Can Recarbrio Be a Panacea for Complicated Urinal Tract Infection?

R&D of Merck & Co wins in the battle between humans and ingenious bacteria, at least for now.

Development of new antibacterial drugs is a challenge of the early 21st century. Although the range of antibiotics is increasing year after year, the race for better treatment options can be never finished, as bacteria become resistant and, after some time, traditional preparations are no longer effective. That is why the FDA supports the clinical development of drugs for infections of different genesis, including Complicated Urinal Tract Infections (cUTIs).


In July 2019, the FDA approved Merck’s Recarbrio® for treatment of cUTIs in patients who have resistance to traditional medication plans. It will be available for sale in late 2019. But receiving QIDP designation does not necessarily mean that medication will be successful commercially and therapeutically.

Complicated UTIs versus Simple UTIs

Urinary Tract Infections are more common in women. The obvious example of simple UTI is cystitis of different genesis. UTIs are caused by Gram-negative bacteria that get to urinary tract or kidney. Simple infections can be treated with a short course of anti-bacterial drugs, such as nitrofurantoin (marketed as Macrobid and Furadantin), sulfamethoxazole-trimethoprim (Bactrim DS), fosfomycin (Monurol), cephalosporin of the third generation, and others.

The definition of complicated UTIs is quite vague. Any urinary infections that are chronic and resistant to the therapy can be considered complicated.

UTIs also include:

  • Pyelonephritis (kidney inflammation).
  • Complications associated with diabetes.
  • Complications associated with pregnancy.
  • Functional changes of the urinary tract.
  • Sepsis.

Urinary infections in men are less common but always complicated due to the different structure of the urinary tract. Complicated UTIs are subject to long-term (up to 6 months) treatment with antibiotics and complex antibacterial drugs.

Treatment Options for cUTIs

For outpatients, complex treatment is assigned, including:

  • One time IV injection of aminoglycoside, ceftriaxone, or fluoroquinolone.
  • Oral antibiotics (5–7 days), such as fluoroquinolones (levofloxacin or ciprofloxacin).
  • Trimethoprim/sulfamethoxazole for 14 days.

Although effective, quinolones have many serious side effects and recommended by the FDA only in cases when other options are failed.

For acute infections treated in hospital, injectable versions of quinolones are used that still affect tendons and muscles, as well as the nervous system, but have fewer side effects involving the digestive tract. The course for acute pyelonephritis may include:

  • IV fluoroquinolone
  • Extended-spectrum penicillin
  • Aminoglycoside
  • Ceftolozane/tazobactam (3rd generation cephalosporin)

Why Recarbrio is Special?

The goal of the developers was to find effective medicine to treat resistant bacteria with fewer complications. Recarbrio is a combination injectable drug for IV injections including three components:

  • Imipenem (a penem antibiotic).
  • Ilastatin (an inhibitor of renal enzyme dehydropeptidase).
  • Relebactam (a betalactamase inhibitor).

FDA approved Recarbrio for serious life treating infections when other treatments were ineffective. The challenge of Recarbrio combo was in adding relabactam to supplement imipenem and ilastatin that were already used together in Primaxin. It is expected that a new ingredient can enhance the effectiveness of an antibiotic to combat bacteria that have already developed resistance to a wide spectrum of antibiotics.

The competitiveness of Recarbrio comparing to previously used antibacterial agents remains questionable, though promising. In two clinical trials, it showed high effectiveness and, probably, fewer side effects than fluoroquinolones, but common side effects still include headache, vomiting, diarrhea, nausea, pyrexia, phlebitis/infusion site reactions, and hypertension.

Pharmaceutical companies are not very enthusiastic about developing new antibacterial drugs, as they are difficult to market. Previously, Merck & Co already had struggle while promoting Zerbaxa (ceftolozane/tazobactam), but it was improved after FDA additionally approved Zerbaxa for some pulmonary diseases.

The management of Merck & Co refrains from commenting on their commercial perspectives with Recarbrio. Recarbrio has also been approved for intra-abdominal infections, which gives it wide perspectives, but it is not time yet to conclude whether the medication can be a panacea for those patients who before had limited or no treatment options for complicated urinary tract infections.