Merck pulls last-resort antibiotic Recarbrio from US market, citing no safety issue

Merck has stopped manufacturing and marketing Recarbrio, an injectable antibiotic held in reserve for some of the hardest-to-treat bacterial infections, in the United States. The company confirmed the withdrawal this week, telling clinicians that alternative treatments remain available and that patients on the drug should consult their doctors about next steps.

Merck said the decision came out of an ongoing review of its product portfolio and was not related to any safety or manufacturing problem. The company has never disclosed Recarbrio's US sales figures in its financial filings, an omission that infectious-disease physicians say reflects how rarely the drug was actually used, even though Merck touted the drug as an important new option for clinicians when the Food and Drug Administration first approved it in 2019.

The numbers behind the exit

Recarbrio combines an older antibiotic, imipenem-cilastatin, with relebactam, a compound built to disable resistance enzymes such as Klebsiella pneumoniae carbapenemase, or KPC. The FDA approved it in 2019 for complicated urinary tract and abdominal infections, added hospital-acquired and ventilator-associated pneumonia in 2020, and, after Merck completed years of additional pediatric trials, cleared it for children weighing as little as 2 kilograms in 2025. The FDA's own tracking system already lists imipenem, cilastatin and relebactam injection as currently in shortage, a sign of how thin the supply had become even before Merck's discontinuation was made public.

The public-health stakes are set by a larger figure: the Centers for Disease Control and Prevention has estimated that antimicrobial-resistant infections sicken more than 2.8 million people in the United States every year and kill more than 35,000, with several resistant pathogens rising further through the pandemic years. Behind Recarbrio's pediatric label, meanwhile, sits a familiar problem: a 2025 study in the journal Antibiotics found that small and midsize drug companies, which now drive most new antibiotic development, completed only 2 of 20 required follow-up pediatric studies over a median of more than six years, a 10 percent completion rate.

How the antibiotic market got here

The withdrawal fits a pattern that antimicrobial researchers have warned about for years. Regulators and hospital stewardship programs deliberately hold newer antibiotics like Recarbrio in reserve, prescribing them only when older drugs fail, so that bacteria are slower to evolve resistance to them. That approach is sound medicine, but it also means a drug can win approval, prove effective and still generate too little revenue to justify keeping it on the market. Achaogen, a biotech that won FDA approval for its own antibiotic, plazomicin, in 2018, filed for bankruptcy within a year after sales failed to materialize, a collapse widely cited since as a warning sign for the field.

Because eligible patients are relatively few and stewardship rules discourage routine use, most new antibiotics sit on pharmacy shelves for long stretches between prescriptions. Large companies can absorb that cost for a time; smaller ones generally cannot, which is part of why so few small firms have completed the pediatric studies regulators require after approval.

Who is affected

The clearest effect falls on hospitals treating patients with multidrug-resistant gram-negative infections, particularly those involving carbapenem-resistant Enterobacterales that carry the KPC resistance mechanism, and Pseudomonas aeruginosa, a bacterium that causes severe pneumonia and bloodstream infections in critically ill patients. Physicians treating children with the most severe resistant infections lose an option that took Merck years and considerable expense to formally extend to pediatric dosing. Hospital pharmacists and antimicrobial stewardship teams will need to revise treatment protocols that had included Recarbrio as a preferred agent for certain infections.

What specialists are saying

Infectious-disease physicians offered differing assessments of how much the loss will be felt. Amesh Adalja, an infectious-disease physician and senior scholar at the Johns Hopkins University Center for Health Security, called the resulting clinical gap "immediate but narrow," noting that clinicians still have ceftazidime-avibactam, meropenem-vaborbactam and cefiderocol for KPC-producing infections. He said the loss would be felt most acutely in treating Pseudomonas aeruginosa, for which the drug had been one of a short list of preferred options.

Brad Spellberg, chief medical officer at Los Angeles General Medical Center, was more skeptical of the drug's value from the outset, saying it was "not in any way meaningfully differentiated from multiple other drugs on the market" and that he was not surprised by its exit.

Others framed the withdrawal as evidence of a deeper structural failure in how the United States pays for antibiotics.

"We appropriately reserve new antibiotics for patients who truly need them, but that means these medicines will sit on the shelf for long periods and generate little revenue," said Henry Skinner, chief executive of the AMR Action Fund, a nonprofit formed by pharmaceutical companies to invest in antibiotic development.

Skinner said he was especially concerned about pediatric care, noting that Merck had done "the long, costly work required" to expand Recarbrio's label to children as small as 2 kilograms, and asking who would generate similar evidence for future antibiotics if large companies cannot sustain such products commercially.

What happens next

Both Adalja and Skinner pointed to the same proposed fix: a bill in Congress, reintroduced this year as the Pioneering Antimicrobial Subscriptions to End Upsurging Resistance Act, known as the PASTEUR Act, which would have the federal government pay drugmakers fixed annual amounts for critical-need antibiotics regardless of how many doses are actually dispensed, decoupling revenue from sales volume. First introduced in 2020, the bill has drawn bipartisan support in multiple sessions of Congress but has never passed.

"Until it or something like it becomes policy, more exits like this will come, which means fewer new antibiotics," Adalja said, a warning echoed across infectious-disease circles, as STAT News reported in its own account of the withdrawal earlier this week. For now, hospitals are left managing an immediate transition. A Merck spokesperson said alternative therapeutic options remain available for Recarbrio's approved uses and urged patients currently on the drug to consult their healthcare providers about the appropriate course of action, a message first reported by CIDRAP News, the infectious-disease publication at the University of Minnesota. No timeline has been set for when existing hospital supplies of Recarbrio will be exhausted.