The Trump regulation would tie what Medicare pays for certain drugs administered in a doctor's office to the lowest price paid among a group of economically advanced countries. It would apply to 50 medications that account for the highest spending under Medicare's Part B benefit for outpatient care. This group includes cancer drugs and other medications delivered by infusion or injection. Trump announced the policy at the White House before the Thanksgiving holiday, saying, "the drug companies don't like me too much. But we had to do it."

Blake wrote that the plaintiffs had established a reasonable likelihood that their arguments accusing the administration of cutting corners in a rush to regulate would carry the day in a trial. Federal law says that government agencies must provide adequate opportunity for affected parties to comment on proposed regulations. The administration had sought to use emergency authority as a work-around.

The Pharmaceutical Research and Manufacturers of America (PhRMA), the Association of Community Cancer Centers, the Global Colon Cancer Association and the National Infusion Center Association filed the motion for a temporary restraining order and preliminary injunction with an accompanying memorandum of law on December 10. The complaint cited three key concerns:

• The administration exceeded the authority granted to the Center for Medicare and Medicaid Innovation under the Affordable Care Act.
• The administration violated the U.S. Constitution by using a regulatory process to rewrite the Medicare statute and transform the reimbursement system for physician-administered medicines in the United States.
• The administration failed to demonstrate the "good cause" required for the interim final rule to skip important notice and comment procedures that allow the American public to weigh in on regulations.

Organizations such as PhRMA and the American Hospital Association welcomed the ruling. "Hospitals and health systems have very deep concerns about the substance and legality of this model, and the AHA filed a declaration with this lawsuit expressing how the model could negatively impact hospitals, health systems and the patients they care for," AHA executive vice president Tom Nickels said.

PhRMA executive vice president and general counsel James C. Stansel said, "We welcome Judge Blake's ruling in favor of a temporary restraining order regarding the Most Favored Nation Interim Final Rule. As the lawsuit continues, we continue to have grave concerns with this policy and the negative consequences it will have on America's patients, providers and future medical innovation."

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• 10 priciest drugs in America
• Curbing specialty drug spending: Where to start?
• The gap between list prices and net prices for drugs is widening