norethindrone acetate

norethindrone acetate

(nor eth in' drone)

Aygestin

Pregnancy Category X

Drug classes

Hormone

Progestin

Therapeutic actions

Progesterone derivative. Progesterone transforms proliferative endometrium into secretory endometrium; inhibits the secretion of pituitary gonadotropins, which prevents follicular maturation and ovulation; and inhibits spontaneous uterine contraction. Progestins have varying profiles of estrogenic, antiestrogenic, anabolic, and androgenic activity.

Indications

·        Treatment of amenorrhea; abnormal uterine bleeding due to hormonal imbalance

·        Treatment of endometriosis

·        Base: Component of some hormonal contraceptive preparations

Contraindications and cautions

·        Contraindicated with allergy to progestins; thrombophlebitis, thromboembolic disorders, cerebral hemorrhage or history of these conditions; hepatic disease, carcinoma of the breast or genital organs, undiagnosed vaginal bleeding, missed abortion; pregnancy; lactation.

·        Use cautiously with epilepsy, migraine, asthma, cardiac or renal dysfunction.

Available forms

Tablets—5 mg

Dosages

Administer orally only.

ADULTS

·        Amenorrhea; abnormal uterine bleeding: 2.5–10 mg PO starting with day 5 of the menstrual cycle and ending on day 25.

·        Endometriosis: 5 mg/day PO for 2 wk. Increase in increments of 2.5 mg/day every 2 wk until 15 mg/day is reached. May be maintained for 6–9 mo or until breakthrough bleeding demands temporary termination.

Pharmacokinetics

Route	Onset
Oral	Varies

Metabolism: Hepatic; T_1/2: Unknown

Distribution: Crosses placenta; enters breast milk

Excretion: Feces, urine

Adverse effects

·        CNS: Sudden, partial, or complete loss of vision; proptosis; diplopia; migraine; precipitation of acute intermittent porphyria; mental depression; pyrexia; insomnia; somnolence

·        CV: Thrombophlebitis, cerebrovascular disorders, retinal thrombosis, pulmonary embolism, thromboembolic and thrombotic disease, increased BP

·        Dermatologic: Rash with or without pruritus, acne, melasma or chloasma, alopecia, hirsutism, photosensitivity

·        GI: Cholestatic jaundice, nausea

·        GU: Breakthrough bleeding, spotting, change in menstrual flow, amenorrhea, changes in cervical erosion and cervical secretions, breast tenderness and secretion

·        Other: Decreased glucose tolerance, fluid retention, edema, increase in weight

Interactions

Drug-lab test

·        Inaccurate tests of hepatic and endocrine function

Nursing considerations

Assessment

·        History: Allergy to progestins; thrombophlebitis, thromboembolic disorders, cerebral hemorrhage; hepatic disease, carcinoma of the breast or genital organs, undiagnosed vaginal bleeding, missed abortion; pregnancy; lactation; epilepsy, migraine, asthma, cardiac or renal dysfunction

·        Physical: Skin color, lesions, turgor; hair; breasts; pelvic examination; orientation, affect; ophthalmologic examination; P, auscultation, peripheral perfusion, edema; R, adventitious sounds; liver evaluation; LFTs, renal function tests, glucose tolerance, Pap smear

Interventions

·        Arrange for pretreatment and periodic (at least annual) history and physical, including BP, breasts, abdomen, pelvic organs, and a Pap smear.

·        Warn patient prior to therapy to prevent pregnancy and to obtain frequent medical follow-up care.

·        WARNING: Use caution when administering drug to ensure preparation ordered is the one being used; norethindrone acetate is approximately twice as potent as norethindrone.

·        WARNING: Discontinue medication and consult physician if sudden partial or complete loss of vision occurs; if papilledema or retinal vascular lesions are present, discontinue drug.

·        WARNING: Discontinue medication and consult physician at sign of thromboembolic disease—leg pain, swelling, peripheral perfusion changes, shortness of breath.

Teaching points

·        Take drugs in accordance with a marked calendar.

·        Avoid pregnancy; serious fetal abnormalities or fetal death could occur.

·        You may experience these side effects: Sensitivity to light (avoid exposure to the sun; use sunscreen and protective clothing); dizziness, sleeplessness, depression (use caution driving or performing tasks that require alertness); skin rash, color changes, loss of hair; fever; nausea.

·        Report pain or swelling and warmth in the calves, acute chest pain or shortness of breath, sudden severe headache or vomiting, dizziness or fainting, numbness or tingling in the arm or leg.

Adverse effects in Italic are most common; those in Bold are life-threatening.