Anti-obesity drugs provide only modest weight loss
Despite being touted in the marketplace as miracle pills that can melt away pounds, doctors say that in reality the medications are no panacea to society's growing obesity epidemic and should only be taken by certain people.
"I think the most important thing that people need to understand is these are definitely not magic pills," said Dr. Raj Padwal, an assistant professor of internal medicine at the University of Alberta and principal author of the review.
Padwal and his colleagues looked at the results of 30 clinical trials of three drugs recommended for obese patients for long-term use - orlistat, sibutramine and rimonabant - and found that they helped people shed on average less than 11 pounds.
"We found that the amount of weight loss on average with these medications ranges between three and five kilograms," Padwal, who specializes in treating hypertension and obesity, said from Edmonton.
Orlistat (Xenical) reduced patients' weight by 6.4 pounds, sibutramine (Meridia) by about nine pounds and rimonabant (Acomplia) by just over 10 pounds in the studies, which each lasted at least a year. Participants had a mean weight of 220 pounds, with a body mass index (BMI) of 35. A BMI of 25 is considered normal.
In their analysis published in Friday's issue of the British Medical Journal, the researchers showed that those given one of the drugs were significantly more likely to achieve the minimum weight loss target of five to 10 per cent than those given a dummy pill.
But although the drugs overall can be beneficial in reducing risk factors for cardiovascular disease and diabetes, they have differing side-effects that in some cases can be detrimental, Padwal pointed out.
For some people, sibutramine can significantly boost blood pressure; rimonabant - which is commonly prescribed in the U.K. and some European countries but not approved in Canada or the United States - can elevate the risk of mood disorders such as depression.
In fact, a review of studies published Friday in The Lancet shows that obese patients taking rimonabant have a 40 per cent increased risk of developing severe depression and anxiety compared to those taking a placebo. Participants were up to three times more likely to stop taking the drug because of those mood disorders.
Padwal said getting patients to stick with any of the three weight-loss drugs long-term is a challenge.
"There's a large disconnect between what patients want in terms of weight loss and what practitioners desire," he said. "So patients will often want to lose . . . about 30 to 40 per cent of their initial weight. They want to get down to the weight they were in high school, two to three decades earlier."
"And they're disappointed when they're told that's going to be difficult to achieve."
Cost is also a major factor: orlistat and sibutramine (the only ones approved in Canada) will set back patients $80 to $130 per month, he said, noting that the drugs along with rimonabant represent more than $1 billion in worldwide sales for their makers each year.
