(Reuters) — Three drugmakers will pay $122.6 million to resolve claims they used charities that help cover Medicare patients' out-of-pocket drug costs as a way to pay kickbacks aimed at encouraging the use of their medications, including some expensive ones.

The U.S. Justice Department on Thursday said Jazz Pharmaceuticals PLC, H. Lundbeck A/S and Alexion Pharmaceuticals Inc. had become the latest companies to settle claims stemming from an industrywide probe of drugmakers' financial support of patient assistance charities.

The government has alleged in earlier settlements that drugmakers used such charities as a means to improperly pay the copay obligations of Medicare patients using their drugs in violation of the Anti-Kickback Statute.

The investigation came amid growing attention to skyrocketing U.S. drug prices. Copays are meant to serve in part as a check on health care expenses by exposing patients to some of a drug's cost and make them price-sensitive.

The department said Jazz will pay $57 million, Lundbeck will pay $52.6 million and Alexion will pay $13 million.

None of the companies admitted wrongdoing. They did not immediately respond to requests for comment.

Drug companies are prohibited from subsidizing copayments for patients enrolled in the Medicare government healthcare program for the elderly. Companies may donate to nonprofits providing copay assistance as long as they are independent.

An investigation led by the U.S. Attorney's Office in Boston has prompted allegations some drugmakers and charities did not act independently enough.

The government alleged Alexion in 2010 asked a foundation to set up a fund that could help patients afford Soliris, a treatment for two rare blood disorders that costs over $500,000 annually, making it one of the most expensive drugs in the country.

While such funds are typically set up to allow patients to get help to afford treatments for a given diagnosis, the government said Alexion discussed with the foundation wanting to only support patients using Soliris.

The department said Jazz similarly asked a foundation to set up funds to cover copays for patients using its narcolepsy treatment Xyrem and its pain medication Prialt.

The foundation's funds through 2014 almost exclusively assisted patients using those two drugs and referred those with chronic pain trying to afford drugs other than Prialt elsewhere, the government said.

The department said Lundbeck beginning in 2011 donated millions of dollars to a charity's fund that ostensibly covered copays of patients with Huntington's Disease but in reality only covered the copays of patients using its drug Xenazine.