Jennifer M Colby1, Pratish C Patel2, Darwin Y Fu3, Nicola J Rutherford4. 1. Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1301 Medical Center Drive, Nashville, TN 37232, United States. Electronic address: jennifer.colby@vumc.org. 2. Department of Pharmaceutical Services, Vanderbilt University Medical Center, 1301 Medical Center Drive, Nashville, TN 37232, United States. 3. Department of Biomedical Informatics, Vanderbilt University Medical Center, 1301 Medical Center Drive, Nashville, TN 37232, United States. 4. Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1301 Medical Center Drive, Nashville, TN 37232, United States.
Abstract
OBJECTIVES: Fluoroquinolone antibiotics are commonly used in the treatment of infections and have previously been confirmed to cross-react with previous generations of opiates immunoassays. In this work we evaluated the cross-reactivity of the three fluoroquinolones in use at our institution with a panel of 10 urine drug screens. DESIGN AND METHODS: Drug preparations of levofloxacin, ciprofloxacin, and moxifloxacin that were designed for intravenous delivery were added to drug-free urine at varying concentrations. Spiked urine samples were screened for illicit and therapeutic drugs on an Abbott Architect c16000 automated chemistry analyzer. Percent cross-reactivity was calculated. RESULTS: Levofloxacin displayed clinically relevant cross-reactivity with the Abbott MULTIGENT opiates and Thermo CEDIA® buprenorphine immunoassays but did not cross-react with the Abbott MULTIGENT oxycodone or methadone immunoassays. Moxifloxacin displayed clinically relevant cross-reactivity only with the Abbott MULTIGENT amphetamine/methamphetamine assay. Ciprofloxacin did not cross-react with any of the 10 immunoassays. CONCLUSIONS: This study demonstrates that levofloxacin cross-reacts with modern immunoassays for two related opioids (buprenorphine and morphine) and moxifloxacin cross-reacts with the amphetamine/methamphetamine assay. Urine concentrations of these fluoroquinolones that are consistent with therapeutic use produced results above commonly used-cutoffs for positivity. This underscores the necessity of confirmatory testing of presumptively positive urine drug screens.
OBJECTIVES:Fluoroquinolone antibiotics are commonly used in the treatment of infections and have previously been confirmed to cross-react with previous generations of opiates immunoassays. In this work we evaluated the cross-reactivity of the three fluoroquinolones in use at our institution with a panel of 10 urine drug screens. DESIGN AND METHODS: Drug preparations of levofloxacin, ciprofloxacin, and moxifloxacin that were designed for intravenous delivery were added to drug-free urine at varying concentrations. Spiked urine samples were screened for illicit and therapeutic drugs on an Abbott Architect c16000 automated chemistry analyzer. Percent cross-reactivity was calculated. RESULTS:Levofloxacin displayed clinically relevant cross-reactivity with the Abbott MULTIGENT opiates and Thermo CEDIA® buprenorphine immunoassays but did not cross-react with the Abbott MULTIGENT oxycodone or methadone immunoassays. Moxifloxacin displayed clinically relevant cross-reactivity only with the Abbott MULTIGENT amphetamine/methamphetamine assay. Ciprofloxacin did not cross-react with any of the 10 immunoassays. CONCLUSIONS: This study demonstrates that levofloxacin cross-reacts with modern immunoassays for two related opioids (buprenorphine and morphine) and moxifloxacin cross-reacts with the amphetamine/methamphetamine assay. Urine concentrations of these fluoroquinolones that are consistent with therapeutic use produced results above commonly used-cutoffs for positivity. This underscores the necessity of confirmatory testing of presumptively positive urine drug screens.