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# Megestrol Acetate (Megace ES)
## Overview
Megestrol acetate is a synthetic progestin with antineoplastic and antiestrogenic properties.
## Primary Indications
* Treatment of cachexia, anorexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
* Palliative treatment of advanced carcinoma of the breast or endometrium.
## Adult Dosing
* **AIDS-related cachexia:** 625 mg (25 mL) orally once daily. May be increased to 1250 mg (50 mL) once daily if not gaining weight.
* **Breast/Endometrial Cancer:** 40 mg orally four times daily (160 mg/day). Higher doses (e.g., 80 mg four times daily) have been used.
## Pediatric Dosing
No established pediatric dosing. Use in pediatric patients is not recommended due to lack of safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment recommended.
* **Hepatic Impairment:** No specific dose adjustment recommended, but caution advised.
## Contraindications
* Known or suspected pregnancy.
* Known hypersensitivity to megestrol acetate or any of its components.
## Adverse Effects
* **Common:** Weight gain, increased appetite, hot flashes, rash, diarrhea, nausea, hypertension, dyspnea, headache, abdominal pain, fatigue.
* **Serious:** Adrenal insufficiency, thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism), hyperglycemia, Stevens-Johnson syndrome, toxic epidermal necrolysis, tumor flare.
## Key Drug Interactions
* **Aminoglutethimide:** May decrease megestrol acetate plasma concentrations.
* **CYP3A4 Inhibitors/Inducers:** May alter megestrol acetate plasma concentrations. Monitor for efficacy and toxicity.
* **Dofetilide:** Megestrol acetate may increase dofetilide concentrations, increasing the risk of serious ventricular arrhythmias.
## Monitoring
* Weight and appetite.
* Electrolytes, glucose, and adrenal function, especially in patients with risk factors for adrenal insufficiency or during prolonged therapy.
* Signs and symptoms of thromboembolic events.
* Tumor response in cancer patients.
## Clinical Pearls
* Significant weight gain is expected and is a primary efficacy endpoint in AIDS-related cachexia.
* Administer with food to improve absorption and tolerability.
* Monitor for adrenal insufficiency, particularly if the drug is discontinued abruptly after long-term use, as it can suppress the hypothalamic-pituitary-adrenal axis.
* Use caution in patients with a history of thromboembolic disease.
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**Disclaimer:** This information is intended for healthcare professionals and does not substitute for professional medical advice. Always consult the most current prescribing information or a qualified healthcare provider for diagnosis and treatment.
