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# Megestrol Acetate ## Overview Megestrol acetate is a synthetic progestin derivative used primarily for its palliative effects in certain cancers and for appetite stimulation in cachexia. ## Primary Indications * Treatment of advanced breast cancer (palliative). * Treatment of advanced endometrial cancer (palliative). * Treatment of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS). ## Adult Dosing * **Breast Cancer:** 160 mg (400 mg/day is often used) orally once daily. * **Endometrial Cancer:** 40 mg orally 4 times daily (160 mg/day). * **AIDS-related Cachexia/Anorexia:** 800 mg orally once weekly or 400 mg orally twice weekly. Lower doses (e.g., 100-400 mg/day) have also been used. ## Pediatric Dosing There is no established pediatric dosing for megestrol acetate. Its use in pediatric populations is generally not recommended. ## Dose Adjustments * **Renal Impairment:** No specific dose adjustment recommendations. * **Hepatic Impairment:** No specific dose adjustment recommendations. ## Contraindications * Known or suspected pregnancy. * Known hypersensitivity to megestrol acetate or any component of the formulation. * Use in patients with AIDS-related cachexia for prevention of weight loss is not indicated. ## Adverse Effects * **Common:** Weight gain, increased appetite, hypertension, hot flashes, dyspnea, nausea, edema, abdominal pain, diarrhea, rash, headache. * **Serious:** Adrenal insufficiency, thromboembolic events (e.g., pulmonary embolism, deep vein thrombosis), hyperglycemia, cataracts, Stevens-Johnson syndrome, toxic epidermal necrolysis. ## Key Drug Interactions * **CYP3A4 Inducers (e.g., rifampin, phenytoin, carbamazepine):** May decrease megestrol acetate plasma concentrations. * **CYP3A4 Inhibitors (e.g., ketoconazole, ritonavir):** May increase megestrol acetate plasma concentrations. * **Antidiabetic agents:** May interfere with glucose control. ## Monitoring * Blood pressure. * Electrolytes. * Blood glucose. * Signs and symptoms of thromboembolic events. * Signs and symptoms of adrenal insufficiency. * Visual changes (for cataracts). * Weight and appetite changes. ## Clinical Pearls * Administer with food to improve absorption. * Weight gain is a common and often desired side effect in cachexia. * The risk of adrenal insufficiency can increase with prolonged use, especially upon abrupt discontinuation. * Use caution in patients with a history of thromboembolic events. * This drug is not a cure for cancer but a palliative agent. --- ***Disclaimer:** This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the most current prescribing information and your healthcare provider for any questions regarding medication use. Dosing can vary based on patient-specific factors and local protocols.