– U.S. Sen. Al Franken of Minnesota has added his voice to the congressional outcry against price increases Mylan pharmaceutical company made to its epinephrine auto-injector that treats potentially deadly allergic reactions.

Last week, Sen. Amy Klobuchar of Minnesota called for a Senate Judiciary Committee hearing and asked the Federal Trade Commission to investigate possible antitrust violations by Mylan, which raised the price of a two-pack of its EpiPen product from $100 in 2008 to $500 to $600 in 2016.

On Tuesday, Franken, Klobuchar and 18 other senators challenged Mylan's decision to maintain the price of its brand-name product while introducing a half-price "authorized generic" and increasing the value of company-issued discount coupons to be applied to the cost of EpiPens.

The company took that step Monday as it tries to quell growing outrage over the price increases. It has also increased the number of people eligible for a subsidy program designed to eliminate out-of-pocket costs for uninsured or underinsured consumers, moves the chief executive characterized as "an extraordinary public response."

But Tuesday's letter to CEO Heather Bresch, daughter of Sen. Joe Manchin, D-W.Va., questioned those strategies. The senators said the company's new generic might not be as readily available to consumers as a product from an independent competitor.

They called discount coupons a "complex shell game" to keep prices high and noted that subsidizing insurance co-payments still leaves insurance companies reimbursing Mylan for high prices that could eventually be passed along to consumers in the form of increased health insurance premiums.

The senators asked for specific details about the use of discount coupons, copay subsidies and the ways Mylan planned to inform consumers of the expanded programs. The letter also informed the company that it was illegal for Medicare and Medicaid patients to use the coupon and copay programs.

Finally, the letter asked for a specific explanation of Mylan's EpiPen4Schools initiative which provides four free auto-injectors per year to schools and replenishes the supply for free if any of those pens is used in a lifesaving situation.

The senators asked Bresch to explain if schools had to pay to enroll in the program and how many additional EpiPens schools had purchased from the company and at what price. In addition, Bresch was asked if Mylan prohibited EpiPen4Schools participants from buying any other brand of epinephrine auto-injector.