Postponing menstruation

This can be achieved by the use of norethisterone 5mg three times daily starting 3 days before the anticipated onset of menstruation. Menstruation will occur 2-3 days after stopping taking the norethisterone (NET).

Notes:

• a study by Kuhnz et al has demonstrated that NET is partly metabolised to ethinyl - estradiol (EE) which is why it is so effective at postponing menstruation. The equivalence is believed to be 1mg NET metabolises to 4 - 6mcgs EE (most combined oral contraceptives contain 20 - 30mcgs/day EE)
  
  
  • the relevance of this in practice is that NET is often used in women who are at risk of venous thromboembolism (VTE) and are unable to use combined hormonal contraception because of their risks (2)
    • in these women the clinician should transfer prescribing to Medroxyprogesterone acetate (Provera®) 10mgs bd or tds to delay their menstruation
      
      
  • use Medroxyprogesterone acetate 10mgs bd or tds instead of NET particularly in women who are overweight, smokers, aged over 35 or any other woman at risk of VTE (3)

A review suggests with respect to different oral progestogens to delay menses (4):

• Norethisterone
  • Norethisterone 5mg three times a day is licensed to delay periods. To be effective, norethisterone should be started at least 3 days before the expected period.
  • Norethisterone can be taken for up to 3 to 4 weeks if necessary. Periods usually resume within 3 days of discontinuing norethisterone.
  • The individual should be advised that norethisterone is not a contraceptive and so another form of contraceptive should be used to avoid pregnancy.
    
• Medroxyprogesterone
  • Medroxyprogesterone is an option if an individual has contraindications to oestrogens, such as migraines
  • Medroxyprogesterone tablets at a dose of 10mg three times a day have been used off-label to delay periods
    • dose has been shown to reduce heavy bleeding, although breakthrough bleeding can occur
  • Periods usually resume within 3 days of discontinuing medroxyprogesterone tablets.
  • The individual should be advised that oral medroxyprogesterone is not a contraceptive and so another form of contraceptive, such as condoms, should be used to avoid pregnancy.
  • Oral medroxyprogesterone may inhibit ovulation so fertility can be affected. The time taken for fertility to return to normal varies.

Reference:

• Kuhnz W, Heuner A, Humpel M. In vivo conversion of n orethisterone acetate to ethinylestradiol in postmenopausal women. Contraception. 1997;56:379
• Mansour D. Safer prescribing of therapeutic norethisterone for women at risk of venous thromboembolism. J Fam Plann Reprod Health Care 2012;38:148 - 9
• Primary Care Women's Health Forum (July 2013). e-update.
• NHS Specialist Pharmacy Service (May 2024). Choosing a medicine to delay periods