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# Megestrol Acetate
## Overview
Megestrol acetate is a synthetic progestin derivative used to treat various conditions, primarily related to hormone imbalances and appetite stimulation.
## Primary Indications
* **Cancer-related cachexia:** To promote weight gain and improve appetite in patients with advanced cancer.
* **Endometrial carcinoma:** Palliation of recurrent or metastatic disease.
* **Breast carcinoma:** Palliation of advanced, recurrent, or metastatic hormone-responsive breast cancer.
## Adult Dosing
* **Cancer-related cachexia:**
* Initial: 800 mg daily.
* Maintenance: Doses can be adjusted based on patient response, typically ranging from 400 mg to 800 mg daily.
* **Endometrial carcinoma:** 40 mg (10 mL) four times daily (160 mg/day).
* **Breast carcinoma:** 160 mg daily.
## Pediatric Dosing
There is no established pediatric dosing for megestrol acetate.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustments are routinely recommended, but caution is advised.
* **Hepatic Impairment:** No specific dose adjustments are routinely recommended, but caution is advised.
## Contraindications
* Known or suspected pregnancy.
* Undiagnosed abnormal vaginal bleeding.
* Known hypersensitivity to megestrol acetate or any of its components.
## Adverse Effects
* **Common:** Weight gain, increased appetite, nausea, vomiting, diarrhea, abdominal pain, headache, hot flashes, dyspnea, edema, hypertension, rash, alopecia, amenorrhea, breakthrough bleeding, vaginal hemorrhage, sexual dysfunction.
* **Serious:** Thrombophlebitis, pulmonary embolism, deep vein thrombosis, myocardial infarction, stroke, adrenal insufficiency (especially with abrupt discontinuation after prolonged use), new-onset diabetes, hyperglycemia, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir):** May increase megestrol acetate concentrations.
* **CYP3A4 inducers (e.g., rifampin, carbamazepine, phenytoin):** May decrease megestrol acetate concentrations.
* **Aminoglutethimide:** May decrease plasma concentrations of megestrol acetate.
* **Insulin or oral antidiabetic agents:** May require dose adjustments due to potential effects on glucose control.
## Monitoring
* **Weight and appetite:** Regularly assess for efficacy in cachexia.
* **Signs of thromboembolic events:** Monitor for leg pain/swelling, chest pain, shortness of breath.
* **Blood glucose:** Particularly in patients with diabetes or at risk.
* **Adrenal function:** Consider monitoring, especially with prolonged use and during periods of stress or illness, or upon discontinuation.
* **Hormonal effects:** Monitor for signs of menstrual irregularities, hot flashes.
## Clinical Pearls
* Megestrol acetate is a potent appetite stimulant; monitor weight gain closely to avoid excessive increases.
* Withdrawal symptoms, including adrenal insufficiency, can occur with abrupt discontinuation after prolonged use; consider gradual tapering.
* Advise patients of childbearing potential to use effective contraception.
* Do not use for the prevention of cardiovascular disease or dementia.
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**Disclaimer:** This information is intended for healthcare professionals and does not replace the need for consulting the official Prescribing Information and other relevant medical literature for the most current and complete drug information. Always verify current prescribing information with the manufacturer's approved labeling.
