What are oxytocics (oxytocin-stimulating agents)?

From the Guidelines

Oxytocics are medications that stimulate uterine contractions, primarily used in obstetrics to induce or augment labor, prevent or treat postpartum hemorrhage, and manage other conditions requiring uterine contraction, with oxytocin, ergometrine, misoprostol, and carboprost being the most commonly used drugs 1.

Definition and Uses of Oxytocics

Oxytocics are used to stimulate uterine contractions, which are essential for labor induction, augmentation, and prevention or treatment of postpartum hemorrhage. The most commonly used oxytocic drugs include:

• Oxytocin (Pitocin)
• Ergometrine (Ergotrate)
• Misoprostol (Cytotec)
• Carboprost (Hemabate) These medications work by binding to specific receptors on uterine smooth muscle cells, increasing intracellular calcium, and enhancing myometrial contractility 1.

Administration and Dosage

For labor induction, oxytocin is typically administered intravenously at 1-2 mU/min, gradually increased every 30 minutes until adequate contractions occur (3-4 contractions per 10 minutes), with a maximum dose of 20-40 mU/min. For postpartum hemorrhage prevention, oxytocin 10 units IM or 5 units IV is given immediately after delivery, while treatment of established hemorrhage may require 10-40 units in 500-1000 mL of IV fluid. Misoprostol can be administered at 600-800 mcg sublingually, rectally, or orally for postpartum hemorrhage when oxytocin is unavailable 1.

Side Effects and Contraindications

Side effects of oxytocics include uterine hyperstimulation, water intoxication (with high-dose oxytocin), hypertension (with ergometrine), and gastrointestinal symptoms (with misoprostol). Contraindications include hypersensitivity, obstructed labor, placenta previa, and certain cardiovascular conditions, making careful patient selection essential for safe administration 1.

Key Considerations

It is essential to note that the injudicious use of uterotonics, such as oxytocin or misoprostol, to augment weak contractions during labor can lead to life-threatening complications, such as uterine rupture 1. Therefore, careful consideration and monitoring are necessary when using oxytocics to minimize the risk of adverse outcomes.

From the FDA Drug Label

Oxytocin injection (synthetic) acts on the smooth muscle of the uterus to stimulate contractions; response depends on the uterine threshold of excitability. It exerts a selective action on the smooth musculature of the uterus, particularly toward the end of pregnancy, during labor and immediately following delivery. Oxytocin stimulates rhythmic contractions of the uterus, increases the frequency of existing contractions and raises the tone of the uterine musculature.

Oxytocics (oxytocin-stimulating agents) are agents that stimulate uterine contractions.

• They act on the smooth muscle of the uterus to stimulate contractions.
• They exert a selective action on the smooth musculature of the uterus, particularly toward the end of pregnancy, during labor and immediately following delivery.
• Oxytocin is an example of an oxytocic agent, which stimulates rhythmic contractions of the uterus, increases the frequency of existing contractions and raises the tone of the uterine musculature 2.

From the Research

Definition and Use of Oxytocics

• Oxytocics, also known as oxytocin-stimulating agents, are used to initiate or augment uterine contractions during labor [(3,4)].
• Oxytocin is a peptide hormone that plays a key role in regulating the female reproductive system, including during labor and lactation 3.
• It is produced primarily in the hypothalamus and secreted by the posterior pituitary gland [(3,4)].

Types of Oxytocics

• Oxytocin is the most commonly used oxytocic agent [(3,4,5)].
• Misoprostol is another effective agent for cervical ripening and induction of labor 6.
• Other oxytocic agents may be used, but their safety and efficacy may vary 6.

Administration and Dosage

• Oxytocin can be administered as a medication to initiate or augment uterine contractions [(3,4)].
• The dosage of oxytocin varies, but it is typically administered at increasing rates from 1 to 3 mIU/min to a maximal rate of 36 mIU/min at 15- to 40-minute intervals 4.
• Misoprostol is typically administered in doses of 25-50 micrograms, inserted into the posterior vaginal fornix and repeated at 4-5-hour intervals if needed 6.

Safety and Efficacy

• Oxytocin is generally safe when administered correctly, but adverse perinatal outcomes can occur during uterine tachysystole 7.
• High-dose oxytocin regimens can shorten the length of labor and reduce the incidence of clinical chorioamnionitis 3.
• Misoprostol has a safety profile comparable to that of dinoprostone, but uterine hyperstimulation is a concern 6.
• The use of an oxytocin checklist can improve clinical outcomes, including decreases in tachysystole, cesarean births, and length of first stage labor 7.