When a generic drug doesn't do much to lower costs for patients

• The impact on MS drugs' prices after the generic was introduced was minimal, and Copaxone's price increased immediately.

The bottom line: "We've been, really been, looking to generics for some price relief, and we're probably not going to get it as quickly as we want," Stacie Dusetzina, a health policy professor at Vanderbilt University, told NPR.

Go deeper:

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• California's bold new drug pricing plan