Last reviewed 2026-04-20 · How we verify

Micronor (norethisterone)

ORIAHNN combines elagolix, which suppresses LH and FSH to reduce ovarian sex hormones, with estradiol and norethindrone acetate to mitigate side effects.

Norethisterone (Micronor), marketed by Johnson & Johnson, is a hormonal contraceptive with a key patent expiring in 2028. Its primary indication is heavy menstrual bleeding associated with uterine leiomyomas, and it combines elagolix, estradiol, and norethindrone acetate to effectively manage symptoms while mitigating side effects. The primary risk is competition from off-patent generics such as megestrol acetate and medroxyprogesterone, which may erode market share.

At a glance

Mechanism of action

Elagolix, a GnRH receptor antagonist, binds to GnRH receptors in the pituitary gland, reducing the production of LH and FSH. This leads to lower levels of estradiol and progesterone, which helps reduce bleeding from uterine fibroids. Estradiol and norethindrone acetate are added to prevent bone loss and protect the uterus from unopposed estrogen effects.

Approved indications

• Heavy menstrual bleeding associated with uterine leiomyomas

Boxed warnings

• WARNING: THROMBOEMBOLIC DISORDERS AND VASCULAR EVENTS Estrogen and progestin combinations, including ORIAHNN, increase the risk of thrombotic or thromboembolic disorders including pulmonary embolism, deep vein thrombosis, stroke and myocardial infarction, especially in women at increased risk for these events [see Warnings and Precautions ( 5.1 )] . ORIAHNN is contraindicated in women with current or a history of thrombotic or thromboembolic disorders and in women at increased risk for these events, including women over 35 years of age who smoke and women with uncontrolled hypertension [see Contraindications ( 4 )] . WARNING: THROMBOEMBOLIC DISORDERS AND VASCULAR EVENTS See full prescribing information for complete boxed warning. Estrogen and progestin combinations, including ORIAHNN, increase the risk of thrombotic or thromboembolic disorders, especially in women at increased risk for these events. ( 5.1 ) ORIAHNN is contraindicated in women with current or a history of thrombotic or thromboembolic disorders and in women at increased risk for these events including women over 35 years of age who smoke or women with uncontrolled hypertension. ( 4 )

Common side effects

• hot flush
• headache
• fatigue
• metrorrhagia

Drug interactions

• digoxin
• midazolam
• rosuvastatin
• omeprazole
• rifampin
• strong CYP3A inhibitors
• OATP1B1 inhibitors

Key clinical trials

• Effects of VX-407 on the Pharmacokinetics of Oral Contraceptives in Healthy Participants (PHASE1)
• A Trial to Examine the Interaction of Repinatrabit With Ethinyl Estradiol/Norethindrone, Metformin,Carbamazepine, Rosuvastatin, and Methotrexate When Administered Together (PHASE1)
• Relative Desirability of Metformin vs. Birth Control Pill in Treating PCOS in Women of Later Reproductive Age (EARLY_PHASE1)
• Estradiol-mediated Inflammation and Central Sensitization in the Pathophysiology of Endometriosis-associated Pelvic Pain (PHASE3)
• Study of the Safety and Contraceptive Efficacy of Relugolix Combination Therapy in Women With Uterine Fibroids or Endometriosis Who Are at Risk for Pregnancy (PHASE3)
• Ovulation Incidence in Oral Contraceptive Users (PHASE3)
• A Randomized Feasibility Trial Comparing Drospirenone and Norethindrone for Postpartum Hypertension Management in Preeclampsia (PHASE4)
• Heavy Menstrual Bleeding Progestin Treatment in Bleeding Disorders Study

Primary sources

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Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Micronor CI brief — competitive landscape report
• Micronor updates RSS · CI watch RSS
• Johnson & Johnson portfolio CI