Failure of amoxicillin to produce false-positive urine screens for cocaine metabolite

Gary M. Reisfield, Judella Haddad, George R. Wilson, Laura M. Johannsen, Kathryn L. Voorhees, Chris W. Chronister, Bruce A. Goldberger, James D. Peele, Roger L. Bertholf

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Amoxicillin has been causally linked in the lay and medical literature to false-positive urine drug screens for cocaine metabolites. An exhaustive search of the peer-reviewed medical literature revealed no data to support this link. We hypothesized that amoxicillin does not cause false-positive urine drug screens for cocaine metabolites. To test this hypothesis, we examined the urine of 33 subjects administered a course of amoxicillin, subjecting the specimens to four common urine screening immunoassays. Thirty-one specimens were negative for the cocaine metabolite, benzoylecgonine (BE), by all four screening methods; two were positive for BE by all four screening methods. Both positive specimens were confirmed by gas chromatography-mass spectrometry (GC-MS) for the presence of BE at > 150 ng/mL. Three specimens that screened negative, but produced absorbance values that were intermediate between negative and positive controls, were submitted for GC-MS analysis; BE was detected in all three specimens at concentrations of 54, 94, and 119 ng/mL. Twenty-eight specimens produced screening results indistinguishable from negative controls. Within the limitations of the study design, we conclude that amoxicillin is unlikely to produce false-positive urine screens for cocaine metabolites.

Original languageEnglish (US)
Pages (from-to)315-318
Number of pages4
JournalJournal of Analytical Toxicology
Volume32
Issue number4
DOIs
StatePublished - May 2008

ASJC Scopus subject areas

  • Analytical Chemistry
  • Environmental Chemistry
  • Toxicology
  • Health, Toxicology and Mutagenesis
  • Chemical Health and Safety

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