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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestogen. It is available in oral suspension and tablet formulations.
## Primary Indications
* Palliative treatment of advanced carcinoma of the breast in postmenopausal women.
* Palliative treatment of advanced, recurrent or metastatic carcinoma of the endometrium.
* Management 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 Cancer:** 40 mg orally four times daily. Doses of 40-320 mg daily have been used. Treatment is typically continued until progression of the disease.
* **AIDS-Related Anorexia/Cachexia/Weight Loss:** 800 mg orally once daily. Lower doses (e.g., 400 mg daily) may be considered for maintenance.
## Pediatric Dosing
No established pediatric dosing recommendations exist.
## 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, increased appetite, hot flashes, nausea, vomiting, diarrhea, vaginal bleeding, edema, hypertension, shortness of breath, rash, and alopecia.
* **Serious:** Thrombotic events (e.g., deep vein thrombosis, pulmonary embolism), adrenal insufficiency (particularly with abrupt withdrawal after prolonged use), hyperglycemia, and new-onset diabetes.
## Key Drug Interactions
* **CYP3A4 Inducers:** Drugs that induce CYP3A4 (e.g., rifampin, phenytoin, carbamazepine) may decrease megestrol acetate concentrations.
* **CYP3A4 Inhibitors:** Drugs that inhibit CYP3A4 (e.g., ketoconazole, itraconazole) may increase megestrol acetate concentrations.
* **Aminoglutethimide:** May decrease megestrol acetate concentrations.
## Monitoring
* Regular monitoring of weight, appetite, and nutritional status.
* Monitor for signs and symptoms of adrenal insufficiency, particularly with prolonged use or withdrawal.
* Monitor blood glucose levels, especially in patients with diabetes or risk factors for diabetes.
* Monitor for signs and symptoms of thrombotic events.
* Periodic assessment for tumor response.
## Clinical Pearls
* For AIDS-related anorexia/cachexia, the 800 mg daily dose is generally preferred for initial management due to greater efficacy.
* Abrupt discontinuation after prolonged use may lead to adrenal insufficiency. Gradual tapering may be necessary.
* Megestrol acetate can cause significant fluid retention. Monitor for edema and new or worsening heart failure.
* Women of childbearing potential should use effective contraception during treatment.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the official prescribing information and relevant clinical guidelines for complete details and to verify current recommendations before making therapeutic decisions.
