False-positive EMIT II opiates from ofloxacin.
The cross-reactivities of four quinolone antibiotics--ofloxacin, norfloxacin, ciprofloxacin, and nalidixic acid--toward the EMIT II Opiates enzyme immunoassay were examined. Drug-free urine was spiked with the individual drugs up to 5,000 mg/L. Only ofloxacin showed potential for causing a false-positive opiates immunoassay screening result (apparent morphine > 300 micrograms/L). The method produced a positive opiate result at an ofloxacin concentration of 200 mg/L, a 0.16% cross-reactivity. Three hospitalized patients taking therapeutic doses of ofloxacin all gave false-positive EMIT II Opiates urine screening results. Three patients taking norfloxacin and three patients taking ciprofloxacin gave true-negative urine screening results. False-positive results were also obtained from the urines of two volunteers who each consumed a single 400-mg ofloxacin pill.
Meatherall
R
R
Department of Biochemistry, St. Boniface General Hospital, Winnipeg, Canada.
Dai
J
J
D000890:Anti-Infective Agents / Q000652:urine*; D000906:Antibodies / Q000276:immunology; D002939:Ciprofloxacin / Q000652:urine; D003429:Cross Reactions; D017248:Enzyme Multiplied Immunoassay Technique; D005189:False Positive Reactions; D006801:Humans; D009020:Morphine / Q000652:urine*; D009268:Nalidixic Acid / Q000652:urine; D009643:Norfloxacin / Q000652:urine; D015242:Ofloxacin / Q000652:urine*
D000890:Anti-Infective Agents; D000906:Antibodies; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D009020:Morphine; D015242:Ofloxacin; D009643:Norfloxacin