What is the recommended dosage of Primolut N (Norethisterone) for the management of dysmenorrhea?

Recommended Dosage of Primolut N (Norethisterone) for Dysmenorrhea

For dysmenorrhea management, the recommended dosage of Primolut N (norethisterone) is 5 mg daily, administered continuously for a minimum of 1 mg daily in continuous regimens, or 5 mg twice daily on days 19-26 of the menstrual cycle in sequential regimens. 1, 2

Dosing Regimens

Continuous Regimen

• Minimum effective dose of 1 mg oral norethisterone daily when used continuously 1
• Standard therapeutic dose of 5 mg daily is commonly prescribed for symptom management 2
• This regimen is particularly useful when withdrawal bleeding is not desired 1

Sequential/Cyclical Regimen

• 5 mg twice daily (10 mg total daily) administered on days 19-26 of the menstrual cycle 2
• This regimen allows for controlled withdrawal bleeding while still providing symptom relief 1

Mechanism of Action

• Norethisterone (progestin) helps reduce menstrual pain by:
  • Thinning the endometrial lining, resulting in decreased prostaglandin production 1
  • Reducing the volume of menstrual blood loss, which correlates with pain severity 2
  • Providing endometrial protection when used in appropriate doses 1

Efficacy for Dysmenorrhea

• Norethisterone has been shown to significantly reduce menstrual blood loss from a median of 109 mL to 92 mL after two cycles of treatment 2
• Progestins like norethisterone are effective alternatives to NSAIDs for dysmenorrhea management 3
• When used in continuous regimens, progestins may provide better symptom control than cyclical use 3

Considerations and Precautions

• Continuous regimens require a minimum of 1 mg of oral norethisterone daily for endometrial protection 1
• Progestins should not be used for more than 6 months continuously due to potential risk of meningioma 1
• Norethisterone may have a nonsignificant association with thromboembolism risk at higher doses 1
• Consider medroxyprogesterone acetate as an alternative in patients with high risk of venous embolism 1

Common Side Effects

• Irregular bleeding is the most common side effect, particularly during initial treatment cycles 3
• Other potential side effects include:
  • Headaches 3
  • Nausea 3
  • Changes in mood 1
  • Breast tenderness 1

Clinical Pearls

• Progestational agents like norethisterone are preferred over combined oral contraceptives for menstrual suppression during thrombocytopenic periods 1
• Continuous use regimens may provide better symptom control than cyclical regimens for dysmenorrhea 3
• If norethisterone is ineffective, consider alternative options such as NSAIDs or combined hormonal contraceptives 3, 4
• Adjust dosage based on individual response and tolerability 1