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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic derivative of progesterone used in oncology for its antiandrogenic and antineoplastic effects, and for its appetite-stimulating properties.
## Primary Indications
* Palliative treatment of advanced breast carcinoma in postmenopausal women.
* Palliative treatment of advanced endometrial carcinoma.
* Management of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Carcinoma:** 160 mg orally once daily.
* **Endometrial Carcinoma:** 40 mg orally four times daily (total 160 mg daily).
* **Anorexia/Cachexia in AIDS:** 400-800 mg orally once daily.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment recommendations.
* **Hepatic Impairment:** No specific dose adjustment recommendations. Use with caution.
## Contraindications
* Known hypersensitivity to megestrol acetate or any of its components.
* Pregnancy and breastfeeding.
## Adverse Effects
* **Common:** Weight gain, increased appetite, hot flashes, dyspnea, nausea, vaginal bleeding, edema, hypertension.
* **Less Common/Serious:** Thromboembolic events (deep vein thrombosis, pulmonary embolism), adrenal insufficiency (especially upon withdrawal), hyperglycemia, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **CYP3A4 Inhibitors/Inducers:** May alter megestrol acetate plasma concentrations. Monitor for efficacy and toxicity.
* **Adrenal Agents:** May mask signs of adrenal insufficiency.
## Monitoring
* **Tumor Response:** Clinical assessment, imaging as appropriate.
* **Weight and Appetite:** Regular monitoring, especially in AIDS patients.
* **Signs of Thromboembolism:** Assess for leg pain, swelling, shortness of breath.
* **Adrenal Function:** Monitor for symptoms of adrenal insufficiency, especially during dose reduction or withdrawal.
* **Blood Glucose:** Especially in patients with diabetes or at risk.
## Clinical Pearls
* For anorexia/cachexia, higher doses (400-800 mg daily) are generally required for appetite stimulation.
* Abrupt discontinuation may precipitate adrenal insufficiency. Taper dose gradually if possible.
* Megestrol acetate can cause significant weight gain due to increased appetite; this may be desirable in cachectic patients but needs management in others.
* Use with caution in patients with a history of thromboembolic disease.
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*This information is intended for healthcare professionals. Always verify the most current prescribing information and consult relevant clinical guidelines before making treatment decisions.*
