Makindo Medical Notes

BNF entry: Mifepristone – always check latest guidance. Mifepristone is an antiprogestogenic steroid. Used in medical abortion, cervical ripening, and induction of labour in intra-uterine fetal death.

⚙️ Mode of Action

• Blocks progesterone receptors → decidual breakdown, detachment of gestational sac.
• Sensitises the myometrium to prostaglandin-induced contractions.
• Ripens the cervix, aiding expulsion.

💊 Indications & Typical Doses (Adults)

⚠️ Always confirm doses in BNF or local protocols – regimens differ internationally.

• Cervical ripening before surgical termination (≤84 days): 200 mg PO once, 36–48 h before procedure.
• Medical termination ≤49 days: 200–600 mg PO once, then misoprostol 400 mcg PO or gemeprost 1 mg PV after 36–48 h. Observe ≥3 h.
• Medical termination 50–63 days: 200–600 mg PO once, then misoprostol or gemeprost as above. Follow-up within 2 wks.
• Termination 13–24 weeks: 200–600 mg PO once, followed 36–48 h later by repeated prostaglandin (gemeprost 1 mg PV q3h, max 5 mg; or misoprostol). If failure after 24 h → repeat prostaglandin course.
• Missed miscarriage: 200 mg PO once, then misoprostol 800 mcg PV/PO/SL after 48 h.
• Induction of labour in intra-uterine fetal death (no uterine scar): 200 mg PO once, followed by dinoprostone or misoprostol per national guidance.

⚠️ Contraindications

• Acute porphyrias.
• Chronic adrenal failure.
• Uncontrolled severe asthma.
• Suspected ectopic pregnancy (requires alternative treatment).
• Allergy to mifepristone or excipients.

⚠️ Cautions

• Haemorrhagic disorders or anticoagulant use (↑ bleeding risk).
• Uterine scarring (risk of rupture with prostaglandins).
• Cardiovascular disease, anaemia, or heavy smoking.
• Close supervision required for all regimens.

🔄 Interactions

• CYP3A4 inhibitors (e.g. ketoconazole, erythromycin) ↑ mifepristone levels.
• CYP3A4 inducers (e.g. rifampicin, carbamazepine, phenytoin) ↓ effectiveness.
• Avoid concomitant corticosteroids – antagonises glucocorticoid activity.

💥 Side Effects

• Abdominal cramps, pelvic pain.
• Heavy vaginal bleeding (sometimes severe).
• Nausea, vomiting, diarrhoea.
• Headache, dizziness, hot flushes.
• Infection (endometritis, PID).
• Rare: uterine rupture, toxic shock, severe skin reactions (TEN, erythema nodosum).

📚 References

• BNF: Mifepristone
• NICE Clinical Knowledge Summary: Termination of Pregnancy
• RCOG. Best practice in abortion care (2022)