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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestin used to treat various conditions, including breast cancer, endometrial cancer, and cachexia associated with AIDS.
## Primary Indications
* **Breast Cancer:** Treatment of advanced or metastatic breast cancer.
* **Endometrial Cancer:** Treatment of advanced or metastatic endometrial cancer.
* **Cachexia/Anorexia:** Treatment of anorexia, cachexia, or unexplained weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Cancer:** Typically 160 mg by mouth once daily. Higher doses (e.g., 400-800 mg daily) have been used but are associated with increased toxicity.
* **Endometrial Cancer:** Typically 40 mg by mouth four times daily (total 160 mg daily).
* **Cachexia/Anorexia (AIDS):** Typically 800 mg by mouth once daily. Doses of 400 mg daily have also shown efficacy.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate. Use in pediatric patients is generally not recommended due to potential risks, including effects on growth and bone mineral density.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are typically recommended.
* **Hepatic Impairment:** No specific dose adjustments are typically recommended.
## Contraindications
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Pregnancy and breastfeeding.
* Use in patients with current or history of thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism, stroke) may be a relative contraindication, especially at higher doses.
## Adverse Effects
* **Common:** Weight gain, increased appetite, hot flashes, hypertension, dyspnea, nausea, diarrhea, edema, rash.
* **Serious:** Thromboembolic events (DVT, PE, stroke, MI), adrenal insufficiency (especially after prolonged use and abrupt withdrawal), hyperglycemia, cataracts, bone mineral density loss, tumor flare.
## Key Drug Interactions
* **CYP3A4 Inducers (e.g., rifampin, phenytoin, carbamazepine):** May decrease megestrol acetate concentrations.
* **CYP3A4 Inhibitors (e.g., ketoconazole, ritonavir):** May increase megestrol acetate concentrations.
* **Aminoglutethimide:** May decrease megestrol acetate concentrations.
## Monitoring
* Blood pressure.
* Weight and appetite.
* Signs and symptoms of thromboembolic events.
* Electrolytes.
* Blood glucose (especially in diabetics or those at risk).
* Signs of adrenal insufficiency upon discontinuation.
* Bone mineral density (with prolonged use).
* Ophthalmologic examinations (for cataracts).
## Clinical Pearls
* Weight gain and increased appetite are common and often desirable effects, particularly in cachectic patients.
* Sudden discontinuation after prolonged use can lead to adrenal insufficiency. Tapering the dose may be necessary.
* The risk of thromboembolic events, though less frequent than with some other hormonal agents, is a serious concern.
* Use with caution in patients with diabetes due to potential effects on glucose control.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols for complete guidance.*
