Congress is poised to make the biggest changes to Medicare in nearly two decades.

The Democrats’ health care and climate package, which the House is expected to take up on Friday after the Senate passed it on Sunday, aims to lower drug prices in Medicare, which would save both senior citizens and the federal government money.

The bill would allow Medicare to negotiate the price of certain prescription drugs for the first time and would limit the growth of drug costs. And it would cap how much Medicare enrollees have to pay for certain medications, including insulin.

The effort, however, is much narrower