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# Megestrol Acetate (Megace ES, Megace)
## Overview
Megestrol acetate is a synthetic progestational drug.
## Primary Indications
* Management of cachexia, anorexia, or unexplained significant weight loss in the palliative care setting.
* Treatment of advanced breast cancer (hormone-responsive).
* Treatment of advanced endometrial cancer (hormone-responsive).
## Adult Dosing
* **Cachexia/Anorexia/Weight Loss:**
* Oral suspension: 625 mg (5 mL) by mouth once daily. Higher doses may be considered.
* Tablets: 800 mg by mouth once daily or 400 mg by mouth once or twice daily.
* **Advanced Breast Cancer:** 160 mg by mouth once daily.
* **Advanced Endometrial Cancer:** 40 mg by mouth 4 times daily (160 mg/day total).
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate. Use is generally not recommended.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is recommended.
* **Hepatic Impairment:** No specific dose adjustment is recommended, but caution is advised.
## Contraindications
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Pregnancy.
## Adverse Effects
* **Common:** Weight gain (often desirable in cachexia), hot flashes, hypertension, dyspnea, nausea, vomiting, diarrhea, abdominal pain, rash, edema, thrombocytopenia, alopecia.
* **Serious:** Adrenal insufficiency (especially with prolonged use and abrupt discontinuation), hyperglycemia, thromboembolic events (deep vein thrombosis, pulmonary embolism), Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **CYP3A4 Inhibitors/Inducers:** May alter megestrol acetate concentrations. Monitor for efficacy and adverse effects.
* **Corticosteroids:** Concurrent use may increase the risk of adrenal insufficiency.
## Monitoring
* **Weight:** Monitor regularly, especially in patients receiving treatment for cachexia/anorexia.
* **Adrenal Function:** Monitor for signs and symptoms of adrenal insufficiency (fatigue, weakness, nausea, vomiting, hypotension) especially with prolonged use and after discontinuation. Consider baseline and periodic adrenal function testing.
* **Blood Pressure:** Monitor regularly.
* **Glucose:** Monitor for hyperglycemia, especially in patients with diabetes or risk factors.
* **Thromboembolic Events:** Monitor for signs and symptoms (e.g., leg pain, swelling, chest pain, shortness of breath).
## Clinical Pearls
* Abrupt discontinuation of megestrol acetate after prolonged therapy may lead to adrenal insufficiency. Taper dose gradually.
* Use of the oral suspension may be preferred for easier administration and potentially better absorption in some patients.
* Dosing for cachexia/anorexia is often higher and may be titrated based on patient response and tolerability. The maximum dose is not well-defined and should be guided by clinical judgment.
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*This information is intended for healthcare professionals. Please verify current prescribing information and consult relevant clinical guidelines before initiating or modifying therapy.*
