Medication*DosageMaternal adverse effectsFetal or newborn adverse effectsContraindications
Nifedipine (calcium channel blockers)21,42 30-mg loading dose orally, then 10 to 20 mg every 4 to 6 hours (maximal dosage: 180 mg per day)Dizziness, flushing, and hypotension; suppression of heart rate, contractility, and left ventricular systolic pressure when used with magnesium sulfate; elevation of hepatic transaminase levelsNo known adverse effectsHypotension and preload-dependent cardiac lesions, such as aortic insufficiency
Indomethacin (prostaglandin inhibitor, nonsteroidal anti-inflammatory drug)21,41,42 50- to 100-mg loading dose orally or rectally, then 25 to 50 mg orally every 4 to 6 hours; therapy is not recommended for greater than 48 hours because of potential change in amniotic fluid levels and premature closing of fetal ductus arteriosusNausea, esophageal reflux, gastritis, emesis; platelet dysfunction is rarely of clinical significance in patients without an underlying bleeding disorderIn utero constriction of ductus arteriosus, oligohydramnios, necrotizing enterocolitis in preterm newborns, patent ductus arteriosus in infantsPlatelet dysfunction or bleeding disorder, hepatic dysfunction, gastrointestinal ulcerative disease, renal dysfunction, asthma (in women with hypersensitivity to aspirin)
Terbutaline (beta-adrenergic receptor agonist)21,42

  • 0.25 mg subcutaneously every 20 to 30 minutes for up to four doses or until tocolysis is achieved, then 0.25 mg every 3 to 4 hours until the uterus is quiet for 24 hours

  • Alternate dosage: 2.5 to 5 mcg per minute via intravenous infusion, increasing by 2.5 to 5 mcg per minute every 20 to 30 minutes to a maximum of 25 mcg per minute or until the contractions have abated; at this point, the infusion is reduced by decrements of 2.5 to 5 mcg per minute to the lowest dose that maintains uterine quiescence

  • Therapy should not be continued longer than 48 to 72 hours because of serious adverse effects

Tachycardia, hypotension, tremor, palpitations, shortness of breath, chest discomfort, pulmonary edema, hypokalemia, and hyperglycemiaFetal tachycardiaTachycardia-sensitive cardiac disease and poorly controlled diabetes mellitus
Magnesium sulfate 21,42 6-g bolus intravenously over 20 minutes, then 2 g per hour as continuous infusionFlushing, diaphoresis, nausea, loss of deep tendon reflexes, respiratory depression, and cardiac arrest; suppression of heart rate, contractility, and left ventricular systolic pressure; produces neuromuscular blockade when used with calcium channel blockersNeonatal depressionMyasthenia gravis