Comparison of Adverse Effect Profiles of Nafcillin and Oxacillin in Pediatric Patients.

Objective: Data comparing the safety profiles of nafcillin and oxacillin are limited in the pediatric patient setting. This study was conducted to compare adverse effect profiles of nafcillin and oxacillin.

Methods: This was a single center retrospective study including patients admitted to a children's hospital who received either nafcillin or oxacillin. Patients were excluded if they were older than 18 years or if therapy duration was less than 48 hours. The primary objective was to compare the cumulative sum of adverse effects of nafcillin to oxacillin, including incidence of hypokalemia, nephrotoxicity, hepatotoxicity, neutropenia, infusion-related reactions, loss of intravenous access, and early discontinuation of therapy. Secondary endpoints included comparison of the incidence of each adverse effect collected.

Results: Fifty-three patient encounters (representing 46 patients) were included, with 17 patients receiving nafcillin and 36 patients receiving oxacillin. There was no difference between the cumulative sum of adverse effects for nafcillin (n = 16) and oxacillin (n = 45), p = 1. Acute kidney injury (AKI) occurred with both nafcillin and oxacillin at similar rates (21% vs 30%; p = 0.72), as well as hypokalemia for both nafcillin and oxacillin (50% vs 43%; p = 0.46). All but 1 patient who experienced AKI were receiving other nephrotoxin(s) during therapy. Changes in liver transaminases were not significant for either drug. A significant decline in median absolute neutrophil count was noted from pre to post treatment with oxacillin (8400 to 6000 cells/µL; p = 0.002).

Conclusions: Our study found no significant difference in adverse effects of nafcillin and oxacillin. Both treatment groups experienced AKI and hypokalemia. Larger studies are needed to determine if one drug is safer than the other.