A bill U.S. Senator Tina Smith is introducing would block big pharmaceutical companies from extending their patents after making only minor changes to a drug:

“Might be for example just adding salt to the formulation and then that allows them to extend their patent, their market exclusive for five years.”

Smith says when a patent is extended it blocks the generic drug companies from producing a cheaper version of the drug:

“They’re basically buying a monopoly by buying time.”

Democrat Smith is introducing the legislation with Republican Senator Pat Roberts of Kansas.