Overview
Norethisterone (norethindrone) is a synthetic progestin used primarily for gynecological conditions. It works by mimicking progesterone to regulate the menstrual cycle and manage conditions like abnormal uterine bleeding and endometriosis. It is commonly prescribed for hormonal regulation and contraception.
Mechanism of Action
Norethisterone is a synthetic progestin that binds to progesterone receptors, exerting progestogenic effects. It inhibits gonadotropin secretion from the pituitary gland, suppresses ovulation, and transforms proliferative endometrium into secretory endometrium, thereby regulating menstrual cycles and managing conditions like abnormal uterine bleeding.
Indications
- Management of heavy menstrual bleeding associated with uterine leiomyomas (fibroids) in premenopausal women
- Treatment of abnormal uterine bleeding
- Endometriosis management
- Hormonal contraception
- Secondary amenorrhea
Common Doses
- 5 mg
- 10 mg
- 15 mg
Dosage
Typical dosage varies by indication but commonly ranges from 5-15 mg daily in divided doses for menstrual disorders. For contraception, it is often used as part of combination regimens. Treatment duration should be individualized based on clinical response.
Contraindications
- High risk of arterial, venous thrombotic, or thromboembolic disorders
- Current or history of deep vein thrombosis or pulmonary embolism
- Vascular disease (cerebrovascular disease, coronary artery disease, peripheral vascular disease)
- Thrombogenic valvular or rhythm diseases of the heart
- Inherited or acquired hypercoagulopathies
- Uncontrolled hypertension
- Migraine headaches with aura in women over age 35
- Pregnancy
- Known osteoporosis
- Current or history of breast cancer or other hormonally-sensitive malignancies
- Known hepatic impairment or disease
- Undiagnosed abnormal uterine bleeding
- Known anaphylactic reaction or hypersensitivity to norethisterone
- Concomitant use with strong OATP1B1 inhibitors
Side Effects
- Thromboembolic disorders
- Bone loss
- Suicidal ideation and behavior
- Hepatic transaminase elevations
- Elevated blood pressure
- Changes in carbohydrate and lipid metabolism
- Alopecia
- Nausea
- Headache
- Breast tenderness
- Weight changes
- Mood changes
- Irregular bleeding
Interactions
- Inhibitors of organic anion transporting polypeptide (OATP)1B1 that increase elagolix plasma concentrations
- Enzyme inducers (e.g., rifampin, carbamazepine) may reduce efficacy
- Anticoagulants (potential altered coagulation parameters)
- Antidiabetic drugs (may affect glucose control)
- Other hormonal therapies
Counseling Points
- Take medication exactly as prescribed, typically with food to reduce gastrointestinal upset
- Report any signs of blood clots (e.g., leg pain, chest pain, shortness of breath)
- Monitor for mood changes or depressive symptoms
- Use non-hormonal contraception if prescribed for non-contraceptive indications
- Regular bone density monitoring may be needed with long-term use
- Report unusual vaginal bleeding or severe headaches
- Inform healthcare provider of all medications being taken