TABLE 1.

Medical therapy for prevention of postpartum hemorrhage

Medication	Mechanism of action	Route of administration and dose	Pharmacokinetics	Absolute and relative contraindications
Oxytocin	Stimulates oxytocin receptors in the uterus	IV: 10–40 units per 500–1000 mL, continuous infusion IM: 5–10 units; 4 dose maximum	Onset of action: 1–6 min (IV); 3–5 min (IM) Half-life: 4 min Peak plasma concentration: 30–60 min	Rare; SIADH, hypotension, hypersensitivity to drug.
Carbetocin	Stimulates oxytocin receptors in the uterus	IV: 100 μg/mL in 1 dose injected over 1 min	Onset of action of 1–6 min Half-life: 40 min Peak plasma concentration: 20–30 min	Hypersensitivity to drug, hypertension, cardiac disease.
Methylergonovine maleate (ergot alkaloid)	Serotoninergic agonist, dopaminergic weak antagonist, and α1-adrenergic partial agonist at receptors in the uterus	IM: 200 μg every 2–4 h; 5 doses maximum PO: 200 μg every 6–8 h for 2–7 d	Onset of action: 1–3 min Half-life: 30–120 min Peak plasma concentration: 40 min	Hypertension, preeclampsia, cardiovascular disease, hypersensitivity to drug.
Misoprostol	PGE1 agonist in the uterine myometrium	Sublingual, oral, or rectal (sublingual preferred): 600–1000 μg in 1-time dose; repeated doses not recommended	Onset of action: 8–11 min (PO, sublingual); 100 min (rectal) Half-life: 20–40 min Peak plasma concentration: 20–60 min	Rare; hypersensitivity to drug, concurrent anticoagulant therapy; efficacy is disputed.
Carboprost tromethamine (PGF2α)	PGF2α agonist in the uterine myometrium	IM or IMM: 250 μg every 15–90 min; 8 doses maximum	Onset of action: 5–10 min Half-life: 8 min Peak plasma concentration: 15–60 min	Asthma; relative contraindication for hypertension, cardiac disease, or active hepatic, pulmonary, or renal disease.
Tranexamic acid	Diminishes the dissolution of hemostatic fibrin by plasmin, stabilizing clots in uterine vessels	IV: 1 g (100 mg/mL) over a 10-min period Second dose may be administered if bleeding persists after 30 min or stops and restarts within 24 h after the first dose	Onset of action: within 5 min Half-life: 120 min Peak plasma concentration: 6–8 min	Hypersensitivity to drug, history of hypercoagulopathy, thromboembolic events during pregnancy.

IM, intramuscular; IMM, intramyometrial; IV, intravascular; PGE₁, prostaglandin E₁; PGF_2α, 15-methyl prostaglandin F_2α; PO, by mouth; SIADH, syndrome of inappropriate antidiuretic hormone secretion.