Misoprostol (Cytotec©) Induction of labour

Section 2.1

Midwives may administer this drug after consulting with and on the order of a medical practitioner.

 Cytotec©, is a synthetic prostaglandin E1 analog and induces uterine contractions. Misoprostol is a water soluble tablet.

Indications and Clinical Use:

Misoprostol can be considered a safe and effective agent for labour induction with intact membranes and on an inpatient basis.

Contraindications:

Misoprostol should not be used if there is a history of previous cesarean section.

Warnings and Precautions:

Misoprostol should be used with caution in those with pre-existing cardiovascular disease. Oxytocin should be started no earlier than 4 hours after the last dose of misoprostol.

Pregnancy:

Contraindicated (oral)

Human Data Suggest Low Risk (Term Cervical Ripening)

Lactation:

Category L2 – Limited Data – Probably Compatible

Adverse Reactions:

Most common (especially with oral administration): GI – diarrhea (14 – 40%), abdominal pain (13 – 20%), pyrexia and shivering (11%). Pyrexia is more common when the dose exceeds 600 mcg. Greater incidence than 1%: nausea (3.2%), flatulence (2.9%), headache (2.4%), dyspepsia (2 %), vomiting (1.3%) and constipation (1.1%). Serious adverse events with the use of misoprostol are similar to those of other prostaglandins, and include uterine tachysystole with its potential fetal and maternal effects and meconium staining of liquor.

Dosage and Administration

  • Give 25 mcg orally with a drink of water (ensure that it is swallowed quickly to avoid sublingual absorption). Repeat every 2 hours as long as contractions are absent or non-painful or;
  • Give 25 mcg vaginally. Repeat every 6 hours as long as contractions are absent or non-painful. Oxytocin induction or augmentation can only be used 4 hours after the last dose.

Onset of Action:

Oral – 8 minutes
Sublingual – 11 minutes
Vaginal – 20 minutes
Rectal – 100 minutes

* Dose recommendation is variable; the lower dose has been chosen for safety purposes because of the increasing sensitivity of uterine receptors to misoprostol with increasing gestational age.

Half-life:

20 to 40 minutes.

If fetal heart assessment is atypical:

  • Follow FH Surveillance/Intrapartum Electronic Fetal Monitoring guidelines.
  • Consult with a physician to seek guidance regarding management plan.

If fetal heart assessment is abnormal:

  • Institute immediate intrauterine fetal resuscitation, prepare for expedited birth and immediately consult with a physician.

For tachysystole or hypertonus (six or more contractions in 10 minutes averaged over 30 minutes and/or the presence of mod/strong contraction(s) lasting more than 90 seconds and/or less than 30 seconds of adequate resting tone between contractions) and if fetal heart is abnormal:

  • Immediately consult with a physician.
  • A tocolytic such as nitroglycerin may be administered.

*Administration of nitroglycerin should be accomplished while simultaneously arranging an emergency consult with a physician.

(See section on Nitrates for administration)