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# Megestrol Acetate (Megace)
## Overview
Megestrol acetate is a synthetic progestin with anti-androgenic and anti-estrogenic properties. It also has appetite-stimulating effects.
## Primary Indications
* Treatment of cachexia, anorexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
* Palliative treatment of advanced endometrial carcinoma.
* Palliative treatment of advanced breast carcinoma.
## Adult Dosing
* **AIDS-related cachexia/anorexia:** 800 mg orally once daily. Higher doses (e.g., up to 1600 mg daily) have been used but may not offer additional benefit.
* **Endometrial carcinoma:** 40 mg orally four times daily (160 mg daily).
* **Breast carcinoma:** 160 mg orally once daily.
## Pediatric Dosing
The use of megestrol acetate in pediatric patients is not generally recommended due to lack of established efficacy and safety, and potential risks including adrenal suppression and growth retardation.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are recommended, but caution may be warranted in severe impairment.
* **Hepatic Impairment:** No specific dose adjustments are recommended, but caution may be warranted.
## Contraindications
* Known or suspected pregnancy.
* Known hypersensitivity to megestrol acetate or any component of the formulation.
* Undiagnosed abnormal vaginal bleeding.
## Adverse Effects
* **Common:** Weight gain (often due to fluid retention and increased appetite), hot flashes, hypertension, rash, diarrhea, nausea, abdominal pain, dyspnea, sexual dysfunction.
* **Less Common/Serious:** Thrombophlebitis, pulmonary embolism, adrenal insufficiency (especially with abrupt discontinuation after prolonged use), hyperglycemia, bone density loss, vaginal hemorrhage/discharge.
## Key Drug Interactions
* **CYP3A4 Inducers (e.g., rifampin, phenytoin, carbamazepine):** May decrease megestrol acetate concentrations.
* **CYP3A4 Inhibitors (e.g., ketoconazole, itraconazole):** May increase megestrol acetate concentrations.
* **Glucocorticoids:** Concurrent use may increase the risk of adrenal suppression.
## Monitoring
* Weight and nutritional status.
* Blood pressure.
* Blood glucose levels, particularly in patients with diabetes or risk factors.
* Signs and symptoms of thromboembolic events (e.g., leg swelling, shortness of breath, chest pain).
* Adrenal function if abrupt discontinuation is considered after prolonged high-dose therapy.
* For patients with advanced cancer, tumor response and signs of disease progression.
## Clinical Pearls
* Megestrol acetate can significantly increase appetite and lead to weight gain, which may be beneficial in cachexia but can be undesirable in other contexts.
* When used for advanced cancer, it is typically considered a palliative treatment.
* Abrupt discontinuation after prolonged use, particularly at higher doses, can lead to adrenal insufficiency. Tapering may be necessary.
* Use caution in patients with a history of thromboembolic disease.
* Oral suspension formulations are available and may be easier for some patients to take.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making therapeutic decisions. Local protocols may influence specific dosing.*
