According to the consumer watchdog Public Citizen, the weight loss drugs Alli and Xenical should be removed from the market because of the growing risk of side effects that include liver damage, pancreatitis and kidney stones.
At present this is the only FDA-approved class of weight-loss drugs. The Public Citizen issued a petition to the U.S. Food and Drug Administration Thursday – its second in five years - calling for the agency to ban the class of drugs called orlistat, better known by the prescription brand names Xenical and Alli.
In a review in Ontario, Canada over a seven-year period it was noted that orlistat causes a 2% increase in acute kidney injuries within one year of patients starting the drug. The findings were reported by Dr Matthew Weir (University of Western Ontario, London) and colleagues in a research letter published April 12, 2011 in the Archives of Internal Medicine.
Among 953 new orlistat patients identified between January 2002 and March 2008, five patients experienced an acute kidney injury event in the 12 months prior to starting on the diet drug. By contrast, 18 patients experienced an event within 12 months after filling their prescription. As a “test of specificity,” Weir et al also tracked upper-gastrointestinal bleeding in the same fashion (“since there is no plausible reason why orlistat would be associated with this outcome”) and found no differences in rates of upper-GI bleeds before and after orlistat prescription.
Weir and colleagues believe their analysis addresses “an important safety issue,” although they cannot prove that the kidney injuries were a direct result of orlistat prescription. Despite several limitations of their analysis, they conclude: “In the appropriate setting, physicians should consider orlistat as a potential cause of acute kidney injury.”
Dr. Sidney Wolfe, director of Public Citizen's Health Research Group said, “These drugs have the potential to cause significant damage to multiple critical organs, yet they provide meager benefits in reducing weight loss in obese and overweight patients.” An estimated 40 million people worldwide have taken either Xenical or Alli in the last decade. But sales have decreased substantially over the last decade. Alli sales dropped from $145 million in 2007 to $84 million by mid-2010, according to a report released by Public Citizen. The drugs' maker, GlaxoSmithKline, announced Thursday it is trying to sell the brands.
Studies suggest that taking Xenical or Alli would only help people lose 4 to 6 pounds more than they would with only diet and exercise. “The benefit was never that great, but many people thought they'd take their chances,” said Wolfe. The drugs work by blocking absorption of about a third of fat enzymes that enter the body. Instead, the fat passes through the body to the gastrointestinal tract until it is excreted. These medications also block fat-soluble vitamins including vitamins A, B, and K. Some of the more common side effects of Alli or Xenical include diarrhea and stool leakage.
According to Dr. Donald Hensrud, associate professor of nutrition and preventive medicine at the Mayo Clinic in Rochester, Minn., the longer a patient stays on the medication, the more likely these symptoms will go away. “The chances of having those side effects are a bit overrated,” said Hensrud. “Only about 20 percent of people get those side effects, and in most people it lasts for less than a week.”
However there exists concerns of damage to other organs like liver, pancreas and kidney. The FDA received 47 reports of acute pancreatitis and 73 cases of kidney stones attributed to orlistats. While many experts say these side effects are rare, it's not clear what segment of people who use the drug may experience these severe conditions.
GlaxoSmithKline offered a statement saying, “GSK is committed to ensuring that consumers and physicians understand the safety profile of orlistat and alli. GSK continues to proactively monitor for the safety of orlistat and share all relevant information with regulatory agencies.”
In fact, those who are overweight are already at a higher risk for liver disease, Hensrud said. “So it might not be the medication,” he said. “It might just be the people who would probably take these medications would already experience these effects. The data is not consistent.”
The FDA rejected Public Citizen's first petition in April 2006, which cited a preliminary study in rats that suggested orlistat caused pre-cancerous lesions in the colon. It's unclear whether the FDA will accept Public Citizen's new petition. “It seems like Alli is going to wither away on its own anyway. Its market has already decreased considerably,” said Keith Ayoob, a registered dietician and director of the nutrition clinic at the Rose R. Kennedy Center at the Albert Einstein College of Medicine. “It wouldn't surprise me if the FDA allowed it to continue with restriction without pulling it.”
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