Megace (Megestrol Acetate)

• Megestrol acetate is 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 in patients with severe wasting.
• Weight loss in chronic illness: helps restore body mass in individuals with disease‑related malnutrition.
• Advanced breast cancer: provides antineoplastic hormone therapy to slow tumor progression.
• Endometrial carcinoma: used as hormonal therapy to inhibit tumor growth.

• Megestrol acetate acts as a progesterone receptor agonist with additional glucocorticoid activity. By binding to intracellular progesterone receptors, it modulates gene transcription that reduces pro‑inflammatory cytokine production and alters metabolic pathways, leading to increased appetite and anabolic effects. The glucocorticoid component further suppresses catabolic signals, contributing to weight gain and, in hormone‑sensitive cancers, to inhibition of tumor cell proliferation.

Megestrol acetate may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Vomiting: occasional episodes of emesis.
• Edema: swelling of the lower extremities.
• Weight gain: excessive increase beyond therapeutic goal.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Adrenal suppression: reduced endogenous cortisol production.
• Severe allergic reaction: rash, swelling, or anaphylaxis.

• When prescribing Megestrol acetate, clinicians should consider several safety measures.
• Monitor weight: track changes to assess therapeutic response and avoid excessive gain.
• Assess glucose: check blood sugar regularly, especially in diabetic patients.
• Evaluate thrombotic risk: consider history of clotting disorders before initiating therapy.
• Review concomitant steroids: combined glucocorticoid effects may increase side‑effect burden.
• Pregnancy and lactation: use only if potential benefit justifies potential risk, as safety is not established.
• Store at ambient temperature: keep tablets in original container, protect from moisture and light.

Megestrol acetate can interact with other medicines, requiring attention to avoid reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): may enhance anticoagulant effect, increasing bleeding risk.
• CYP3A4 inducers (e.g., rifampin, phenytoin): can reduce plasma concentrations of megestrol acetate, decreasing efficacy.

Moderate Interactions (Monitor Closely)

• Corticosteroids: additive glucocorticoid activity may raise risk of hyperglycemia and adrenal suppression.
• Insulin or oral hypoglycemics: may require dose adjustment due to potential hyperglycemic effect.
• Hormonal therapies (e.g., tamoxifen): may interfere with hormonal balance; monitor clinical response.