Norethindrone Acetate

A to Z Drug Facts

 Actions Inhibits secretion of pituitary gonadotropins, thereby preventing follicular maturation and ovulation.

 Indications Treatment of secondary amenorrhea; endometriosis; abnormal uterine bleeding caused by hormonal imbalance in the absence of organic pathology (eg, uterine cancer).

 Contraindications Thrombophlebitis, thrombolic disorders, cerebral apoplexy, or a history of these conditions; markedly impaired liver function or liver disease; known or suspected carcinoma of the breast; undiagnosed vaginal bleeding; missed abortion; as a diagnostic test for pregnancy.

 Route/Dosage

Secondary Amenorrhea, Abnormal Uterine Bleeding

ADULTS: PO 2.5 to 10 mg/day for 5 to 10 days during second half of the theoretical menstrual cycle.

Endometriosis

ADULTS: PO 5 mg/day initially for 2 wk, then increase in increments of 2.5 mg/day q 2 wk until 15 mg/day is achieved. Therapy may be continued at this level for 6 to 9 mo or until breakthrough bleeding demands temporary termination.

 Interactions

Rifampin: Elimination of norethindrone may be increased, decreasing the therapeutic effect.

 Lab Test Interferences Pregnanediol determinations may be altered; thyroid and LFT results may be affected; increased amounts of coagulation factors; reduced response to metyrapone test.

 Adverse Reactions

CARDIOVASCULAR: Thrombophlebitis; cerebral thrombosis and embolism; hypertension; edema. CNS: Depression; changes in libido; changes in appetite; headache; nervousness; dizziness; fatigue. DERMATOLOGIC: Allergic rash; melasma; chloasma; hirsutism; alopecia; erythema multiforme; erythema nodosum; hemorrhagic eruption; itching. EENT: Neuro-ocular lesions (eg, retinal thrombosis, optic neuritis). GU: Breakthrough bleeding; spotting; amenorrhea; increased cervical erosion and secretion; cystitis. HEPATIC: Cholestatic jaundice. METABOLIC: Weight gain and loss. RESPIRATORY: Pulmonary embolism. OTHER: Premenstrual syndrome; backache.

 Precautions

Pregnancy: Category X. Lactation: Excreted in breast milk. Children: Safety and efficacy not established. Fluid retention: Use with careful observation when conditions that might be affected by fluid retention are present (eg, asthma, cardiac or renal dysfunction, epilepsy). Mental depression: Carefully observe patients with history of depression. Ophthalmic effects: Discontinue therapy if there are any sudden changes in vision or onset of proptosis, diplopia, migraine, papilledema, or retinal vascular lesions.

 Administration/Storage

• Administer prescribed dose once daily, without regard to meals. Administer with food if GI upset occurs.
• Store at controlled room temperature.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Review patient’s health history for any condition that would contraindicate norethindrone (eg, previous allergic reaction, known or suspected pregnancy, missed abortion, known or suspected cancer of the breast, undiagnosed vaginal bleeding, active or past history of thromboembolic disorders or stroke, liver dysfunction or disease).
• Ensure that breast and pelvic examination and Pap smear have been completed and documented before starting therapy.
• Monitor blood sugar in diabetic patient more frequently when drug is started or dose is changed. Report significant changes in blood sugar to health care provider.
• Monitor patient for CNS, RESP, CV, and general body side effects. Report to health care provider if noted and significant.
• Notify health care provider of the following symptoms: pain, swelling, redness or warmth in calves; sharp chest pain or sudden shortness of breath; sudden severe headache or migraine headache; visual disturbances; signs of liver dysfunction (eg, dark urine, jaundice); or signs of depression.

 Patient/Family Education

• Explain name, dose, action and potential side effects of drug.
• Instruct patient to take once daily as prescribed.
• Advise patient that medication can be taken without regard to meals, but to take with food if GI upset occurs.
• Warn women of childbearing potential of significant risks associated with taking this medication and becoming pregnant.
• Instruct diabetic patient to monitor blood glucose more frequently when drug is started or dose is changed and to inform health care provider of significant changes in readings.
• Instruct patient to report the following symptoms to health care provider: pain in groin or calves; sharp chest pain or sudden shortness of breath; abnormal vaginal bleeding; sudden severe headache or migraine headache; vision problems; yellowing of skin or eyes; or depression.
• Instruct women to notify health care provider if becoming pregnant, planning to become pregnant, or are breastfeeding.
• Instruct patient to not take any prescription or otc medications or dietary supplements unless advised to do so by the health care provider.
• Advise patient that follow-up visits and examinations may be required to monitor therapy and to be sure to keep appointments.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts