levonorgestrel-only postcoital contraception

Last edited 03/2021 and last reviewed 11/2022

The mechanism of how levonorgestrel (LNG) act as an emergency contraception is not well understood. The mode of action is thought to be by inhibiting ovulation rather than inhibiting implantation (1)

• if taken before ovulation, LNG will inhibit ovulation for about 5-7 days by which time the sperm in the upper reproductive tract will loose its fertilising ability (1)

Previously the regimen involved taking two 750 mcg levonorgestrel tablets and repeating the dose 12 hours later; however since October 2003 giving 1.5 mg as a single dose has become the licensed norm in the UK (2)

• Levonelle 1500 (levonorgestrel 1.5 mg) became a prescription only medicine from the 1st of November 2005 (3)
• can be used at any time during the menstrual cycle but should not be administered if menstrual bleeding is overdue (4)

LNG should be taken as soon as possible preferably within 12 hours and no later than 72 hours of unprotected sexual intercourse (4)

Criteria for eligibility for levonorgestrel emergency contraception (5):

• Any individual presenting for emergency contraception (EC) between 0 and 96 hours following UPSI or when regular contraception has been compromised or used incorrectly. 
• No contraindications to the medication

Dose and frequency of administration (5)

• Levonorgestrel 1500mcg (1 tablet) to be taken as soon as possible up to 96 hours of UPSI.
• Dose for those individuals taking enzyme inducing medicines or herbal products: An individual who requests levonorgestrel whilst using enzyme-inducing drugs, or within 4 weeks of stopping them, can be advised to take a total of 3mg levonorgestrel (two 1500mcg tablets) as a single dose and within 96 hours of UPSI
• Dose for those individuals with a body mass index of more than 26kg/m2 or who weigh more than 70kg: An individual who requests levonorgestrel with a body mass index of more than 26kg/m2 or who weighs more than 70kg can be offered a total of 3mg levonorgestrel (two 1500mcg tablets) as a single dose and within 96 hours of UPSI

This Patient Group Direction (PGD) includes off-label use in the following conditions (5)

• Use between 72 and 96 hours post UPSI
• Increased dose for individuals with BMI over 26kg/m2 or weight over 70kg and in individuals using liver enzyme inducing agent
• Severe hepatic impairment
• Individuals with previous salpingitis or ectopic pregnancy
• Lapp-lactase deficiency
• Hereditary problems of galactose intolerance
• Glucose-galactose malabsorption

Adverse effects of levonorgestrel include:

• vomiting & nausea
  • vomiting is unusual (occurs in 1% of women), nausea is seen more frequently (in around 14%)
  • if the patient vomits within 2 hours of administration of LNG, a further dose should be taken as soon as possible
• disturbances in the cycle
  • FSRH advises that bleeding patterns may be temporarily disturbed and spotting may occur, but most individuals will have their next menstrual period within seven days of the expected time (5)
• abdominal pain
• fatigue
• dizziness
• breast tenderness
• ectopic pregnancies (1,6)

Reference:

• (1) Faculty of Family Planning and Reproductive Health Care Clinical Effectiveness Unit. FFPRHC Guidance (April 2006). Emergency contraception. J Fam Plann Reprod Health Care. 2006;32(2):121-8
• (2) Lancet (1998), 352, 428-33
• (3) Faculty of Sexual and Reproductive Healthcare (FSRH) 2006. Faculty statement from the CEU on Levonelle 1500 and the use of liver enzyme inducing drugs
• (4) ABPI Medicines Compendium 2009. Summary of product characteristics for Levonelle 1500 microgram tablet
• (5) Patient Group Direction (PGD) (NHS Specialist Pharmacy Service). Supply and/or administration of levonorgestrel 1500micrograms tablet(s) for emergency contraception (Accessed 17th March 2021).
• (6) Pulse 2004; 64 (24): 51