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False-positive phencyclidine (PCP) on urine drug screen attributed to desvenlafaxine (Pristiq) use
  1. T Michael Farley1,2,
  2. Emily N Anderson1,
  3. Jade N Feller1
  1. 1Department of Pharmacy Practice and Science, University of Iowa College of Pharmacy, Iowa, USA
  2. 2Department of Pharmacy, Mercy Hospital, Iowa, USA
  1. Correspondence to Dr T Michael Farley, mike-farley{at}


We report a likely false-positive phencyclidine (PCP) result detected with a urine drug screen (UDS) (Medtox, St Paul, Minnesota, USA) in the setting of therapeutic desvenlafaxine (Pristiq) use. Desvenlafaxine (O-desmethylvenlafaxine) is the active metabolite of venlafaxine (Effexor). Prior reports have confirmed venlafaxine use resulting in a false-positive for PCP on a UDS. However, there has been a paucity of reporting of commercially available desvenlafaxine formulations (Pristiq, Khedezla) resulting in false-positives for PCP on a UDS.

  • psychiatry (drugs and medicines)
  • general practice / family medicine
  • drug misuse (including addiction)
  • toxicology

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  • Contributors Conception or design: TMF. Analysis or interpretation of data: TMF, JNF, ENA. Drafting the work and revisions: TMF, JNF, ENA. Final approval of the version published: TMF, JNF, ENA. All authors made substantial contributions to this work. All authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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