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# Megestrol Acetate (Megace ES)
## Overview
Megestrol acetate is a synthetic progestin with antineoplastic and antiestrogenic properties. It is also known to stimulate appetite.
## Primary Indications
* Treatment of cachexia, anorexia, or unexplained significant weight loss associated with acquired immunodeficiency syndrome (AIDS).
* Palliative treatment of advanced carcinoma of the breast or endometrium.
## Adult Dosing
* **AIDS-related anorexia/cachexia:** 400-800 mg orally once daily. Higher doses may be needed for optimal appetite stimulation, but efficacy beyond 800 mg/day is not well established.
* **Breast cancer:** 160 mg orally once daily.
* **Endometrial cancer:** 40 mg orally four times daily (160 mg/day). Alternatively, 40-320 mg orally once daily.
## Pediatric Dosing
* Safety and efficacy in pediatric patients have not been established.
## Dose Adjustments
* No specific dose adjustments are recommended for renal or hepatic impairment. However, caution should be exercised in patients with hepatic impairment due to potential for liver toxicity.
## Contraindications
* Known or suspected pregnancy.
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Diagnosis of a thromboembolic disorder or history thereof.
## Adverse Effects
* **Common:** Weight gain (often due to fluid retention), nausea, vomiting, diarrhea, hot flashes, abdominal pain, headache, fatigue, hypertension, rash, and dyspnea.
* **Serious:** Adrenal insufficiency, hyperglycemia, thromboembolic events (e.g., pulmonary embolism, deep vein thrombosis), new-onset diabetes, and exacerbation of existing diabetes, Cushing's syndrome, and loss of libido.
## Key Drug Interactions
* **Aminoglutethimide:** May decrease the serum concentrations of megestrol acetate.
* **CYP3A4 inhibitors/inducers:** May alter megestrol acetate concentrations.
## Monitoring
* Weight and appetite.
* Electrolytes, glucose, and signs of adrenal insufficiency, particularly in patients with risk factors.
* Signs and symptoms of thromboembolic events.
* Liver function tests.
## Clinical Pearls
* Oral suspension formulations should be shaken well before use.
* Appetite stimulation may take several weeks to become apparent.
* Discontinue if thromboembolic events occur.
* Women of childbearing potential should use effective contraception.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions. Dosages and recommendations may vary based on individual patient factors and local protocols.
