Megace (Megestrol Acetate)

Megace is a synthetic progestogen used in conditions where appetite stimulation or hormonal control of tumor growth is required.

• Cachexia associated with AIDS or cancer: improves appetite and promotes weight gain.
• Advanced breast cancer: provides antineoplastic activity as part of hormone therapy.
• Endometrial cancer: used as hormonal treatment to inhibit tumor growth.

• Megestrol acetate acts as a synthetic progestin that binds to progesterone receptors, modulating gene transcription that leads to antineoplastic effects. Its glucocorticoid‑like activity also influences hypothalamic pathways, enhancing appetite and reducing catabolic processes associated with cachexia.

Megace may cause a range of adverse reactions, ranging from mild to serious.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Weight gain: due to increased appetite and fluid retention.
• Edema: peripheral swelling, especially in the lower extremities.
• Fatigue: generalized tiredness.
• Hot flashes: transient vasomotor symptoms.
• Mood changes: irritability or mild depression.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Adrenal suppression: signs of cortisol deficiency.
• Hyperglycemia: elevated blood glucose levels, particularly in diabetic patients.
• Hepatotoxicity: abnormal liver function tests.
• Severe allergic reaction: rash, itching, swelling, or difficulty breathing.

Before initiating Megace, clinicians should assess patient history and monitor for potential risks.

• Assess thrombotic risk: evaluate history of clotting disorders.
• Monitor blood glucose: check fasting glucose in diabetic or pre‑diabetic patients.
• Evaluate liver function: perform baseline hepatic enzymes.
• Review hormonal status: consider effects on menstrual cycle and fertility.
• Caution in pregnancy: avoid use unless benefits outweigh risks.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture and light.

Megace can alter the activity of several co‑administered medicines; interaction severity varies.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): increased risk of bleeding.
• CYP3A4 inducers (e.g., rifampin): may reduce Megace plasma levels.
• CYP3A4 inhibitors (e.g., ketoconazole): may increase Megace exposure.

Moderate Interactions (Monitor Closely)

• Insulin or oral hypoglycemics: potential for altered glucose control.
• Other hormonal agents: additive endocrine effects.
• NSAIDs: heightened risk of gastrointestinal irritation.