One thing the bill does is rein in drug price increases in Medicare Part D, with increases limited to the pace of inflation; overages would have to be paid back to Medicare as inflation rebates. In addition, Medicare beneficiaries would also see their out-of-pocket costs capped, at $3,100—and that would start in 2022.

There would also be a provision requiring manufacturers of some single-dose container or package drugs refund Medicare Part B for discards; that by itself would save an additional $9 billion, and another $3.4 billion would be saved by redesigning Part D.

Beneficiaries would save money under the bill as well.

Some Senate Republicans have opposed the bill, viewing it as price controls, and Senate Majority Leader Mitch McConnell has said he probably wouldn't bring it up for a vote without substantial changes. And of course there's opposition to it from America's Health Insurance Plans and Pharmaceutical Research and Manufacturers of America.

Another proposal competing with the PDPA, advanced by House Speaker Nancy Pelosi, would require the federal government and the pharmaceutical industry to directly negotiate prices. The CBO estimated that plan would slash Medicare drug spending by $369 billion over the coming decade.

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• Majority of Americans support current efforts to bring down drug prices
• Is killing drug rebates really the answer to high drug prices?