1407. Disproportionality Analysis of Safety with Nafcillin and Oxacillin with the FDA Adverse Event Reporting System (FAERS)
Session: Poster Abstract Session: PK/PD Studies
Friday, October 5, 2018
Room: S Poster Hall
  • Timbrook IDWeek 2018.pdf (317.5 kB)
  • Background: Antistaphylococcal penicillins including oxacillin and nafcillin are among the drugs of choice for severe and invasive MSSA infections. While alternative agents such as cefazolin are associated with improved safety compared to antistaphylococcal penicillins, comparative safety data between individual antistaphylococcal penicillins is limited and has shown possible improved safety with oxacillin among adults. The objective of this study was to determine the relative adverse events (AEs) reporting for these agents among the FDA Adverse Event Reporting System (FAERS) database.

    Methods: We reviewed adverse events reports from the FAERS database from Q4/2003-Q1/2018 and performed a disproportionality analysis of safety events for nafcillin and oxacillin including ADEs related to acute kidney injury (AKI), rash, hypokalemia, and hepatotoxicity. Measures of association evaluated included reporting odds ratio (ROR) and proportion reporting ratio (PRR).

    Results: Reports of AKI were substantially more common with nafcillin (PRR 23.2, 95% CI 18.4 – 29.3) than oxacillin (PRR 10.9, 95% CI 7.6 – 15.5). Rash was slightly higher with nafcillin than oxacillin (PRR 3.7, 95% CI 2.8 – 5.1 vs 2.6, 95% CI 1.8 – 3.8). Hypokalemia was substantially more common with nafcillin than oxacillin (PRR 11.8, 95% CI 7.1 – 19.4 vs 1.6, 95% CI 0.4 – 6.4). Hepatotoxcitiy was slightly higher reported among nafcillin than oxacillin (PRR 25.3, 95% CI 14.5 – 44.3 vs 12.9, 95% CI 5.8 – 28.6). Similar observations were seen with RORs (Figure 1).

    Figure 1. Reporting Odds Ratios of AEs with Nafcillin and Oxacillin

    Conclusion: Oxacillin may be associated with overall improved safety compared to nafcillin based on reporting signals from FAERS. Our results support previous limited observational data. With the likely equal efficacy of these agents, clinicians may want to consider prescribing oxacillin over nafcillin if an antistaphylococcal penicillin is indicated for an invasive MSSA infection. However, given the limitations of reporting systems, further evaluation is warranted.    

    Tristan T. Timbrook, PharmD, MBA, BCPS, University of Utah Health Care, Salt Lake City, UT, Jesse Sutton, PharmD, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, UT and Emily Spivak, MD, MHS, Internal Medicine, University of Utah Health, Salt Lake City, UT


    T. T. Timbrook, None

    J. Sutton, None

    E. Spivak, None

    See more of: PK/PD Studies
    See more of: Poster Abstract Session

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 3rd with the exception of research findings presented at the IDWeek press conferences.