Measures laid out in letters to 17 companies would either have modest impact or face legal challenges, say industry experts.

President Donald Trump surprised pharma CEOs on Thursday with letters demanding they acquiesce to his most-favored drug-pricing scheme (see what we did there?) by the end of September, setting up a late-summer lobbying fight for the industry.

President Donald Trump sent letters to the leaders of 17 major pharmaceutical companies outlining how they should slash U.S. prescription drug prices to match those paid overseas, the White House said on Thursday.