Journal Article

The Trazodone Metabolite <i>meta</i>-Chlorophenylpiperazine Can Cause False-Positive Urine Amphetamine Immunoassay Results

Jason M. Baron, David A. Griggs, Andrea L. Nixon, William H. Long and James G. Flood

in Journal of Analytical Toxicology

Volume 35, issue 6, pages 364-368
Published in print July 2011 | ISSN: 0146-4760
Published online July 2011 | e-ISSN: 1945-2403 | DOI:
The Trazodone Metabolite meta-Chlorophenylpiperazine Can Cause False-Positive Urine Amphetamine Immunoassay Results

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Amphetamines and methamphetamines are part of an important class of drugs included in most urine drugs of abuse screening panels, and a common assay to detect these drugs is the Amphetamines II immunoassay (Roche Diagnostics). To demonstrate that meta-chlorophenylpiperazine (m-CPP), a trazodone metabolite, cross-reacts in the Amphetamines II assay, we tested reference standards of m-CPP at various concentrations (200 to 20,000 µg/L). We also tested real patient urine samples containing m-CPP (detected and quantified by HPLC) with no detectable amphetamine, methamphetamine, or MDMA (demonstrated by GC-MS). In both the m-CPP standards and the patient urine samples, we found a strong association between m-CPP concentration and Amphetamines II immunoreactivity (r = 0.990 for the urine samples). Further, we found that patients taking trazodone can produce urine with sufficient m-CPP to result in false-positive Amphetamines II results. At our institution, false-positive amphetamine results occur not infrequently in patients taking trazodone with at least 8 trazodone-associated false-positive results during a single 26-day period. Laboratories should remain cognizant of this interference when interpreting results of this assay.

Journal Article.  0 words. 

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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