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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestogen derivative used for its palliative and appetite-stimulating effects.
## Primary Indications
* Management of cachexia, anorexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
* Palliative treatment of recurrent, inoperable carcinoma of the breast in postmenopausal women.
* Palliative treatment of endometrial carcinoma.
## Adult Dosing
* **AIDS-related anorexia/cachexia:** 800 mg orally once daily. Higher doses (e.g., 400-1200 mg/day) have been used, but 800 mg daily is generally considered optimal.
* **Breast cancer:** 160 mg orally once daily.
* **Endometrial carcinoma:** 40 mg orally 4 times daily (160 mg/day). Continue treatment as long as the patient is benefiting.
## Pediatric Dosing
No established pediatric dosing. Use in pediatric populations is not recommended due to lack of data and potential risks.
## Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment, but caution is advised. Monitor patients closely for adverse effects.
## Contraindications
* Known or suspected pregnancy.
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Undiagnosed abnormal vaginal bleeding.
## Adverse Effects
* **Common:** Weight gain (due to fluid retention and appetite stimulation), hot flashes, hypertension, nausea, vomiting, diarrhea, dyspnea, rash, vaginal bleeding or discharge.
* **Serious:** Adrenal insufficiency, thromboembolic events (e.g., pulmonary embolism, deep vein thrombosis), hyperglycemia, liver dysfunction.
## Key Drug Interactions
* **CYP3A4 inhibitors (e.g., ketoconazole, ritonavir):** May increase megestrol acetate concentrations. Monitor for increased adverse effects.
* **CYP3A4 inducers (e.g., rifampin, phenytoin):** May decrease megestrol acetate concentrations. Monitor for decreased efficacy.
## Monitoring
* Weight and appetite.
* Blood pressure.
* Electrolytes, glucose, and liver function tests periodically.
* Signs and symptoms of thromboembolic events.
* Adrenal function, especially with prolonged use or abrupt discontinuation.
## Clinical Pearls
* Shake oral suspension well before use.
* Appetite stimulation and weight gain may take several weeks to become apparent.
* Withdrawal of megestrol acetate may result in a return of cachexia and anorexia.
* May cause adrenal suppression; do not abruptly discontinue, especially in patients with adrenal insufficiency. Taper dose if possible.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant literature for complete and up-to-date details.*
