Uterotonic agents: Symptoms

Uterotonic agents increase the frequency and tonicity of uterine contractions. They are used to induce labor and to treat postpartum hemorrhage and uterine atony. Their side effects are related to their mechanism of action.

Oxytocin analogues:

Oxyctocin is the endogenous posterior pituitary hormone that stimulates cervical dilation and uterine contractions during labor. Its synthetic, IV analogue, Pitocin, is often used to induce labor through IV titration. Side effects include hypotension at high doses due to systemic vascular smooth muscle relaxation and subsequent reflex tachycardia.

Ergot alkaloids:

Ergot alkaloids are part of a family of chemicals originally derived from fungi. Methylergonovine (Methergine) causes intense uterine contraction and is used postpartum for atony and/or PPH. It causes non-specific smooth muscle contraction and therefore its side effects are hypertension, coronary vasospasm, and bronchospasm. Usually given in a single IM dose (to avoid severe and profound hypertension if given as an IV bolus) but can also be used as a diluted IV infusion. Methylergonovine is contraindicated in hypertensive patients.

Prostaglandins:

Carboprost (Hemabate) is a synthetically derived analogue of Prostaglandin F₂ that causes uterine contractions and used to treat uterine atony and PPH. Side effects include increased cardiac output, increased pulmonary vascular resistance, bronchospasm and nausea. Carboprost is contraindicated in patients with asthma. The Prostaglandin E₁ analogue, misoprostol (Cytotec) and Prostaglandin E₂ (Dinoprostone) may cause nausea, hypotension and fever. These latter two do not have the bronchospasm associated with carboprost. Prostaglandins are administered via intramuscular injection.