What is the usual dosing of Megace (megestrol acetate)?

Megace (Megestrol Acetate) Usual Dosing

For cancer-related anorexia and cachexia, start with 800 mg daily of the oral suspension, which is the most commonly used and effective dose, though 160 mg daily is a reasonable initial dose in routine clinical practice to minimize cost and side effects. 1, 2

Standard Dosing Regimens by Indication

Cancer-Related Anorexia/Cachexia (Primary Use)

• Initial dose: 800 mg/day orally is the most widely studied and effective dose for appetite stimulation and weight gain 1, 3
• Alternative starting dose: 160 mg/day is reasonable for initial treatment in routine practice, balancing efficacy with cost and convenience 2
• Dose range: 160-1,280 mg/day with demonstrated positive dose-response effect for appetite stimulation 2
• Optimal therapeutic range: 480-800 mg/day appears to provide the best balance of efficacy and tolerability 4, 5
• The liquid formulation (oral suspension) is preferred over tablets due to better bioavailability and lower cost 4

AIDS-Related Anorexia/Cachexia

• FDA-approved dose: 625 mg/5mL oral suspension once daily (concentrated NanoCrystal Dispersion formulation) 6, 3
• Standard dose: 800 mg/day of the original oral suspension formulation 3

Oncologic Indications (Breast/Endometrial Cancer)

• Breast cancer: 160 mg/day (40 mg four times daily) 7
• Endometrial carcinoma: 40-320 mg/day in divided doses 7
• At least 2 months of continuous treatment is required to determine efficacy for cancer treatment 7

Dosing Considerations and Adjustments

Dose Titration Strategy

• Starting approach: Begin at 160 mg/day to assess tolerance, then increase to 480-800 mg/day based on response 1, 2
• High-dose regimen: Some protocols use 800 mg/day for 4 weeks, then reduce to 400 mg/day for maintenance 8
• Maximum studied dose: 1,280 mg/day, though doses above 480 mg/day show diminishing additional benefit 1, 2

Administration Tips

• For GI side effects: Divide the daily dose and take with meals (e.g., 400 mg twice daily with breakfast and dinner) 5
• Single daily dosing is acceptable and improves compliance, particularly with concentrated formulations 6, 3

Moderate Dose Alternative

• 400 mg/day has shown efficacy in dialysis patients with malnutrition, with fewer side effects than higher doses 9
• This moderate dose improved nutritional status, reduced inflammation, and was well-tolerated over 16 weeks 9

Critical Safety Warnings

Major Risks Requiring Monitoring

• Thromboembolic events: Patients are 1.84 times more likely to develop thrombophlebitis or pulmonary embolism compared to placebo 4
• Mortality risk: Relative risk of 1.42 compared to placebo, with 1 in 23 patients dying from treatment-related complications 4
• Edema: Occurs with relative risk of 1.36 4
• Regular assessment for thromboembolic phenomena is essential throughout therapy 4

Weight Gain Characteristics

• Weight gain is primarily adipose tissue (fat mass) rather than lean body mass or skeletal muscle 4, 5, 9
• This limits clinical benefit in cachexia where muscle preservation is desired 4
• Body fat proportion can increase by 31% and triceps skinfold by 40% 9

Expected Response Rates

• Appetite improvement: 1 in 4 patients (approximately 25%) 4
• Weight gain: Only 1 in 12 patients (approximately 8%) 4
• Complete response rate: 8% in advanced cancer patients 8

Duration of Therapy

• Minimum trial period: At least 2 months to determine efficacy 7
• Recommended approach: Limit duration to short-term trials rather than indefinite use due to cumulative risks 4
• Long-term monitoring: Assess adrenal function in patients on prolonged therapy 4

Alternative and Combination Strategies

When to Consider Alternatives

• Corticosteroids (e.g., dexamethasone): Provide similar appetite stimulation with different toxicity profile and lower cost 4
• Combination with olanzapine: One trial showed superior weight gain (85% vs 41%) when olanzapine was added to megestrol acetate 4
• Exercise programs: Should be combined with megestrol to maintain or increase lean body mass 4

Inferior Alternatives

• Cannabinoids (dronabinol): Less effective than megestrol acetate for appetite stimulation 4
• Cyproheptadine: Lacks sufficient evidence of benefit for cancer cachexia 4

Clinical Context for Use

Appropriate candidates: Patients with cancer-related anorexia/cachexia where increased appetite is an important quality of life goal 4

Key decision factors: Consider expected survival and comorbidities when choosing between megestrol acetate and corticosteroids 4