Megace (Megestrol Acetate)

Megace (megestrol acetate) is used in clinical settings that involve hormone‑dependent disease pathways and severe weight loss.

• Cachexia associated with AIDS or cancer: stimulates appetite and promotes weight gain in patients experiencing severe wasting.
• Advanced breast cancer: provides hormonal therapy that can help slow tumor progression in estrogen‑responsive disease.
• Endometrial cancer: used as a progestogenic agent to inhibit disease progression in selected cases.

• Megestrol acetate is a synthetic progestin that binds to intracellular progesterone receptors, producing anti‑estrogenic effects in hormone‑sensitive tissues. Its glucocorticoid‑like activity also modulates hypothalamic pathways that regulate appetite, leading to increased food intake and weight gain while influencing tumor growth in certain cancers.

Megace may cause a range of adverse reactions, which are grouped by frequency and severity.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Vomiting: occasional emesis.
• Weight gain: increase in body mass, sometimes fluid‑related.
• Edema: peripheral swelling.
• Fatigue: feeling of tiredness.
• Hot flashes: transient warmth and sweating.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Adrenal insufficiency: signs of cortisol deficiency.
• Severe infection: opportunistic bacterial or fungal infections.
• Cushingoid appearance: facial rounding and skin changes.
• Hyperglycemia: elevated blood glucose levels.
• Hepatotoxicity: abnormal liver function tests.

Before initiating Megace, clinicians should consider several safety measures to minimize risk.

• Monitor blood glucose: check for hyperglycemia, especially in diabetic patients.
• Assess lipid profile: watch for increases in cholesterol and triglycerides.
• Evaluate thromboembolic risk: avoid use in patients with history of clotting disorders.
• Review adrenal function: consider potential suppression of cortisol production.
• Use caution in hepatic impairment: adjust monitoring if liver disease is present.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Megace can interact with other medicines, requiring attention to the level of interaction.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): increased bleeding risk.
• Antiretroviral protease inhibitors: altered metabolism leading to unpredictable levels.
• CYP3A4 inducers (e.g., rifampin, phenytoin): reduced efficacy of megestrol acetate.
• Systemic corticosteroids: additive glucocorticoid effects.
• Hormonal contraceptives: decreased contraceptive effectiveness.

Moderate Interactions (Monitor Closely)

• Antidiabetic agents: may require dose adjustment due to hyperglycemia.
• Antihypertensives: potential fluid retention can affect blood pressure control.
• Digoxin: monitor serum levels for possible increase.
• Thyroid hormones: assess for altered thyroid function tests.