Description
Xenical (orlistat)
Xenical contains orlistat 120 mg and is used for weight management in adults with a BMI of 30 or above, or from 28 upwards when additional risk factors like hypertension or type 2 diabetes are present. It works entirely locally in the gastrointestinal tract — it inhibits pancreatic and gastric lipases, preventing the breakdown and absorption of a portion of dietary fat. At the 120 mg dose taken three times daily, approximately 30% of dietary fat intake passes through unabsorbed rather than entering circulation.
Orlistat is not an appetite suppressant, doesn’t affect the central nervous system, and has no systemic pharmacological activity beyond the gut. What it does, it does in the intestine.
Dosing
One 120 mg capsule taken with each main meal containing fat — three times daily, maximum 360 mg/day. Taken just before, during, or up to one hour after a meal. If a meal is skipped or contains no fat, the dose is also skipped. Orlistat is part of a reduced-calorie diet and increased physical activity program, not a standalone treatment. If 5% of baseline body weight has not been lost after 12 weeks of treatment, continuing the drug is unlikely to produce meaningful benefit.
Fat-soluble vitamins
Unabsorbed fat also carries fat-soluble vitamins through the intestine. Orlistat reduces absorption of vitamins A, D, E, and K. A daily multivitamin containing fat-soluble vitamins should be taken at least 2 hours before or after each orlistat dose. This is not optional — vitamin deficiency is a real consequence of untreated malabsorption over months of treatment.
Drug interactions
Cyclosporine absorption is significantly reduced by orlistat — take cyclosporine at least 3 hours before or after orlistat, and monitor levels. Orlistat reduces levothyroxine absorption; thyroid function monitoring is needed when these are co-administered. Anticoagulant therapy with warfarin or similar drugs requires INR monitoring during orlistat treatment, as altered fat-soluble vitamin K absorption affects anticoagulation.
Side effects
Oily or fatty stools, fecal urgency, oily spotting, increased bowel movements, and flatulence are the defining side effects — all are direct consequences of unabsorbed fat in the intestine. Their severity is closely related to fat content of meals: high-fat meals produce significantly more GI effects. Fecal incontinence occurs in some patients. Blood sugar can drop in diabetic patients as caloric absorption decreases.
Rare post-marketing reports of hepatic injury have been received, though a causal relationship was not established. Monitoring liver function is prudent in patients who develop nausea, jaundice, or right upper quadrant pain.