From the Guidelines
Norethisterone can be prescribed to delay menstruation, but its use should be approached with caution due to potential cardiovascular and thrombotic risks, as highlighted in a 2021 study published in Blood Reviews 1. When considering norethisterone for menstruation delay, it is essential to weigh the benefits against the potential risks. The medication is typically prescribed at a dose of 5mg three times daily, starting 3-4 days before the expected period and continuing until the patient wants menstruation to begin. However, the choice of progestin should be based on the individual patient's risk profile, with natural micronized progesterone (MP) being a potentially safer alternative due to its more favorable pharmacological profile, as demonstrated in recent studies 1.
Some key points to consider when prescribing norethisterone include:
- Contraindications: current or history of thromboembolic disorders, breast cancer, severe liver disease, undiagnosed vaginal bleeding, pregnancy, porphyria, or hypersensitivity to the drug
- Cautious use: patients with cardiovascular risk factors, migraines, depression, or diabetes
- Efficacy: generally effective for most women when taken as directed, though breakthrough bleeding can occasionally occur
- Common side effects: nausea, headache, breast tenderness, and mood changes
- Mechanism of action: maintaining progesterone levels, preventing the uterine lining from shedding
It is crucial to take a thorough patient history before prescribing norethisterone to ensure safety, particularly regarding thromboembolic risk factors. The European Society for Human Reproduction and Embryology (ESHRE) recommends considering alternative progestogens, such as natural micronized progesterone, due to their safer pharmacological profiles 1. Ultimately, the decision to prescribe norethisterone should be made on a case-by-case basis, prioritizing the patient's individual risk profile and medical history.
From the Research
Indications for Norethisterone
- Norethisterone can be prescribed to delay menstruation, as it has been used as an oral contraceptive to postpone pregnancy 2.
- It is also used to treat heavy menstrual bleeding (HMB) or menorrhagia, with studies showing its effectiveness in reducing menstrual blood loss 3, 4.
- Norethisterone has been used in combination with estrogen for hormone replacement therapy in postmenopausal women, although the dose and delivery method may affect its efficacy 5.
Contraindications for Norethisterone
- Norethisterone is contraindicated in women with a history of thrombophlebitis, liver disease, or other conditions that may be exacerbated by progestogen therapy 2.
- It should not be used in women with known or suspected pregnancy, as it may affect fetal development 2.
- Norethisterone may not be suitable for women with a history of breast cancer or other hormone-sensitive cancers, as it may stimulate tumor growth 3.
Efficacy of Norethisterone
- Studies have shown that norethisterone is effective in reducing menstrual blood loss and improving quality of life in women with HMB 3, 4.
- The efficacy of norethisterone in delaying menstruation has been demonstrated in studies where it was used as an oral contraceptive 2.
- However, the dose and delivery method of norethisterone may affect its efficacy, with higher doses and longer treatment durations resulting in greater reductions in menstrual blood loss 6, 4.
- Norethisterone has been compared to other treatments for HMB, including tranexamic acid, danazol, and the progesterone-releasing intrauterine system (IUS), with varying results 3, 4.
Side Effects and Safety
- Common side effects of norethisterone include breast tenderness, intermenstrual bleeding, and nausea 3, 4.
- Norethisterone may also affect lipid profiles and liver function, although the clinical significance of these effects is unclear 6, 5.
- The safety of norethisterone has been evaluated in several studies, with no significant increases in adverse events reported 2, 4.