Senator Bernie Sanders of Vermont frequently assails the cost of prescription drugs, citing the statistic that one in five Americans cannot afford them. He has called for prices to be cut in half.

By 2015, annual spending on prescription drugs in the United States reached about $1,000 per person, accounting for 16.7 percent of overall personal health care spending.

America spends much more on prescription drugs than comparable wealthy nations.

A Kaiser Health poll from earlier this year found that 24 percent of Americans said it was “somewhat difficult” or “very difficult” to afford their prescription drugs.

Mr. Sanders argues that drug manufacturers — along with Wall Street, the fossil fuel industry and the health care industry — exhibit the kind of “corporate greed” his campaign wants to take on.

By comparing the profits of big pharma with Americans’ struggle to pay for their products, Mr. Sanders can argue that “unfettered capitalism” benefits the rich and hurts ordinary Americans.