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# Megestrol Acetate (Megace)
## Overview
Megestrol acetate is a synthetic progestogen with antineoplastic and antiestrogenic properties. It is available in oral suspension and tablet formulations.
## Primary Indications
* Palliative treatment of advanced breast cancer in postmenopausal women.
* Palliative treatment of advanced endometrial carcinoma.
* Treatment of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Cancer:** 160 mg orally once daily.
* **Endometrial Carcinoma:** 40 mg orally 4 times daily (160 mg/day). Treatment can be continued as long as the patient is without progression of disease.
* **AIDS-associated Cachexia/Anorexia:** 800 mg orally once daily. Higher doses may be needed for appetite stimulation.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate. Its use in pediatric populations is generally not recommended due to lack of data and potential endocrine effects.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment guidelines are available. Use with caution.
* **Hepatic Impairment:** No specific dose adjustment guidelines are available. Use with caution.
## Contraindications
* Known or suspected pregnancy.
* Known hypersensitivity to megestrol acetate or any component of the formulation.
## Adverse Effects
* **Common:** Weight gain, increased appetite, hot flashes, hypertension, nausea, vomiting, diarrhea, abdominal pain, dyspnea, hair thinning/loss, rash, carpal tunnel syndrome.
* **Serious:** Adrenal insufficiency (especially with abrupt discontinuation), thromboembolic events (deep vein thrombosis, pulmonary embolism, stroke), hyperglycemia, adrenal suppression, tumor flare.
## Key Drug Interactions
* **Aminoglutethimide:** May decrease the plasma concentrations of megestrol acetate.
* **CYP3A4 Inhibitors/Inducers:** May alter megestrol acetate concentrations, though clinical significance is often unclear. Monitor for efficacy and toxicity.
## Monitoring
* **Tumor Response:** Clinical signs and symptoms, imaging studies as appropriate.
* **Weight and Appetite:** Regularly assess for signs of cachexia or significant weight loss.
* **Electrolytes:** Monitor sodium and potassium levels, especially in patients with adrenal insufficiency risk factors.
* **Blood Pressure:** Monitor for hypertension.
* **Thromboembolic Events:** Educate patients on signs and symptoms and monitor for any indicators.
* **Adrenal Function:** Consider monitoring cortisol levels if adrenal insufficiency is suspected, particularly with prolonged use or abrupt discontinuation.
## Clinical Pearls
* Can cause significant weight gain and appetite stimulation, which may be desirable in cachectic patients.
* Use with caution in patients with a history of thromboembolic disease.
* Abrupt discontinuation, especially after prolonged use, can lead to adrenal insufficiency. Tapering may be considered.
* May cause menstrual irregularities in premenopausal women.
* The oral suspension contains sucrose and may not be suitable for patients with diabetes or galactosemia.
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**Disclaimer:** This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and institutional protocols for complete and up-to-date guidance before making any clinical decisions.
