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# Megestrol Acetate (Megace)
## Overview
Megestrol acetate is a synthetic progestin derivative used for palliative treatment of certain cancers and to manage cachexia and anorexia.
## Primary Indications
* Treatment of advanced breast cancer.
* Treatment of advanced endometrial cancer.
* Management of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Cancer:** 160 mg (400 mL) orally once daily.
* **Endometrial Cancer:** 40 mg (100 mL) orally 4 times daily, or 40 mg (160 mg/mL suspension) orally 2 times daily. Alternatively, 800 mg orally once daily.
* **Anorexia/Cachexia/Weight Loss in AIDS:** 800 mg (20 mL of oral suspension) orally once daily. A lower dose of 400 mg orally daily has also been used.
## Pediatric Dosing
The safety and efficacy of megestrol acetate in pediatric patients have not been established.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised, and lower doses may be considered.
## Contraindications
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Pregnancy.
## Adverse Effects
* **Common:** Weight gain, increased appetite, nausea, vomiting, diarrhea, hot flashes, edema, dyspnea, abdominal pain, headache, insomnia, rash.
* **Serious:** Adrenal insufficiency (especially with abrupt withdrawal after prolonged use), thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism), hyperglycemia, new-onset diabetes, exacerbation of pre-existing diabetes, Cushing's syndrome, vaginal bleeding, pancreatitis.
## Key Drug Interactions
* **Aminoglutethimide:** May decrease megestrol acetate serum concentrations.
* **CYP3A4 Inhibitors/Inducers:** May alter megestrol acetate concentrations, though clinical significance is often unclear.
## Monitoring
* **Weight and appetite:** Assess for response and potential side effects.
* **Electrolytes:** Monitor sodium and potassium, especially with higher doses or prolonged use.
* **Blood glucose:** Monitor for hyperglycemia and diabetes, particularly in susceptible individuals.
* **Signs of thromboembolism:** Educate patients on symptoms of DVT and PE.
* **Adrenal function:** Consider assessment if abrupt discontinuation is planned after prolonged use, especially during times of stress.
* **Vaginal bleeding:** Monitor for changes.
## Clinical Pearls
* Oral suspension may be preferred for ease of administration and potentially better absorption.
* Weight gain is a common and often desired effect in patients with cachexia.
* Abrupt discontinuation after prolonged therapy can lead to adrenal insufficiency. Tapering may be necessary.
* Use with caution in patients with a history of thromboembolic events or those at risk.
* The long-term safety of megestrol acetate in younger patients or for prolonged non-oncologic indications requires careful consideration.
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**Disclaimer:** This information is intended for clinical use and does not substitute for comprehensive drug information resources. Always verify current prescribing information and institutional protocols before administration.
