California Attorney General Jerry Brown and the Federal Trade Commission are suing four pharmaceutical companies they say conspired to keep generic versions of testosterone from being sold.
Brown says the conspiracy cost consumers millions of dollars. He filed suit Monday in U.S. District Court in Los Angeles.
Solvay and three other drug manufacturers allegedly agreed not to make generic alternatives to Solvay's testosterone supplement, AndroGel, in exchange for millions of dollars in payments.
Supplements such as AndroGel are used to prevent muscle loss, fatigue or erectile dysfunction in critically ill patients.
Generic alternatives typically push down the price of brand name drugs by 50 to 80 percent. AndroGel's annual sales were more than $400 million in 2007.
Solvay spokeswoman Jessica Riley did not immediately return a phone message left Monday.