What is the recommended dosage and usage of orlistat (Xenical) for weight loss?

Recommended Dosage and Usage of Orlistat (Xenical) for Weight Loss

Orlistat is available in 60-mg (over-the-counter) or 120-mg (prescription) capsules, with the recommended dosage being one capsule taken during or within 1 hour after each main meal containing fat, not exceeding three capsules daily, as an adjunct to a reduced-calorie, low-fat diet and physical activity program. 1, 2, 3

Dosage Recommendations

• Prescription strength (Xenical): 120 mg three times daily with meals containing fat
• Over-the-counter strength (Alli): 60 mg three times daily with meals containing fat
• Doses can be omitted if a meal contains no fat or is skipped 1, 2
• The 60 mg dose has approximately 85% of the efficacy of the 120 mg dose for weight loss 4

Administration Guidelines

• Take orlistat during or within 1 hour after meals containing fat 1, 2, 3
• Skip dose if meal contains very little or no fat 1, 2
• Must be combined with a reduced-calorie, low-fat diet (≤30% of calories from fat) 1, 2, 3
• Take a daily multivitamin containing fat-soluble vitamins (A, D, E, K) at bedtime or at least 2 hours apart from orlistat doses 1, 2

Expected Outcomes

• Most weight loss occurs within the first 6 months of treatment 1, 3
• Clinical trials show an average weight loss of 2.81 kg more than placebo 1
• Approximately 53% of patients achieve 5% total body weight loss and 26% achieve 10% total body weight loss 2
• If 5% weight loss is not achieved after 12 weeks, consideration should be given to discontinuing orlistat 2

Side Effects Management

Common Gastrointestinal Side Effects

• Oily spotting/stool, fecal urgency, flatulence with discharge, fecal incontinence 1, 2
• These side effects typically occur early in treatment (within first 4 weeks) 2
• Usually mild to moderate in intensity and often resolve despite continued treatment 2
• Approximately 4% of patients discontinue orlistat due to these GI complaints 2

Managing Side Effects

• Strictly adhere to a low-fat diet (≤30% of calories from fat) to minimize GI side effects 2
• Add fiber supplements to help manage gastrointestinal symptoms 2
• Side effects are less common with the 60 mg dose compared to the 120 mg dose 4

Important Precautions

Drug Interactions

• Take lipophilic medications (cyclosporine, levothyroxine, warfarin) at least 2 hours before or after orlistat 1, 2
• Monitor drug levels when appropriate, particularly for medications with narrow therapeutic windows 2

Contraindications

• Pregnancy or breastfeeding
• Chronic malabsorption syndrome
• Cholestasis
• Cholelithiasis (gallstones)
• Concurrent use of cyclosporine, warfarin, or antiepileptic drugs without appropriate monitoring 2

Monitoring Requirements

• Regular assessment of gastrointestinal symptoms
• Periodic liver function monitoring (FDA warning about potential serious liver injury) 2
• Evaluation of fat-soluble vitamin levels for extended treatment 2

Clinical Considerations

• The American Gastroenterological Association has made a conditional recommendation against routine use of orlistat due to modest weight loss benefits and significant gastrointestinal side effects 1
• However, patients who place higher value on modest weight loss and lower value on GI side effects may reasonably choose orlistat 1
• Orlistat is indicated for adults with BMI ≥30 kg/m² or BMI ≥28 kg/m² with weight-related comorbidities 2, 3