Mr. Trump plans to speak in the Rose Garden of the White House to an audience that includes members of Congress and patients who have suffered because of high drug costs.

The theme of the president’s initiative is “American patients first,” and his plan takes aim at what the White House calls “foreign freeloading.” The administration will, as expected, put pressure on foreign countries to relax drug price controls, in the belief that pharmaceutical companies can then lower prices in the United States.

“Other countries use socialized health care to command unfairly low prices from U.S. drugmakers,” said a summary provided by the White House on Thursday. “This places the burden of financing drug development largely on American patients and taxpayers, subsidizes foreign consumers, and reduces innovation and the development of new treatments.”

The United States spends well over $300 billion a year on prescription drugs sold at pharmacies and other retail outlets, and Medicare and Medicaid account for nearly 40 percent of that spending, according to the Department of Health and Human Services.

Mr. Trump plans to criticize brand-name drug manufacturers for setting high list prices and for trying to stifle competition by delaying the marketing of lower-cost generic drugs. He is also expected to criticize pharmacy benefit managers, saying they profit from rebates paid by drug companies but do not pass on much of the savings to patients.

Mr. Trump has repeatedly said that drug companies are “getting away with murder.”

In his State of the Union address in January, he said that “fixing the injustice of high drug prices” was one of his top priorities for 2018. “And prices will come down substantially,” he said. “Watch.”

As a presidential candidate, Mr. Trump supported two ideas that are anathema to the pharmaceutical industry: allowing Medicare officials to negotiate prices and allowing consumers to import prescription drugs from Canada and certain other countries where brand-name drug prices are generally lower than in the United States.