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# Megestrol Acetate ## Overview Megestrol acetate is a synthetic progestin used primarily for palliative treatment of advanced breast cancer and anorexia/cachexia associated with AIDS. ## Primary Indications * Treatment of advanced, metastatic breast cancer in postmenopausal women. * Treatment of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS). ## Adult Dosing * **Breast Cancer:** 160 mg (40 mL) by mouth once daily. Higher doses (e.g., 400-1600 mg/day) have been used but offer no clear advantage and increased side effects. * **AIDS Cachexia/Anorexia:** 400-800 mg (10-20 mL) by mouth once daily. ## Pediatric Dosing There is no established pediatric dosing. Use is generally not recommended. ## Dose Adjustments * **Hepatic Impairment:** No specific guidelines, but caution is advised due to potential for hepatic metabolism. * **Renal Impairment:** No specific guidelines. ## Contraindications * Known or suspected pregnancy. * Known hypersensitivity to megestrol acetate. ## Adverse Effects * **Common:** Weight gain, increased appetite, hot flashes, hypertension, edema, nausea, diarrhea, rash, dyspnea, vaginal bleeding, impotence, decreased libido. * **Serious:** Adrenal insufficiency (especially with abrupt discontinuation after prolonged use), thromboembolic events (deep vein thrombosis, pulmonary embolism), hyperglycemia, Stevens-Johnson syndrome. ## Key Drug Interactions * **Aminoglutethimide:** May decrease megestrol plasma concentrations. * **CYP3A4 Inhibitors/Inducers:** May alter megestrol plasma concentrations. ## Monitoring * Weight and appetite status. * Signs and symptoms of adrenal insufficiency (fatigue, weakness, nausea, vomiting, hypotension). * Thromboembolic events. * Blood glucose in diabetic patients. * Blood pressure. ## Clinical Pearls * Abrupt discontinuation after prolonged high-dose therapy may lead to adrenal insufficiency. Tapering may be necessary. * Weight gain is a common and often desired effect in cachectic patients. * Use caution in patients with a history of thromboembolic events. * The oral suspension contains sucrose and may not be suitable for patients with sucrose intolerance or diabetes if large volumes are consumed. *** *This information is intended for healthcare professionals. Please consult the most current prescribing information for complete details and to verify dosage and safety before initiating therapy.*