What is the name of the medication (prostaglandin analogue) used to dilate the cervix when inserted into the vagina?

Misoprostol for Cervical Ripening

The medication used to dilate the cervix when inserted into the vagina is misoprostol, a synthetic prostaglandin E1 analogue. 1, 2, 3, 4

Primary Medication

• Misoprostol is the most commonly used prostaglandin analogue for cervical ripening and dilation, available as vaginal or oral administration 1, 2, 3, 4
• The medication works by softening and dilating the cervix through prostaglandin-mediated cervical remodeling 5, 6

Alternative Prostaglandin Options

• Dinoprostone (prostaglandin E2) is another cervical ripening agent available as vaginal gel or vaginal insert (Cervidil®/Propess®) 7, 8, 6
• Dinoprostone vaginal insert contains 10 mg in a controlled-release device designed for sustained release over up to 24 hours 7, 8

Dosing Regimens

Misoprostol

• Vaginal administration: 25 mcg every 3-6 hours is the most effective route, with median time to vaginal delivery of 20.1 hours 4
• Oral administration: 20-25 mcg every 2-6 hours is the preferred non-vaginal route, resulting in fewer cesarean sections and lower uterine hyperstimulation rates 2, 3, 4

Dinoprostone

• Vaginal insert: 10 mg placed in posterior vaginal fornix for maximum 24 hours 7, 8
• Vaginal gel: Applied topically to cervix 6

Critical Safety Considerations

Absolute Contraindications for Misoprostol

• Previous cesarean delivery or uterine surgery: Misoprostol carries a 13% uterine rupture risk in women with prior cesarean, compared to 1.1% with oxytocin and 2% with prostaglandin E2 2, 4, 9
• The American College of Obstetricians and Gynecologists advises avoiding misoprostol entirely in women with previous cesarean delivery 3, 4

Monitoring Requirements

• Continuous fetal heart rate and uterine activity monitoring is mandatory from 30 minutes to 2 hours after each dose 3, 4
• Trained obstetrical personnel in hospital setting required 9

Comparative Effectiveness

• Misoprostol vs. placebo: Reduces need for mechanical dilation from 80% to 14-39%, with fewer intraoperative complications (OR 0.37) 5
• Misoprostol vs. dinoprostone: More effective cervical dilation (OR 0.58) and fewer complications (OR 0.32), though more side effects 5
• Misoprostol vs. laminaria (osmotic dilator): Laminaria more effective, with fewer women requiring mechanical dilation (OR 5.96 favoring laminaria) 5

Common Side Effects

• Mild abdominal pain and cramping 1, 5
• Vaginal bleeding 1, 5
• Increased body temperature 5
• Preoperative pain more common than with placebo 5

Clinical Context Applications

For IUD Placement

• Misoprostol not routinely recommended for IUD placement pain reduction 1
• Consider only for failed previous placement: 200 mcg vaginal misoprostol at 10 and 4 hours prior, or 400 mcg vaginal 4 hours prior in nulliparous patients 1

For Labor Induction

• Oral misoprostol solution 20-25 µg every 2-6 hours is preferred pharmacological method for unfavorable cervix 2, 3
• Mean time from contractions to delivery approximately 7.5 hours 10
• Vaginal birth occurs in 85% of cases 10

Special Population Considerations

• Advanced liver failure: Misoprostol may be less suitable as it requires hepatic metabolism to convert from E1 to active E2 prostaglandin 2, 3
• Cardiac patients or cyanosis: Mechanical methods (Foley catheter) preferred over prostaglandins to avoid systemic vascular resistance drops 2
• Active cardiovascular disease: Dinoprostone contraindicated due to profound blood pressure effects 2