What are the contraindications to starting Megace (megestrol acetate)?

Contraindications to Starting Megestrol Acetate (Megace)

Megestrol acetate is contraindicated in patients with a history of hypersensitivity to the drug or any component of the formulation, and should be avoided in patients with high risk of thromboembolic events due to its significant association with increased mortality (RR 1.42), thromboembolic events (RR 1.84), and edema (RR 1.36). 1, 2

Absolute Contraindications

• History of hypersensitivity to megestrol acetate or any component of the formulation 1
• Concurrent use with dofetilide (due to drug interaction) 3

Relative Contraindications (High-Risk Conditions)

• History of thromboembolic disease
• Active thromboembolic disease
• High risk for thromboembolic events 2
• Sickle cell disease (case reports of paradoxical embolism) 4
• Patients with patent foramen ovale (increased risk of paradoxical embolism) 4
• Uncontrolled diabetes (risk of worsening hyperglycemia)
• Severe edema or conditions predisposing to fluid retention 2

Risk-Benefit Considerations

Megestrol acetate has been associated with several serious adverse effects that must be carefully considered:

1. Increased mortality risk (RR 1.42) 2
2. Thromboembolic events (RR 1.84) 2
3. Edema (RR 1.36) 2
4. Hyperglycemia/glucose intolerance requiring close monitoring 2

Clinical Decision Algorithm

When considering megestrol acetate for appetite stimulation:

1. Screen for absolute contraindications

   • Hypersensitivity to megestrol acetate
   • Concurrent dofetilide use

2. Assess thromboembolic risk factors:

   • History of DVT/PE
   • Known thrombophilia
   • Active malignancy
   • Immobility
   • Recent surgery
   • Sickle cell disease
   • Patent foramen ovale

3. Evaluate cardiovascular status:

   • Existing edema
   • Heart failure
   • Hypertension

4. Check metabolic parameters:

   • Baseline glucose levels
   • Diabetes status

5. Consider alternative appetite stimulants if contraindications exist:

   • Dexamethasone (short-term use)
   • Olanzapine
   • Mirtazapine

Monitoring Requirements

If megestrol acetate is initiated despite relative contraindications:

• Regular monitoring for thromboembolic events
• Weight and edema assessment
• Blood glucose monitoring
• Cardiovascular assessment

Special Considerations

According to the ASCO guideline for cancer cachexia management, megestrol acetate may be offered as a short-term trial for patients experiencing appetite loss and/or weight loss, but the choice of agent and duration should depend on treatment goals and assessment of risk versus benefit 3. The significant risks associated with megestrol acetate, particularly thromboembolic events, should be carefully weighed against potential benefits in appetite stimulation and weight gain.