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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic derivative of progesterone with antineoplastic and anti-anorectic properties. It is a potent progestin.
## Primary Indications
* Palliative treatment of advanced endometrial carcinoma.
* Treatment of cachexia, anorexia, or unexplained significant weight loss in patients with acquired immunodeficiency syndrome (AIDS).
## Adult Dosing
* **Endometrial Carcinoma:** 40 mg orally four times daily. Alternatively, 40-320 mg orally once daily.
* **AIDS-related Cachexia/Anorexia:** 800 mg orally once daily.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate.
## Dose Adjustments
Dose adjustments are typically based on patient response and tolerability. Dose reductions may be considered for side effects.
## Contraindications
* Known hypersensitivity to megestrol acetate or any of its components.
* Pregnancy.
* Undiagnosed abnormal vaginal bleeding.
* History of thrombophlebitis or thromboembolic disorders.
## Adverse Effects
Common adverse effects include: weight gain, nausea, vomiting, diarrhea, abdominal pain, hot flashes, hypertension, rash, edema, headache, and mood changes.
Serious adverse effects can include: thromboembolic events (deep vein thrombosis, pulmonary embolism, stroke), adrenal insufficiency, hyperglycemia, and visual disturbances.
## Key Drug Interactions
* **CYP3A4 inhibitors (e.g., ketoconazole, ritonavir):** May increase megestrol acetate concentrations. Monitor for increased adverse effects.
* **CYP3A4 inducers (e.g., rifampin, phenytoin, St. John's Wort):** May decrease megestrol acetate concentrations.
## Monitoring
* **For Endometrial Carcinoma:** Monitor for tumor response.
* **For AIDS-related Cachexia/Anorexia:** Monitor weight, appetite, and nutritional status.
* **General:** Monitor for signs and symptoms of thromboembolic events, adrenal insufficiency (especially if withdrawn abruptly or in times of stress), and hyperglycemia. Baseline and periodic laboratory assessments may be indicated based on patient's condition.
## Clinical Pearls
* Administer with food to improve absorption and reduce gastrointestinal upset.
* Do not abruptly discontinue medication, especially in patients with adrenal insufficiency, to avoid precipitating adrenal crisis. Taper dose gradually.
* Weight gain is a common and often desired effect in cachectic patients, but can be significant and accompanied by fluid retention.
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**Disclaimer:** This information is intended for clinical decision-making and does not replace comprehensive drug information resources or professional judgment. Always consult the most current prescribing information and relevant guidelines for complete and up-to-date details.
