Risk of Nephrotoxicity Associated With Nonrenally Adjusted Intravenous Polymyxin B Compared to Traditional Dosing

Polymyxin B's package insert recommends renal adjustment. Contemporary studies suggest it does not require renal adjustment.

To determine whether time to acute kidney injury (AKI) differs between renally adjusted and nonadjusted intravenous (IV) polymyxin B.

This retrospective chart review compared time to AKI after renally adjusted and nonadjusted IV polymyxin B administration. It included patients who were 18 years or older, received IV polymyxin B, and had creatinine clearance below 80 mL/min, and excluded ones who had AKI, received renal replacement therapy, or were pregnant.

Fifty-four patients were included. There was not any statistical association between dosing type and time to AKI (P = .13). Incidence of nephrotoxicity, mortality, and length of stay (LOS) were higher in the renally adjusted arm (21.7% vs 6.5%, 17.4% vs 6.5%, and 16 vs 14 days, respectively). Four patients received concomitant ascorbic acid; not one developed AKI.

A significant association between IV polymyxin B dosing type and time to AKI was not found. Adverse events were higher in the renally adjusted arm. This suggests that nonadjusted IV polymyxin B may be preferred in patients with renal impairment. Ascorbic acid may mitigate IV polymyxin B's nephrotoxic potential. Further studies are needed to corroborate these findings.