But the liver damage risks were too noticeable for the advisory panel. The FDA says that drug-induced liver injury is the top cause of acute liver failure, a rare disease that can produce critical illness in a few days, cause death, or necessitate a liver transplant. It's the leading reason why drugs are removed from the market and why the FDA requires restricted use of certain drugs and special monitoring of patients. Depending on Exanta's performance, Merck ( MRK) could receive a royalty of as much as 20% of sales. That's the result of a 1994 joint venture between Merck and the then-independent Astra. The joint venture was restructured into a partnership in 1998, and the partnership was restructured after Astra merged with Britain's Zeneca in 1999. Right now, it appears Exanta won't be producing much revenue for either company.