What is the recommended dosage and usage of Orlistat (Xenical) for weight loss in obese or overweight individuals?

Orlistat Dosage and Usage for Weight Loss

The recommended dosage of orlistat (Xenical) for weight loss is 120 mg taken three times daily with each main meal containing fat, in conjunction with a reduced-calorie, low-fat diet. 1

Dosage Details

• Prescription strength (Xenical): 120 mg capsule taken three times daily with meals
• Over-the-counter strength (Alli): 60 mg capsule taken three times daily with meals
• Timing: Take during or within 1 hour after meals containing fat
• Skip dose if meal contains no fat or if meal is skipped
• Do not exceed 3 capsules daily

Patient Selection

Orlistat is appropriate for:

• Adults aged 18 years and older
• BMI ≥30 kg/m² (obese) or
• BMI ≥28 kg/m² (overweight) with weight-related comorbidities 1, 2

Dietary Recommendations

When taking orlistat:

• Follow a reduced-calorie diet with approximately 30% of calories from fat
• Distribute fat intake evenly across three main meals
• Higher fat meals may increase gastrointestinal side effects
• Take a daily multivitamin containing fat-soluble vitamins (A, D, E, K) at bedtime or at least 2 hours apart from orlistat 1

Expected Outcomes

• Most weight loss occurs in the first 6 months of treatment
• Clinical trials showed weight loss of 2.81 kg more than placebo
• Approximately 53% of patients achieve 5% total body weight loss
• Approximately 26% achieve 10% total body weight loss 1

Monitoring and Follow-up

• If 5% weight loss is not achieved after 12 weeks, consider discontinuing
• Monitor for gastrointestinal side effects
• Monitor fat-soluble vitamin levels if treatment extends beyond 1 year
• Monitor liver function periodically (FDA warning for potential liver injury) 1

Important Precautions and Contraindications

Orlistat should not be used in:

• Pregnancy or breastfeeding
• Chronic malabsorption syndrome
• Cholestasis
• Patients with cholelithiasis (gallstones) 3
• Concurrent use of cyclosporine, warfarin, or antiepileptic drugs 1

Common Side Effects

The most common side effects are gastrointestinal and related to the mechanism of action:

• Oily spotting/stool
• Fecal urgency
• Flatulence with discharge
• Fecal incontinence
• Increased defecation 1

Important Clinical Considerations

1. FDA Warning: The FDA has added a label warning about potential serious liver injury with orlistat use 1

2. Medication Interactions: Take orlistat at least 2 hours before or after medications that may interact with it, particularly fat-soluble medications 1

3. Efficacy Limitations: The American Gastroenterological Association suggests against routine use of orlistat due to modest weight loss benefits (2.78% total body weight loss) compared to placebo and significant gastrointestinal side effects 1

4. Patient Selection: Patients who place high value on potential small weight loss and low value on GI adverse effects may reasonably choose treatment with orlistat despite the conditional recommendation against its use 1

5. Duration: While studied for periods of 1-2 years, most weight loss occurs in the first 6 months 2, 4

By following these dosage and usage guidelines, patients can maximize the potential benefits of orlistat while minimizing adverse effects. However, it's important to remember that diet and exercise remain the foundation of any weight loss program, with orlistat serving as an adjunctive therapy.