Crossreactivity of bupropion metabolite with enzyme-linked immunosorbent assays designed to detect amphetamine in urine

Background: Drug screening is rapid, inexpensive, and is often used in clinical, forensic, and workplace drug testing to gain informative results. This article seeks to determine if bupropion and/or its metabolites is resulting in false-positive amphetamine screening results in our case samples using commercially available enzymelinked immunosorbent assay tests. Method: Fortified urine and forensic case samples were used to determine crossreactivity of bupropion and its main metabolite to four different amphetamine and methamphetamine enzyme-linked immunosorbent assay kits. Results: Two of the enzyme-linked immunosorbent assay kits used to screen for amphetamine may result in false-positive results if bupropion metabolites are present in concentrations greater than 500 ng/mL. Three case samples gave a positive screen results for amphetamine using Amphetamine ULTRA kits, yet no amphetamines were confirmed by gas chromatography-mass spectrometry and all samples were positive for bupropion and metabolites. Conclusions: Laboratory directors and clinicians should be aware of the characteristic of their chosen laboratory assay and should communicate this to physicians so that results can be interpreted accurately.