The FDA has approved over-the-counter (OTC) sale of the weight-loss drug orlistat (Xenical – Roche)1 as alli (GlaxoSmithKline), to be used in combination with a reduced-calorie, low-fat diet. Orlistat binds to gastric and pancreatic lipases, preventing absorption of about 30% of dietary fat with the 120-mg prescription dose, and 25% with the 60-mg OTC dose. A 16-week controlled trial of the OTC dose (60 mg 3 times daily with meals) in overweight, not obese, patients (average BMI 26.8) on a reduced-calorie, low-fat diet found that patients taking the drug lost 1.15 kg more than those taking placebo.2

Orlistat causes flatulence with oily spotting, loose stools, fecal urgency and occasional incontinence in 20-40% of patients on a low-fat diet; these effects presumably would be more frequent and more severe with a higher fat intake or self-prescription of higher-thanrecommended doses. The drug also interferes with absorption of fat-soluble vitamins (A, D, E, K); the manufacturer recommends that patients also take a multivitamin supplement at bedtime. Orlistat can increase the anticoagulant effect of warfarin and may interfere with the absorption of other drugs.

A “starter pack” of 90 capsules of alli (60 mg each) costs $62.99, compared to $224.64 for 90 capsules of Xenical (120 mg each).3

1. Orlistat for obesity. Med Lett Drugs Ther 1999; 41:55.

2. JW Anderson et al. Low-dose orlistat effects on body weight of mildly to moderately overweight individuals: a 16 week, double-blind, placebo-controlled trial. Ann Pharmacother 2006; 40:1717.

3. Cost based on information from drugstore.com (June 11, 2007).