Megace (Megestrol Acetate)

Megace is a synthetic progestin used in the management of conditions that involve weight loss, hormonal‑driven tumours, or appetite decline.

• Cachexia associated with AIDS or cancer: helps increase appetite and promote weight gain.
• Anorexia: stimulates hunger signals to improve nutritional intake.
• Breast cancer: used as an antineoplastic hormone to inhibit tumour growth.
• Endometrial cancer: provides hormonal therapy to control disease progression.

• Megestrol acetate acts as an agonist at progesterone receptors, producing antigonadotropic effects that lower circulating estrogen levels. The reduction in estrogen contributes to tumour control in hormone‑sensitive cancers, while activation of central pathways in the hypothalamus enhances appetite, leading to improved caloric intake and weight gain.

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

Common Side Effects

• Weight gain: excess caloric retention.
• Edema: fluid accumulation, especially in lower extremities.
• Nausea or vomiting: gastrointestinal discomfort.
• Fatigue: general tiredness or weakness.
• Hot flashes: transient flushing episodes.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Adrenal insufficiency: cortisol deficiency on abrupt discontinuation.
• Hyperglycaemia: elevated blood glucose, may precipitate diabetes.
• Hepatotoxicity: liver enzyme abnormalities.
• Severe allergic reactions: rash, angioedema, or anaphylaxis.

Before initiating therapy, clinicians should evaluate patient history and monitor for potential complications.

• Assess baseline weight and nutritional status: document changes during treatment.
• Monitor blood glucose and lipid profiles: detect hyperglycaemia or dyslipidaemia.
• Evaluate for signs of thrombosis: watch for leg swelling or chest pain.
• Review concomitant corticosteroid use: increased risk of adrenal suppression.
• Store at ambient temperature below 25 °C: keep in original packaging, protect from moisture and direct sunlight.

Megace can interact with several drug classes, requiring careful management.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): may enhance bleeding risk.
• CYP3A4 inducers (e.g., rifampin, phenytoin): can reduce megesterol levels.

Moderate Interactions (Monitor Closely)

• Antidiabetic agents: may require dose adjustment due to hyperglycaemia.
• Corticosteroids: combined use increases risk of adrenal insufficiency on withdrawal.
• Hormonal therapies (e.g., tamoxifen): may alter hormonal balance and efficacy.