Chemistry and Life

Medicinal chemistry. Pharmacology. Toxicology. Environmental sciences.

Ceftolozane and tazobactam

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Ceftolozane (top) and tazobactam (bottom)

Ceftolozane (top) and tazobactam (bottom)

In writing about antibiotics recently, I wanted to know more about what exactly the pharmaceutical industry is doing currently in terms of developing new antibiotics.  Ceftolozane appears to be one of the new drugs that is nearest getting FDA approval.

Ceftolozane (CXA-201) is an antibiotic currently under development by Cubist Pharmaceuticals.  According to Cubist, it is being targeted toward treatment of complicated urinary tract infections, complicated intra-abdominal infections, and ventilator-associated pneumonia. Ceftozolane is a cephalosporin antibiotic – a class of drugs for which there are already many available.  Cephalosporins are in the broader class known as beta-lactam antibiotics.  Some types of bacteria can limit the effectiveness of beta-lactam antibiotics through the action of an enzyme called beta-lactamase.  Basically, the bacteria break up the beta-lactam chemical group, destroying its effectiveness.

Ceftolozane is being studied for use in combination with tazobactam. Tazobactam has only weak antibiotic activity itself, but it acts as an inhibitor of beta-lactamase.  It prevents the bacteria from using the enzyme to resist beta-lactam antibiotics.  So the combination is more effective and broader in scope of activity than either of the two drugs alone.  Tazobactam is already used in combination with the antibiotic piperacillin.  The combination is marketed as Zosyn in the US.

Ceftolozane looks like it is well on the way to FDA approval and it will likely be useful certain types of infections.  But it doesn’t represent a breakthrough in fighting bacteria.  It is not a novel chemical class, it doesn’t have a novel mechanism of action, and the idea of combining it with a beta-lactamase inhibitor is already proven.


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