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Headline

Merck discontinues Recarbrio in the U.S., raising concerns about treatment options for difficult-to-treat Gram-negative infections

Merck has discontinued production and U.S. marketing of Recarbrio (imipenem/cilastatin/relebactam), an intravenous antibacterial combination used for certain serious Gram-negative infections, including complicated urinary tract infections, complicated intra-abdominal infections, and hospital- or ventilator-associated bacterial pneumonia.

Merck said the decision was part of an “ongoing portfolio review” and was not related to safety or quality concerns. Remaining U.S. inventory was expected to be depleted by late September 2026. STAT

The development has particular implications for patients with difficult-to-treat Pseudomonas aeruginosa, for whom imipenem-relebactam has been an important treatment option.

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1-minute summary

• Recarbrio combines imipenem, cilastatin and relebactam.
• It was initially FDA-approved in 2019 for certain complicated urinary tract and intra-abdominal infections.
• In 2020, its indications were expanded to include hospital-acquired and ventilator-associated bacterial pneumonia. CIDRAP
• Pediatric use was subsequently added in 2025. Becker’s Hospital Review
• Merck is discontinuing the product in the United States.
• Merck stated that the decision was unrelated to product safety or quality.
• The discontinuation may reduce treatment flexibility for infections caused by resistant Gram-negative organisms, particularly difficult-to-treat P. aeruginosa.
• Infectious-disease experts cited in the report highlighted the economic difficulty of developing and maintaining antibiotics that are deliberately reserved for severe resistant infections.
• The episode has renewed attention on proposals such as the PASTEUR Act, which would use subscription-style government payments to support availability of important antimicrobials rather than relying primarily on sales volume. U.S. Senator Michael Bennet

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Why this matters

Antibiotics intended for highly resistant infections present an unusual commercial problem.

From an antimicrobial-stewardship perspective, physicians are encouraged to reserve newer agents for patients who genuinely need them. This helps preserve their effectiveness and slow the emergence of resistance.

However, the same stewardship strategy can mean that a newly developed antibiotic is used relatively infrequently, limiting its commercial revenue.

The discontinuation of Recarbrio therefore illustrates a broader tension between:

Antibiotic stewardship → lower utilization → limited sales → commercial pressure

while simultaneously:

Antimicrobial resistance → need for effective reserve antibiotics → need to maintain reliable access

The issue is not simply whether another antibiotic exists. For some resistant organisms, susceptibility patterns can leave clinicians with relatively few active agents.

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Study at a glance

This report is not a clinical research study. It is a pharmaceutical-market and antimicrobial-resistance development reported through interviews and secondary sources.

Current shortage/discontinuation information lists Recarbrio as a product to be discontinued by Merck, with the planned timing around late September 2026. Drugs.com

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Feature details

What is Recarbrio?

Recarbrio is a fixed combination of three agents:

The combination was developed to provide activity against selected difficult-to-treat Gram-negative infections.

Relebactam is particularly important because certain β-lactamases can compromise β-lactam antibiotics. The combination has therefore been used in settings where resistance substantially limits conventional treatment options. CIDRAP

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Regulatory history

The original FDA approval was granted in July 2019. Becker’s Hospital Review

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What the report found

The central development is that Merck will no longer manufacture and market Recarbrio in the United States.

Merck characterized the decision as part of an “ongoing portfolio review”, rather than a response to safety or quality problems.

The company also indicated that alternative therapeutic options remain available for the approved indications.

However, the clinical significance of losing an individual antimicrobial depends heavily on the organism, resistance mechanism and susceptibility profile of the infecting isolate.

That distinction is important: discontinuation does not mean that all patients previously receiving Recarbrio will lack an alternative. Rather, it removes one option from the antimicrobial armamentarium.

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The particular concern: difficult-to-treat Pseudomonas aeruginosa

In the Healio report, infectious-disease specialist Amesh A. Adalja, MD, FIDSA, identified difficult-to-treat Pseudomonas aeruginosa as an area of particular concern.

He said:

“The patients who lose the most are those with difficult-to-treat Pseudomonas aeruginosa.”

He further noted that imipenem-relebactam had been among the preferred agents for some such infections and could remain active against isolates resistant to other treatment options.

This should be interpreted as an expert assessment, rather than evidence from a new clinical trial.

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Clinical significance

The clinical effect of Recarbrio’s withdrawal will not be uniform.

Potentially greater impact

The loss may be more consequential when clinicians are dealing with:

• multidrug-resistant Gram-negative infections;
• difficult-to-treat P. aeruginosa;
• infections with limited susceptibility to available β-lactams;
• patients for whom toxicity or other characteristics make alternative agents less desirable;
• situations requiring an active intravenous antimicrobial based on susceptibility testing.

Potentially smaller impact

For infections with several reliably active alternatives, discontinuation of Recarbrio may have limited practical effect.

Therefore, antibiotic susceptibility testing remains central to selecting therapy.

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Why reserve antibiotics create a market problem

One of the most important concepts highlighted by this story is the conflict between stewardship and commercial sustainability.

A new antibiotic intended for resistant infections should ideally be used conservatively.

That produces a paradox:

Adalja described this problem in particularly direct terms:

“We rightly tell clinicians to hold drugs like this in reserve, but that same restraint guarantees a revenue stream too small to sustain them.”

He argued that the problem extends beyond an individual company.

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The PASTEUR Act

The Recarbrio discontinuation has also renewed attention on proposed U.S. antimicrobial policy.

The PASTEUR Act—the Pioneering Antimicrobial Subscriptions To End Upsurging Resistance Act—was reintroduced in 2026. The legislation is designed to encourage development of new antimicrobials targeting serious resistant infections while supporting appropriate antimicrobial use and availability. U.S. Senator Michael Bennet

The proposed model attempts to separate payment from the number of doses sold.

In simplified terms:

Traditional pharmaceutical model

More doses → more revenue

Subscription-style antimicrobial model

Guaranteed availability/value → contracted payment

This approach is intended to address the economic problem created when society wants a critically important antibiotic to be available but infrequently used.

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Expert perspective

Adalja argued that infectious-disease physicians would adapt to the loss of Recarbrio but with fewer options.

His assessment was:

“When the list of options is that short, every subtraction counts, because resistance keeps wearing down whatever remains.”

This statement reflects the broader antimicrobial-resistance challenge: resistance can progressively narrow the number of agents that remain reliably effective.

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Limitations

Several limitations should be considered when interpreting the report.

1. No new clinical trial

This is a news report based primarily on company information and expert interviews, not a randomized clinical trial or observational study.

2. No comparative outcome analysis

The report does not provide new comparative data showing that discontinuation of Recarbrio will increase mortality, treatment failure or other clinical outcomes.

3. The effect varies by pathogen

The significance of losing Recarbrio depends on antimicrobial susceptibility and the specific resistance mechanisms present.

4. Alternative therapies remain available

Merck has explicitly stated that alternatives remain for the approved indications. Becker’s Hospital Review

5. U.S.-specific development

The reported discontinuation concerns the U.S. market. It should not automatically be interpreted as a worldwide withdrawal.

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What doctors should know

1. Recarbrio is being withdrawn from U.S. commercial availability

Clinicians should not assume routine future access to Merck-supplied Recarbrio in the United States.

2. Do not equate discontinuation with a safety recall

Merck has stated that the decision was not because of safety or quality problems.

3. Review susceptibility results carefully

For serious resistant Gram-negative infections, treatment should be guided by:

• organism identification;
• antimicrobial susceptibility testing;
• resistance mechanism when available;
• infection site;
• severity of illness;
• renal function;
• prior antimicrobial exposure;
• local antibiogram and resistance patterns;
• infectious-disease consultation when appropriate.

4. Particular attention to difficult-to-treat Pseudomonas

The disappearance of another potentially active option may be particularly relevant when P. aeruginosa has a highly restricted susceptibility profile.

5. Alternatives should be individualized

The appropriate replacement cannot be determined simply by substituting another broad-spectrum antibiotic. Selection should depend on the pathogen and susceptibility profile.

6. Stewardship remains important

The discontinuation does not mean reserve antibiotics should be used more liberally. Appropriate antimicrobial stewardship remains essential to preserve existing agents.

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Recarbrio: clinical and market significance at a glance

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Bottom line

Merck’s discontinuation of Recarbrio removes another antimicrobial option from the U.S. treatment landscape for selected serious Gram-negative infections. The immediate clinical effect will depend on local resistance patterns and the availability of alternative agents, rather than affecting every patient previously eligible for Recarbrio.

The more fundamental issue highlighted by the decision is the unusual economics of antibiotics: the drugs that society most wants to preserve are often the drugs that generate the least revenue when used appropriately.

The Recarbrio case therefore illustrates why antimicrobial resistance is not only a microbiological and clinical problem but also a drug-development, market-access and health-policy problem. The proposed PASTEUR Act is one policy response intended to address that disconnect. U.S. Senator Michael Bennet

Original research / DOI

Not applicable. This is a news report/interview, not an original clinical research publication.

The underlying regulatory history and product information can be traced to FDA/Merck documentation; Merck’s 2026 postmarketing documentation identifies Recarbrio as imipenem/cilastatin/relebactam. merck.com