Amphetamine Positive Urine Toxicology Screen Secondary to Atomoxetine

Abstract

The aim of this paper is to report the first case of atomoxetine leading to false-positive urine drug screen. An otherwise healthy 27-year-old female with a history of attention deficit hyperactivity disorder (ADHD) treated with atomoxetine had an acute onset tonic-clonic seizure. On arrival to the hospital, a urine toxicological drug screen with immunochemical cloned enzyme donor immunoassay (CEDIA) was performed. Results were positive for amphetamines; however, the presence of these substances could not be confirmed with urine gas chromatography-mass spectrometry (GC-MS). She denied any illicit drug use, herbal medications, or supplements, and her other prescription medications have not been previously known to cause a false-positive result for amphetamines. While stimulant treatments for ADHD could certainly result in a positive result on urine screen for amphetamines, there have been no reports of false-positive results for amphetamines secondary to patients using atomoxetine. We implicate atomoxetine, and/or its metabolites, as a compound or compounds which may interfere with urine drug immunoassays leading to false-positive results for amphetamines CEDIA assays.

What Can a Urine Drug Screening Immunoassay Really Tell Us?

“…The use of urine drug screening in less acute situations and legal settings also needs to be evaluated with the same set of clinical resources in order to reach accurate conclusions to assure that the resulting actions that are taken by the clinician or by the law are warranted. Amantidine 22 , atomoxetine 23 , bupropion 24,25 , chloroquine 26 , ephedrine 27 , pseudoephedrine 27 , phenylephrine 27 , metformin 28 , phentermine 29 , ranitidine 30 , selegiline 31 , labetalol 32 , some phenothiazines (chlorpromazine 33 , promethazine 33 ), trazodone 34,35 , and some tricyclic antidepressants (doxepin 22,36 , desipramine 22,36 ) MDA 5 , MDMA (''ecstasy'' or ''molly'') and its derivatives 5 , substituted phenethylamine derivatives 5,9,37 (''bath salts'' and ''2C'' drugs)…”

Guilty or not guilty? — False positive results of common medicines in drug tests: review and practical guide

“…While stimulant treatments for ADHD can result in positive amphetamine urine screens, there are no known reports of false positives specifically linked to atomoxetine. The study suggests that atomoxetine or its metabolites may interfere with UDS immunoassays, causing F/P amphetamine results in cloned enzyme donor immunoassay assays [11].…”

Patients in medical treatment for attention deficit/hyperactivity disorder (ADHD): Are they at risk in drug screening?

“…We identified one study concerning atomoxetine and 'false positive' screening results on immunoassays. The study was based on a single case report (Fenderson et al 2013). According to the World Health Organization, single case studies represent the lowest level of evidence (WHO 2000).…”

“…She denied to have taken illicit drugs, herbal medications or any over-the-counter drugs. The blood concentration of atomoxetine and metabolites was not analysed (Fenderson et al 2013) Bupropion Reported to cause 'false positive' results for 'amphetamines' (amphetamine/methamphetamine) and LSD In a review on 'false positive' urine screens (Brahm et al 2010), two studies with relevance to bupropion were mentioned (Nixon et al 1995;Weintraub and Linder 2000) Case studies A male with history of polydrug use and with a prescribed dose of 300 mg bupropion per day (for 3 weeks) was found positive for 'amphetamines' during a routine drug screen using an automated monoclonal EMIT II immunoassay, but confirmatory emergency toxicology testing with liquid chromatographic and photo-diode array detection did not confirm this finding. Cross-reactivity by bupropion and three metabolites were further investigated and found to cross-react with the EMIT II immunoassay.…”