From Monthly Prescribing Reference:
The FDA has notified healthcare professionals and consumers that it is reviewing new safety information regarding reports of liver-related adverse events in patients taking orlistat, which is marketed in the U.S. as Xenical (from Roche) and Alli (from GlaxoSmithKline). The FDA has received 32 reports of serious liver injury, including 6 cases of liver failure, in patients using orlistat.
The FDA is not advising doctors to stop prescribing orlistat at this time. The Wall Street Journal included a quote from Alli’s manufacturer:
There is no evidence that Alli causes liver damage, said Glaxo spokeswoman Deborah G. Bolding. She said the drug is minimally absorbed in the blood and works in the gastro-intestinal tract, meaning there is “no obvious biological mechanism” to suggest liver damage can occur with Alli.
I’m not sure if this was due to Bolding’s wording or the reporter’s, but the impression I got from the WSJ is that Xenical may be problematic—but Alli isn’t. But both are orlistat, and to be frank, if it was an obvious problem it would probably have been found long before now.
The FDA’s statement is here.