Friday November 23, 2007

Q; Which antibiotic may give false positive urine drug screen for opiates ?

A; Gatifloxacin (Tequin) and other fluoroquinolones.

Fluoroquinolones as a class are among compounds that have a propensity to cross-react with enzyme immunoassay urine drug screens for opiates. The exact mechanism is unknown.False-positive results could have negative effects on patient care so analysis with another assay method should be done to verify the urine drug screen.

Editors' note: Tequin has been taken off USA market last year but as mentioned in JAMA's article (reference # 2), 13 quinolones were tested and 11 of the 13 quinolones caused some opiate activity by at least 1 assay system. So be careful with all quinolones. Actually, JAMA report mentioned Levaquin as one of the top 3 !