That year, the FDA raised concerns about adulterated drugs coming into the U.S. from two Indian factories owned by Ranbaxy and opened an investigation.

WSJ: Daiichi: Ranbaxy Shareholders Hid Information

Earlier this month, a U.S. subsidiary of Ranbaxy pleaded guilty to felony charges relating to adulterated drugs made at the two manufacturing facilities, according to the Justice Department.

WSJ: Daiichi: Ranbaxy Shareholders Hid Information

"We don't have any system in place for authenticating drugs in the U.S., " said Allan Coukell, director of medical programs at the Pew Health Group, who co-wrote a report last year on counterfeit and adulterated drugs.

WSJ: Fakes Infiltrate Injectable Drugs