Nurses Compass
Drug Guide
Megestrol Acetate
Classification
Therapeutic: Antineoplastic, Appetite stimulant
Pharmacological: Progestin
FDA Approved Indications
- Advanced carcinoma of the endometrium
- Palliative management of breast cancer
- Cachexia or anorexia associated with AIDS or cancer
Mechanism of Action
Megestrol acetate is a synthetic progestin that acts on progesterone receptors, leading to changes in hormone levels that inhibit tumor growth and stimulate appetite.
Dosage and Administration
Adult: Palliative or cachexia: 400-800 mg daily, divided into 2-4 doses; endometrial cancer: 40 mg daily.
Pediatric: Not typically used in pediatric patients.
Geriatric: Dose adjustments based on tolerance; generally similar to adult dosing, with careful monitoring.
Renal Impairment: Use with caution; no specific dose adjustment recommended but monitor renal function.
Hepatic Impairment: Use with caution; liver function should be monitored.
Pharmacokinetics
Absorption: Well absorbed after oral administration.
Distribution: Extensively bound to plasma proteins, mainly albumin.
Metabolism: Primarily metabolized in the liver via hydroxylation and conjugation.
Excretion: Excreted mainly via urine and feces.
Half Life: Approximately 16-20 hours.
Contraindications
- Known hypersensitivity to megestrol acetate or any component of the formulation.
- Pregnancy (category X)
Precautions
- Monitor for thromboembolic events, hepatic dysfunction, or adrenal insufficiency.
Adverse Reactions - Common
- Weight gain, edema (Common)
- Nausea, diarrhea (Common)
Adverse Reactions - Serious
- Venous thromboembolism, heart attack, stroke (Serious but less common)
- Hepatotoxicity, adrenal suppression (Rare)
Drug-Drug Interactions
- Anticoagulants (may increase bleeding risk)
- Insulin or antidiabetics (altered glucose control)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor weight, fluid retention, liver function tests, and signs of thromboembolic events.
Diagnoses:
- Impaired nutrition related to decreased appetite or adverse effects.
- Risk for thromboembolic event.
Implementation: Administer with food to reduce GI upset; monitor for adverse reactions.
Evaluation: Assess improvement in appetite, weight, and overall condition.
Patient/Family Teaching
- Take medication as prescribed and do not stop abruptly.
- Report signs of blood clots, such as swelling, pain, or shortness of breath.
- Avoid smoking and maintain regular check-ups.
Special Considerations
Black Box Warnings:
- Risk of thromboembolic events and fatalities; use with caution in patients with a history of thromboembolism.
Genetic Factors: N/A
Lab Test Interference: May interfere with hormone assays.
Overdose Management
Signs/Symptoms: Nausea, vomiting, dizziness, rapid weight gain, edema.
Treatment: Supportive care; consider gastric lavage or activated charcoal if ingestion is recent; symptomatic treatment.
Storage and Handling
Storage: Store at room temperature, away from moisture and light.
Stability: Stable under recommended storage conditions.