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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestin with antineoplastic and antiestrogenic activity. It is also known to stimulate appetite.
## Primary Indications
* Management of advanced breast cancer (in postmenopausal women or women with surgically castrated men).
* Management of advanced endometrial cancer.
* Treatment of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Cancer:** 160 mg (400 mg/day orally) orally once daily.
* **Endometrial Cancer:** 40 mg (40-320 mg/day orally) orally 1-4 times daily.
* **AIDS-associated Anorexia/Cachexia/Weight Loss:** 800 mg orally once daily. A dose of 400 mg orally once daily may be sufficient for some patients.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are recommended, but caution may be warranted.
* **Hepatic Impairment:** No specific dose adjustments are recommended, but caution may be warranted.
## Contraindications
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Pregnancy.
## Adverse Effects
* **Common:** Weight gain, increased appetite, hypertension, hot flashes, dyspnea, nausea, vomiting, diarrhea, headache, rash, carpal tunnel syndrome.
* **Serious:** Thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism), adrenal insufficiency, hyperglycemia, vaginal bleeding (unexpected), new onset or worsening of depression, vision disturbances.
## Key Drug Interactions
* **CYP3A4 Inhibitors:** May increase megestrol acetate concentrations. Monitor for increased adverse effects.
* **CYP3A4 Inducers:** May decrease megestrol acetate concentrations. Monitor for decreased efficacy.
* **Aminoglutethimide:** May decrease megestrol acetate serum concentrations.
* **Antidiabetic Agents:** Megestrol acetate may cause hyperglycemia; monitor blood glucose closely and adjust antidiabetic therapy as needed.
## Monitoring
* Blood pressure.
* Electrolytes.
* Blood glucose (especially in patients with diabetes or at risk).
* Signs and symptoms of thromboembolic events.
* Signs and symptoms of adrenal insufficiency (if stopped abruptly).
* Weight and appetite.
* For women of childbearing potential, rule out pregnancy before initiating therapy.
## Clinical Pearls
* Megestrol acetate can cause significant weight gain and increased appetite, which can be beneficial in patients with cachexia.
* The risk of thromboembolic events, adrenal insufficiency, and hyperglycemia should be discussed with patients.
* Abrupt discontinuation may lead to adrenal insufficiency, especially if patients have been on long-term therapy or have underlying adrenal issues. Tapering may be necessary.
* Oral suspension formulations are available and may be preferred for ease of administration.
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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 guidelines before making any clinical decisions. Local protocols may dictate specific dosing and management.
