post-coital emergency contraception

see also gynaecology; contraception

• RANZCOG guideline emergency contraception (pdf)

• do pregnancy test if pregnancy possible although:
  • no evidence that it will adversely effect the fetus if given in early pregnancy or if it fails to prevent pregnancy
  • may not prevent pregnancy ⇒ advise to see a doctor at 4wks
• special precautions:
  • may increase INR in pts on warfarin
  • risk of STDs
• ongoing contraception

• in June 2002, levonorgestrel (LNE) became the 1st drug licensed for use as an emergency contraceptive in Australia.
• 1st dose 0.75mg LNE taken ASAP & repeat dose 12hrs later
• higher efficacy & lower side effect profile
• efficacy post coitus: within 24hrs = 95%; 25-48hrs = 85%; 49-72hrs = 58%;
• for pts presenting > 72hrs and less than 5 days post-coitus, consider emergency insertion of IUCD:
  • prevents > 99% of pregnancies
• relative C/I:
  • nulliparity
  • pts at high risk of acquiring STDs

• 2 doses of (100ug estradiol + 500ug levonorgestrel ie. 2 tablets per dose) taken 12hrs apart
• pack includes:
  • 2 tablets metoclopramide to be taken if feeling nauseous & in which case take one 30min prior to 2nd dose
  • 6 OCP tablets (2 extra in case emesis within 6hrs of 1st dose, premed with metoclopramide)
  • instruction sheet

• licenced in Australia in 2016
• can be used up to 120 hours (5 days) post-coital as a single 30mg dose and hence main use is for those presenting after 72hrs (those prior to 72hrs, LNG-EC should be considered instead)
• selective progesterone receptor modulator that works primarily by inhibiting ovulation
• more effective after 72hrs than LNG-EC and more effective in those weighing over 70kg
• re-administration after vomiting if vomiting is within 3hrs of dose
• tends to delay the menses (whereas LNG-EC tends to make it earlier)
• generally should NOT be used if either:
  • significant liver disease
  • asthmatics on corticosteroids
• other precautions
  • breastfeeding (do not use milk for at least 1 week)
  • absorption may be affected by gastric pH medications such as antacids, PPIs, antihistamines
  • efficacy may be reduced in patients taking enzyme inducers in prior 28 days
  • do not use with progesterone contraceptions (apart from Mirena IUCD) within 1 week of dose as efficacy of both may be reduced
  • do not use with LNG-EC in same menstrual cycle
  • unlike LNG-EC, evidence is not yet available to show no harm to a fetus - this do pregnancy test prior to administering

• a Cochrane review of studies in 2026¹⁾ appear to show mid-dose mifepristone (25-50 mg) prevented more pregnancies and were associated with fewer overall side effects (nausea and vomiting) than levonorgestrel but a higher likelihood of delayed menstruation and this could cause stress with patients thinking they may be pregnant - low dose (< 25mg) reduces the risk of early menses after treatment but slightly increases the risk of delayed menses compare to levonorgestrel but less risk than with mid-dose mifepristone
• not yet licensed in Australia for this purpose