The committee is especially interested in how PBMs affect drug costs overall and the prices patients pay at the pharmacy counter and in their health insurance premiums in particular, according to a committee staffer. The requests came after the Federal Trade Commission launched an investigation into PBM practices and several state governments began probes. The issue of high drug prices is a popular concern and a rare source of agreement among Republican and Democratic lawmakers, as well as a potential area for joint legislation.

The companies say their work saves money for health insurers, employers and patients. But they have drawn criticism, especially from pharmaceutical companies, that their push for discounts and other business practices actually has the opposite effect of increasing drug prices. A pharmacy industry representative countered with a 2019 report from the Government Accountability Office that says PBMs won billions in savings for certain Medicare plans and kept less than 1% of the rebates they negotiated in 2016.

"Pharmacy-benefit companies have a proven track record of reducing prescription drug costs," says J.C. Scott, president of the Pharmaceutical Care Management Association. "In the Medicare prescription drug program, the work pharmacy benefit companies do to push big drug companies for cost concessions is the primary force in keeping monthly premiums affordable."

In addition to seeking records about rebates and fees from PBMs, the committee asked the companies for documents related to their relationships with Zinc Health Services, Ascent Health Solutions and Emisar Pharma Services, three group purchasing organizations that the PBMs formed to help negotiate rebates. The committee expects to produce a report recommending potential legislation, the committee staffer says.

Related: PBM satisfaction among health plans and employers has dropped to a three-year low, study finds

"The House Oversight and Accountability Committee is shining a light on this issue in the health care system and will continue to examine solutions to make prescription drugs more affordable for all Americans," Comer says.