Megestrol Acetate

A to Z Drug Facts

Actions Inhibits secretion of pituitary gonadotropins, thereby preventing follicular maturation and ovulation (contraceptive effect); inhibits spontaneous uterine contraction; transforms proliferative endometrium into secretory endometrium.

 Indications Palliative treatment of advanced inoperable, recurrent, or metastatic carcinoma of breast or endometrium.

Appetite stimulation in HIV-related cachexia.

 Contraindications Hypersensitivity to progestins; as diagnostic test for pregnancy.

 Route/Dosage

Breast Cancer

ADULTS: PO 40 mg qid.

Endometrial Cancer

ADULTS: PO 40 to 320 mg/day in divided doses.

Interactions None well documented.

Lab Test Interferences Endocrine, coagulation (increased amounts of coagulation factors), thyroid and LFT results may be affected by progestins; may alter metyrapone test results; may decrease glucose tolerance.

 Adverse Reactions

CARDIOVASCULAR: Hypertension; thromboembolic phenomena, including thrombophlebitis and pulmonary embolism. CNS: Insomnia; fatigue. DERMATOLOGIC: Rash; alopecia; mild acne. GI: Abdominal pain or discomfort; nausea; vomiting. GU: Breakthrough bleeding; change in menstrual flow; changes in cervical erosion and secretions; impotence. HEPATIC: Cholestatic jaundice. RESPIRATORY: Dyspnea. OTHER: Breast tenderness; masculinization of female fetus; edema; weight changes; decreased libido; tumor flare; carpal tunnel syndrome; increased appetite.

 Precautions

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

 Administration/Storage

• Store in dry, cool place at room temperature.

 Assessment/Interventions

• Obtain complete patient history, including drug history and any known allergies. Note history of thromboembolic disease.
• Assess results of baseline liver, thyroid, and coagulation tests prior to initiation of therapy and routinely during therapy.
• Monitor blood glucose in patients with diabetes.
• Monitor patient's mental status: affect, mood, depression, behavioral changes.
• Notify health care provider if any of these symptoms occur: pain in calves accompanied by swelling, warmth and redness; severe sudden headache; visual disturbances; numbness in extremities; signs of depression; signs of liver dysfunction (eg, dark urine, jaundice); breakthrough bleeding.

 Patient/Family Education

• Caution patient that this medication must not be taken during pregnancy or when pregnancy is possible. Advise patient to use reliable form of birth control while taking this drug.
• Explain potential significance of breakthrough bleeding, irregular menstrual cycles, and possible lack of menstrual cycle. Tell patient to notify health care provider of heavy or continuous menstrual flow.
• Encourage patients with diabetes to monitor blood glucose more frequently until effect on diabetes control has been determined.
• Instruct patient to report these symptoms to health care provider: pain in calves of legs with redness, warmth and swelling; sudden severe headache; visual disturbances; numbness in extremities; dyspnea; chest pain; edema; jaundice; dark urine; clay-colored stools.
• Caution patient to avoid exposure to sunlight and other sources of ultraviolet light and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.

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