Health Canada has approved Roche Canada's Xenical (orlisat), the only prescription anti-obesity medication that blocks the absorption of dietary fat, one of the commonly accepted causes of obesity.

Xenical, unlike other anti-obesity medications that work in the brain or nervous system to suppress appetite, is a safe non-systemically acting medication that works specifically in the digestive tract to prevent the absorption of approximately 30 per cent of dietary fat. The non-digested fat is excreted by the body.

The fat-blocking action of Xenical not only helps patients decrease weight and keep it off, it has also been shown to improve obesity-related conditions including high cholesterol, diabetes (insulin and blood sugar) and high blood pressure.

On pharmacy shelves today

Xenical is indicated for weight loss and weight maintenance when used in conjunction with a modest calorie-reduced diet. It will be prescribed to overweight and obese patients with a body mass index (BMI) of greater than or equal to 30 or greater than or equal to 27 in the presence of other risk factors. Current research indicates that 30 per cent of the Canadian adult population is obese (BMI greater than or equal to 27).

Xenical is the most comprehensively studied anti-obesity medication ever, with more than 7,000 patients world-wide having participated in clinical studies. (Currently, Xenical is available in 19 countries around the world.) There are currently two studies ongoing in Canada. It also has the only published reports of continuous double-blind treatment for two years in clinical studies. These studies have proven weight loss and, more importantly, maintenance of lost weight for up to two years, as well as the efficacy of Xenical in patients with type II diabetes. Obesity is known to be a significant cause of type II diabetes and the incidence of this disease rises with an increasing severity of obesity and weight gain.

Pooled data from clinical trials show that three times as many patients taking Xenical in combination with a mild calorie-reduced diet lost more than 10 per cent of their initial body weight versus diet alone. Two times as many patients lost more than five per cent of their initial body weight compared to diet alone. Weight loss is seen within two weeks of initiating therapy.

In the most recently published study on Xenical in the Journal of the American Medical Association, patients lost on average 19.5 pounds (8.76 kilos) in the first year versus 12.8 pounds (5.81 kilos) on placebo. In the second year, when calorie intake was increased and the goal was to maintain lost weight, those patients on placebo regained 63 per cent of their lost weight, versus only a 35 per cent regain for those on Xenical. The authors noted, however, that 34 per cent of patients on Xenical for the full two years maintained a weight loss of more than 10 per cent of initial body weight compared with only 17.5 per cent who received placebo for the full two years.

"Xenical-treated patients typically lose at least five to 10 per cent of body weight over the first year of treatment," said Dr. Lawrence Leiter, a professor of medicine at the University of Toronto, director of the Lipid Clinic at St. Michael's Hospital in Toronto and a clinical investigator in Xenical clinical trials. "We know that weight loss in this range has a positive impact on obesity-related risk factors such as high blood pressure, type II diabetes and cholesterol abnormalities.

"What's encouraging is that clinical trials with Xenical have demonstrated this benefit. This is consistent with the emphasis on weight loss as a way to achieve improved health outcomes."

Patients treated with Xenical have shown measurable improvements in total and low-density lipoproteins (LDL) or bad cholesterol, systolic and diastolic blood pressure, concentrations of fasting glucose (blood sugar) and insulin.

In a study published last year, 43.2 per cent of Xenical-treated patients with type II diabetes reduced the amount of diabetes medication they required versus only 28.9 per cent in the non-treatment group and 11.7 per cent of the Xenical-treated group completely discontinued their use of diabetes medication.

Xenical is a blue, 120 mg capsule that is taken three times daily with meals. A patient's total daily food intake will vary based on gender and current weight, but could be around 1,800 to 2,700 calories a day or higher -- significantly more than fad diets which often contain 1,200 or less calories a day. Meals eaten with Xenical can contain up to 30 per cent of calories from fat, consistent with Health Canada's nutrition recommendations when Canada's Food Guide to Healthy Eating is followed.