Merck's new combo med Recarbrio fights resistant bacteria. Can it tackle the sales challenge, too?

Merck & Co. is one of the few large drugmakers still pursuing antibacterial R&D, and on Wednesday, the company scored approval for a combo drug that tackles serious urinary tract and abdominal infections when other treatments don't work. 

The FDA signed off on Merck’s Recarbrio, which adds a new infection-fighter, relebactam, to a previously approved combo of cilastatin and imipenem. The three-ingredient combo med has a green light to tackle infections in adults caused by specific gram-negative bacteria.

Merck's newest nod comes on the heels of a Zerbaxa label expansion last month. The FDA added certain types of pneumonia to Zerbaxa's list of approvals in complicated UTIs and abdominal infections. The label boost gives Zerbaxa, acquired in Merck's $8.5 billion Cubist buyout, a chance to make up for early sales shortfalls.

Zerbaxa's marketing struggles show one reason why so many drugmakers are abandoning anti-infective research, even at a time when the need for new meds is so great. Speaking with FiercePharma earlier this summer, Merck’s associate vice president in infectious disease clinical research Dr. Joan Butterton said antibacterial resistance is “one of the great public health challenges of the modern era.”

Recarbrio itself illustrates that challenge; it was developed to address imipenem's waning effectiveness. Adding relebactam to the mix restores bacteria's susceptibility to imipenem, a spokeswoman said. Imipenem and cilastatin have been approved in combo for decades as Primaxin.

And Recarbrio is intended to be used almost as a last resort, which naturally limits its market and sales potential. The FDA’s director for the Office of Antimicrobial Products said it’s important the drug “be reserved for situations when there are limited or no alternative antibacterial drugs for treating a patient’s infection.”

Butterton said she’d been working on Recarbrio since 2009, and Merck itself has been in the anti-infectives development field for 80 years.

Recarbrio scored a Qualified Infectious Disease Product designation, a program at the agency intended to help usher antibacterial and antifungal drugs to market.

RELATED: Years after Cubist buyout, Merck scores a new Zerbaxa indication. Can it jump-start sales?

Scientists must keep making new antibacterials to stay out ahead of antimicrobial resistance, Butterton said, but existing payment systems for the drugs are flawed. Many companies haven’t seen a return on their investment in antibacterial R&D and have gone bankrupt.

To address that issue, Butterton cited a “delinkage” model being explored in the U.K. as a possible solution. The model offers annual lump-sum payments to drugmakers for antibacterials, rather than prescription-by-prescription payments. Then, the government can use as much or as little drug as needed. The model is similar to “subscription” purchasing systems that U.S. states have negotiated with hep C drugmakers for access to their therapies.