Enlarge / WASHINGTON, DC – SEPTEMBER 21: Mylan Inc. CEO Heather Bresch holds up a 2-pack of EpiPen as she testifies during a hearing before the House Oversight and Government Reform Committee September 21, 2016 on Capitol Hill in Washington, DC. The committee held a hearing on “Reviewing the Rising Price of EpiPens.” (Photo by Alex Wong/Getty Images) (credit: Getty | Alex Wong)

Over the nine or so years that Mylan, Inc. has been selling—and hiking the price—of EpiPens, the drug company has been misclassifying the life-saving device and stiffing Medicaid out of full rebate payments, federal regulators told Ars.

Under the Medicaid Drug Rebate Program, drug manufacturers, such as Mylan, can get their products covered by Medicaid if they agree to offer rebates to the government to offset costs. With a brand-name drug such as the EpiPen, which currently has no generic versions and has patent protection, Mylan was supposed to classify the drug as a “single source,” or brand name drug. That would mean Mylan is required to offer Medicaid a rebate of 23.1 percent of the costs, plus an “inflation rebate” any time that Mylan raises the price of the brand name drug at a rate higher than inflation.

Mylan has opted for such price increased—a lot. Since Mylan bought the rights to EpiPen in 2007, it has raised the price on 15 separate occasions, bringing the current list price to $608 for a two-pack up from about $50 a pen in 2007.That’s an increase of more than 500 percent, which easily beats inflation.