Megace (Megestrol Acetate)

Megace is a progestin that acts on hormonal pathways to address cachexia and hormone‑sensitive cancers.

• Cachexia associated with AIDS or cancer: helps increase appetite and promote weight gain.
• Loss of appetite / weight loss: stimulates hunger and improves nutritional status.
• Endometrial cancer: provides anti‑neoplastic activity by modulating progesterone receptors.
• Breast cancer: used as hormone therapy in selected progesterone‑receptor positive cases.

• Megestrol acetate binds to progesterone receptors, acting as an agonist that exerts antigonadotropic effects and modest glucocorticoid activity. This receptor activation reduces catabolic signaling, enhances appetite, and can inhibit tumor growth in hormone‑sensitive cancers by altering cell proliferation pathways.

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

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Vomiting: occasional episodes, especially at treatment initiation.
• Diarrhea: loose stools that may affect hydration.
• Edema: peripheral swelling due to fluid retention.
• Weight gain: excessive increase beyond therapeutic goal.
• Fatigue: generalized tiredness.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Adrenal insufficiency: signs of cortisol deficiency.
• Cushing‑like syndrome: hyperglycemia, hypertension, and moon‑face appearance.
• Severe infection: opportunistic infections due to immunosuppression.
• Hepatic dysfunction: elevated liver enzymes or jaundice.

When prescribing Megace, clinicians should consider several safety measures.

• Monitor weight: assess for appropriate gain and avoid excessive accumulation.
• Assess blood glucose: watch for hyperglycemia, especially in diabetic patients.
• Evaluate thromboembolic risk: consider prophylaxis in high‑risk individuals.
• Review liver function: periodic tests to detect hepatic toxicity.
• Use caution in pregnancy: potential fetal risk requires risk‑benefit analysis.
• Store at ambient temperature: keep in the original pack, protect from moisture and direct sunlight.

Megace can interact with other medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole): may increase megestrol levels.
• Anticoagulants (e.g., warfarin): heightened risk of bleeding.
• Antidiabetic agents (e.g., insulin, sulfonylureas): may require dose reduction due to hyperglycemia.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, phenytoin): may reduce therapeutic effect.
• Systemic glucocorticoids: additive glucocorticoid activity.
• NSAIDs: increased risk of gastrointestinal irritation.