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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestin with antineoplastic and antiestrogenic properties. It also has appetite-stimulating effects.
## Primary Indications
* Palliative treatment of advanced, recurrent, or metastatic breast cancer in postmenopausal women.
* Management of cachexia, anorexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Breast Cancer:** 160 mg orally once daily. Higher doses (e.g., 400-800 mg daily) have also been used.
* **Anorexia/Cachexia/Weight Loss (AIDS):** 400-800 mg orally once daily.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate. Its use in pediatric populations is generally not recommended due to lack of safety and efficacy data.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are typically recommended, but caution is advised.
* **Hepatic Impairment:** No specific dose adjustments are typically recommended, but caution is advised.
## Contraindications
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Diagnosis of or history of thromboembolic events (e.g., deep vein thrombosis, pulmonary embolism, stroke).
## Adverse Effects
* **Common:** Weight gain, increased appetite, hot flashes, hypertension, nausea, vomiting, diarrhea, abdominal pain, rash, dyspnea, fatigue, edema.
* **Serious:** Thromboembolic events (pulmonary embolism, deep vein thrombosis, stroke), adrenal insufficiency (especially with abrupt discontinuation after prolonged use), hyperglycemia, Cushing's syndrome, vaginal bleeding, fluid retention.
## Key Drug Interactions
* **CYP3A4 Inducers:** Drugs like rifampin, phenytoin, and carbamazepine may decrease megestrol acetate plasma concentrations.
* **CYP3A4 Inhibitors:** Drugs like ketoconazole and ritonavir may increase megestrol acetate plasma concentrations.
## Monitoring
* Weight and appetite.
* Blood pressure.
* Signs and symptoms of thromboembolic events.
* Electrolytes.
* Blood glucose, especially in diabetic patients.
* Adrenal function if discontinued abruptly after prolonged use, particularly in patients with underlying adrenal insufficiency or on concurrent corticosteroids.
## Clinical Pearls
* Gradual dose reduction is recommended if discontinuing after prolonged treatment, especially at high doses, to minimize the risk of adrenal insufficiency.
* The appetite-stimulating effect can be beneficial but may also contribute to significant weight gain and associated metabolic complications.
* While generally considered safe in postmenopausal women for breast cancer, the potential for thromboembolic events warrants careful patient selection and monitoring.
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*This information is intended for healthcare professionals. It is essential to consult the most current prescribing information and relevant clinical guidelines before initiating or modifying therapy. Local protocols may also dictate specific dosing or management strategies.*
