Adults with a body mass index (BMI=kg/m²) of 25-<30 are considered overweight; those with a BMI of ≥30 are considered obese.

The results of a postmarketing study of its cardiovascular safety have led to the removal of the weightloss drug sibutramine (Meridia) from the market in the US and Canada. It has also been withdrawn in Europe and Australia, but remains on the market in many other countries. The study that led the FDA to ask Abbott Laboratories to withdraw the drug randomized 10,744 overweight patients with cardiovascular disease, diabetes or both to sibutramine or placebo for a mean duration of 3.4 years. The primary endpoint (non-fatal myocardial infarction, nonfatal stroke, cardiovascular death or resuscitation after cardiac arrest) occurred in 561 of 4906 patients (11.4%) taking sibutramine and in 490 of 4898 (10%) taking placebo (p = 0.02). Death from any cause occurred in 8.5% of the patients who took sibutramine and in 8.2% of those on placebo; this difference was not statistically significant.1

1. WP James et al. Effect of sibutramine on cardiovascular outcomes in overweight and obese subjects. N Engl J Med 2010; 363:905.

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Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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Losing even a small amount of weight and increasing physical activity can prevent some of the complications of obesity, particularly type 2 diabetes. Diet and exercise are the preferred methods for losing weight but are associated with high long-term failure rates. Drugs may help some patients, but all currently available drugs for weight reduction have drawbacks. Gastric surgery can produce marked weight loss in the severely obese, but long-term data on safety are limited.

At a US Senate hearing prompted by the withdrawal of Vioxx, an FDA officer cited 5 drugs as potentially dangerous. It may be useful to revisit Medical Letter reviews of these drugs.

The latest definitions of overweight and obesity are based on body mass index (BMI). The BMI is calculated by dividing the weight in kilograms by the square of the height in meters (kg/m²). More than half of American adults are considered overweight with a BMI of ≥25, and about one third are obese with a BMI of ≥30. All ages seem to be affected; the proportion of children and adolescents who are overweight has more than doubled in the past 25 years. There is no lack of effort to treat obesity: drugs, diets and programs to change lifestyle are the basis for a large and flourishing industry. The frequent failure of diet and drug treatment sometimes leads to recommendations for surgery, usually restricted to those with a BMI ≥40.

Orlistat, a lipase inhibitor that decreases absorption of fat from the gastrointestinal tract, is now available for treatment of obesity.

Sibutramine hydrochlorid monohydreate (Meridia - Knoll), which is structurally related to amphetamine, has been approved by the FDA for treatment of obesity. It is classified by the Drug Enforcement Agency (DEA) as a schedule IV controlled substance.