President Donald Trumps declaration Monday that the Department of Health and Human Services will pursue a plan to equalize drug prices with other countries both seeks to fulfill a campaign promise and fits with the America first theme of his second term.The path forward is uncertain, however. At the end of Trumps first term, his administration had proposed a plan to temporarily apply so-called most-favored nation pricing controls on a limited number of drugs in Medicare, which was rejected by the courts on procedural grounds.In the new plan, as sketched out by administration officials and in an executive order, most-favored nation prices would be applied broadly to drugs in both government programs and commercial markets.Mondays announcement left many questions unanswered, not the least of which being the legal authority to impose price controls in the private sector. Trump also hinted he might try to persuade Congress to include his most-favored nation plan in a major tax and budget bill expected to move this year although published reports suggested its already been rejected by congressional leaders.What does the order accomplish?The order seeks to show that Trump, whose record on fulfilling healthcare promises is spotty, is still working to help lower costs. Moreover, he aims to prove he can do better than former President Joe Biden, who in signing the Inflation Reduction Act implemented limited Medicare drug cost controls that have survived court challenges and will take effect in 2026 if not repealed by Congress.The order could also be a bargaining chip in trade and tariff negotiations. In his comments, Trump portrayed other countries as freeloaders on U.S. consumers and investment. He has asked the Commerce Department and U.S. Trade Representative to explore whether the low prices in other countries constituted unfair trading practices.Would patients see prices reduced by as much as Trump promised?In a social media post, Trump promised prices would drop almost immediately, by 30% to 80%. Thats a simplification that assumes prices will immediately fall to those charged in other countries who are members of the Organization for Economic Co-operation and Development.According to the policy think tank Rand, gross manufacturer prices there are about 36% of those in the U.S. However, that figure doesnt account for the rebates and discounts drugmakers offer insurers in the U.S., which, depending on the type of drug, can substantially lower the net price.If the U.S. were to impose a most-favored nation plan, drugmakers would need to make up their revenue elsewhere, which might result in a gradual increase in the reference prices used to establish the U.S. price. The practice of confidential rebates in other countries could also potentially skew the publicly disclosed price upward in those countries and, with them, the corresponding U.S. charges.Moreover, drugmakers could choose to stop marketing high-cost drugs in certain countries where the price is lowest to prevent them from being used in most-favored nation calculations.Will this be challenged in the courts?Almost certainly. The administration has little authority under the law to impose price controls on the private sector, and what authority it has to do so in Medicare was established through passage of the IRA.This could explain the construct of the executive order, which first establishes a direct-to-consumer mechanism for drugmakers to sell medicines at the most-favored nation prices and kicks off a negotiation and regulatory process to deliver the products at those prices.Some Wall Street analysts are predicting price reductions will be achieved through limited voluntary industry action and a limited scope demonstration project for Medicare and Medicaid enrollees, which could dodge the likely legal action.How is pharma responding?The Pharmaceutical Research and Manufacturers of America, an industry trade group, called the proposal a bad deal for American patients and workers. John Crowley, CEO of the Biotechnology Innovation Organization, said: Applying other countries antiquated approach to how they value and pay for medicines will stall investment across Americas biotech companies, risk access to vital treatments and cures for millions of American patients, and lead to fewer American jobs.A Roche spokesperson told Endpoints News the company may be rethinking a planned $50 billion manufacturing investment announced earlier this year because of U.S. policies.Companies themselves were quiet, caught as they are in a myriad of new policy battles ranging from tariffs to domestic manufacturing investments to new tax cuts. All of these policies could be rolled up in the massive budget reconciliation bill that is expected to move through Congress this year, which may require intensive negotiation as the year progresses.Which companies are most exposed?If the policy is imposed in commercial as well as government channels, any company that sells to U.S. consumers is exposed. Given that about two-thirds to three-quarters of pharmaceutical profits come from the U.S. market, thats just about every drugmaker.If its restricted to just Medicare, on the other hand, then the companies that make drugs commonly used by older people would have the greatest exposure. That includes developers affected by the first two rounds of IRA price negotiations, such as Johnson & Johnson, Bristol Myers Squibb, Novo Nordisk, Boehringer Ingelheim, AstraZeneca and AbbVie. '