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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestational drug. It is available in oral suspension and tablet formulations.
## Primary Indications
* Management of anorexia, cachexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
* Palliative treatment of advanced breast cancer (hormone-responsive).
* Palliative treatment of advanced endometrial carcinoma.
## Adult Dosing
**Anorexia/Cachexia (AIDS):**
* Oral suspension: 625 mg (25 mL) by mouth once daily.
* Tablets: Start with 625 mg by mouth once daily. May increase dose as needed.
**Advanced Breast Cancer:**
* 40 mg (1 tablet or 10 mL suspension) by mouth four times daily (total 160 mg/day).
* Alternatively: 160 mg by mouth once daily.
**Endometrial Carcinoma:**
* 40 mg (1 tablet or 10 mL suspension) by mouth four times daily (total 160 mg/day).
Dosing may be continued as long as the patient benefits. The optimal duration of therapy is not known.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate.
## Dose Adjustments
**Renal Impairment:** No specific dose adjustments are recommended.
**Hepatic Impairment:** No specific dose adjustments are recommended.
## Contraindications
* Known or suspected pregnancy.
* Known hypersensitivity to megestrol acetate or any component of the formulation.
## Adverse Effects
**Common:**
* Weight gain (often due to fluid retention)
* Increased appetite
* Hot flashes
* Diarrhea
* Nausea
* Rash
* Shortness of breath
* Hypertension
* Edema
**Serious:**
* Thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism)
* Adrenal insufficiency (especially with abrupt withdrawal after prolonged use)
* Hyperglycemia and exacerbation of diabetes mellitus
* Cushingoid symptoms (e.g., redistribution of body fat, moon face)
* Uterine bleeding
## Key Drug Interactions
* **CYP3A4 Inhibitors:** May increase megestrol acetate concentrations. Monitor for adverse effects.
* **CYP3A4 Inducers:** May decrease megestrol acetate concentrations. Efficacy may be reduced.
* **Antidiabetic medications:** Megestrol acetate can worsen glycemic control. Monitor blood glucose closely and adjust antidiabetic therapy as needed.
## Monitoring
* **Weight and appetite:** Regularly monitor for changes.
* **Signs of thromboembolic events:** Advise patients to report symptoms like leg pain, swelling, chest pain, or shortness of breath.
* **Blood glucose:** Particularly in patients with diabetes or at risk for hyperglycemia.
* **Adrenal function:** Consider monitoring cortisol levels if prolonged use is followed by abrupt discontinuation.
* **Signs of Cushingoid symptoms.**
## Clinical Pearls
* Megestrol acetate is indicated for symptomatic management of weight loss and anorexia, not as a primary treatment for the underlying disease.
* The oral suspension may be preferred for patients with difficulty swallowing.
* Abrupt discontinuation after prolonged therapy may lead to adrenal insufficiency. Tapering may be considered.
* Use with caution in patients with a history of thromboembolic events.
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**Disclaimer:** This information is intended for clinical use and does not replace comprehensive drug references. Always consult the most current prescribing information and professional resources for complete and up-to-date guidance.
