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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestin with antineoplastic and antiestrogenic properties.
## Primary Indications
* Management of advanced breast cancer (palliative).
* Management of advanced endometrial carcinoma (palliative).
* Appetite stimulation and weight gain in patients with cachexia or unexplained weight loss associated with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Cancer:** 160 mg orally once daily.
* **Endometrial Carcinoma:** 40 mg orally two to four times daily. Doses up to 100 mg orally four times daily have been used. Treatment is generally continued until disease progression.
* **Cachexia/Anorexia (AIDS):** 400-800 mg orally once daily. Doses of 800 mg daily are often considered more effective for weight gain.
## Pediatric Dosing
There is no established pediatric dosing.
## Dose Adjustments
* **Hepatic Impairment:** No specific adjustments are established. Use with caution.
* **Renal Impairment:** No specific adjustments are established. Use with caution.
## Contraindications
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Pregnancy.
## Adverse Effects
* **Common:** Weight gain, increased appetite, hypertension, hot flashes, nausea, vomiting, diarrhea, dyspnea, peripheral edema, rash, fatigue, and tumor flare.
* **Serious:** Adrenal insufficiency, thromboembolic events (deep vein thrombosis, pulmonary embolism), hyperglycemia, and cataracts.
## Key Drug Interactions
* **Aminoglutethimide:** May decrease megestrol acetate concentrations.
* **CYP3A4 Inhibitors/Inducers:** May alter megestrol acetate concentrations; monitor for efficacy and toxicity.
## Monitoring
* Blood pressure.
* Electrolytes, especially in patients with cachexia.
* Blood glucose, particularly in patients with diabetes or risk factors.
* Signs and symptoms of thromboembolic events.
* Vision for cataract development.
* Adrenal function, especially with abrupt discontinuation or in patients with concurrent corticosteroid use.
## Clinical Pearls
* Significant weight gain and increased appetite are expected and often the desired effect in AIDS-associated cachexia.
* Abrupt discontinuation may precipitate adrenal insufficiency, especially if the patient is also on corticosteroids. Tapering may be considered.
* Consider screening for cataracts, especially with prolonged use.
* Increased risk of opportunistic infections has been reported, particularly in patients with AIDS.
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**Disclaimer:** This information is intended for clinical pharmacy professionals. Always consult the current prescribing information and relevant clinical guidelines before making any therapeutic decisions. Dosing may vary based on individual patient factors and local institutional protocols.
