Vancomycin TZP Combo: Kidney Risk Not Related to Length of Infusion

Adding to research confirming the risk of administering piperacillin/tazobactam (TZP) in combination with vancomycin, two research teams reported that it does not matter whether the drugs are given in an extended infusion or standard infusion.

The drug combo is often used when patients are infected with methicillin-resistant staph or serious gram-negative infections. Clinicians had hypothesized that giving TZP through an extended infusion might be to blame for the higher rate of kidney injuries in these patients than is seen in patients receiving vancomycin with other beta-lactams. Two groups reporting at IDWeek 2015 in San Diego, CA, found that is not the case.

Mark Knaub, Pharm D, and colleagues at the Jesse Brown VA Medical Center in Chicago, IL, looked at patients getting the drugs in two different dosing strategies. One group got a standard infusion of 30 minutes of TZP every 4 to 6 hours. The other group got infusions lasting 4 hours delivered every 8 hours.

Though there appeared to be more risk associated with the longer infusions, the researchers concluded that the higher incidence of acute kidney injury in that group (29% vs. 15.7% in the group that got shorter infusion times) was due to more patients having multiple co-morbidities, including diabetes.

"This study did not find a difference in the incidence of acute kidney injury with different [TZP] dosing strategies, the team concluded.

A Detroit team led by Bhagyashri Navalee, MD, and colleagues at Wayne State University, Detroit, MI, reached a similar conclusion. TZP "delivered via extended infusion was associated with a similar risk of nephrotoxicity as [TZP] delivered by standard infusion," they wrote. Both studies were presented as abstracts at the meeting.

In a related study at the same institution, Jason Pogue, Pharm D, and colleagues (including Navalee) wrote that the injuries might be limited by using lower loading doses of vancomycin in appropriate patients and, when indicated, de-escalating or stopping vancomycin, TZP, or both on or before day 3 of therapy. That study involved 320 patients, of whom 105 developed acute kidney injury.