“There is absolutely no reason to believe that trade policies designed to raise prescription drug prices overseas will result in equivalent or any decreases in prices in the United States,” six House Democrats, led by Representatives Jan Schakowsky of Illinois and Rosa DeLauro of Connecticut, said in a recent letter to Mr. Trump.

People who work in the industry said it was unlikely that consumers would go to the pharmacy counter and see a meaningful reduction in drug prices before the end of the year.

Mr. Trump is expected to criticize brand-name drug manufacturers for high list prices and maneuvers that delay the marketing of lower-cost generic drugs. He is also expected to go after middlemen known as pharmacy benefit managers, saying they profit from rebates paid by drug companies but do not share much of the savings with patients.

Dr. Peter B. Bach of Memorial Sloan Kettering Cancer Center in New York, an expert on drug prices, said: “Administration officials are talking about defects in the market that make some drugs unaffordable. The real question is whether the president will take on new brand-name drugs that have no competitors and cost hundreds of thousands of dollars a year.”

The United States can pressure foreign nations through diplomacy and trade negotiations. In its annual report card on the protection of intellectual property rights around the world, the United States trade representative last month criticized the drug pricing and reimbursement policies of Canada, South Korea, Japan, India, Turkey, New Zealand and a number of European Union countries, saying they did not adequately recognize the value of innovative medicines.

America’s trading partners must “contribute their fair share to the research and development of new cures and therapies,” the report said, echoing Mr. Trump’s contention that foreign price controls were “very unfair to this country.”

The report said the Trump administration had recently secured a commitment from South Korea to revise its drug pricing policy to provide higher payments for certain innovative American-made drugs. But the administration said it was concerned about the way Canada sets price ceilings for many prescription drugs. An independent quasi-judicial body reviews drug prices in Canada to make sure they are not excessive.