mg, IV or IM, then 5 to 10 mg every 20 to 40 minutes; once BP controlled repeat every 3 hours; for infusion: 0.5 to 10.0 mg/h; if no success with 20 mg IV or 30 mg IM, consider another drugA drug of choice according to NHBEP; long experience of safety and efficacy
Nifedipine (C)Tablets recommended only: 10 to 30 mg PO, repeat in 45 minutes if neededWe prefer long-acting preparations; although obstetric experience with short acting has been favorable, it is not approved by the FDA for management of hypertension
Diazoxide (C)30 to 50 mg IV every 5 to 15 minutesUse is waning; may arrest labor; causes hyperglycemia
Relatively contraindicated nitroprusside (C)Constant infusion of 0.25 to 5.00 μg/kg per minutePossible cyanide toxicity if used for >4 hours; agent of last resort