title: Immunoassay screening in urine for synthetic cannabinoids - an evaluation of the diagnostic efficiency.
abstract: BACKGROUND
  The abuse of synthetic cannabinoids (SCs) as presumed legal alternative to cannabis poses a great risk to public health. For economic reasons many laboratories use immunoassays (IAs) to screen for these substances in urine. However, the structural diversity and high potency of these designer drugs places high demands on IAs regarding cross-reactivity of the antibodies used and detection limits.
  
  
  METHODS
  Two retrospective studies were carried out in order to evaluate the capability of two homogenous enzyme IAs for the detection of currently prevalent SCs in authentic urine samples. Urine samples were analyzed utilizing a 'JWH-018' kit and a 'UR-144' kit. The IA results were confirmed by an up-to-date liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) screening method covering metabolites of 45 SCs.
  
  
  RESULTS
  The first study (n=549) showed an 8% prevalence of SCs use (LC-MS/MS analysis) among inpatients of forensic-psychiatric clinics, whereas all samples were tested negative by the IAs. In a second study (n=200) the combined application of both IAs led to a sensitivity of 2% and a diagnostic accuracy of 51% when applying the recommended IA cut-offs. Overall, 10 different currently prevalent SCs were detected in this population. The results can be explained by an insufficient cross-reactivity of the antibodies towards current SCs in combination with relatively high detection limits of the IAs.
  
  
  CONCLUSIONS
  In light of the presented study data it is strongly recommended not to rely on the evaluated IA tests for SCs in clinical or forensic settings. For IA kits of other providers similar results can be expected.
authors.affiliation: .
authors.forename: Florian
authors.initials: F
authors.lastname: Franz
authors.affiliation: .
authors.forename: Verena
authors.initials: V
authors.lastname: Angerer
authors.affiliation: .
authors.forename: Hanna
authors.initials: H
authors.lastname: Jechle
authors.affiliation: .
authors.forename: Melanie
authors.initials: M
authors.lastname: Pegoro
authors.affiliation: .
authors.forename: Harald
authors.initials: H
authors.lastname: Ertl
authors.affiliation: .
authors.forename: Georg
authors.initials: G
authors.lastname: Weinfurtner
authors.affiliation: .
authors.forename: David
authors.initials: D
authors.lastname: Janele
authors.affiliation: .
authors.forename: Christian
authors.initials: C
authors.lastname: Schlögl
authors.affiliation: .
authors.forename: Matthias
authors.initials: M
authors.lastname: Friedl
authors.affiliation: .
authors.forename: Stefan
authors.initials: S
authors.lastname: Gerl
authors.affiliation: .
authors.forename: Reinhard
authors.initials: R
authors.lastname: Mielke
authors.affiliation: .
authors.forename: Ralf
authors.initials: R
authors.lastname: Zehnle
authors.affiliation: .
authors.forename: Matthias
authors.initials: M
authors.lastname: Wagner
authors.affiliation: .
authors.forename: Bjoern
authors.initials: B
authors.lastname: Moosmann
authors.affiliation: .
authors.forename: Volker
authors.initials: V
authors.lastname: Auwärter
mesh_terms: D002186:Cannabinoids / Q000737:chemistry / Q000378:metabolism / Q000652:urine*; D006801:Humans; D007118:Immunoassay; D012189:Retrospective Studies; D021241:Spectrometry, Mass, Electrospray Ionization; D015813:Substance Abuse Detection; D053719:Tandem Mass Spectrometry
chemical_list: D002186:Cannabinoids
keywords: LC-MS/MS; abstinence control; drug screening; immunoassay; synthetic cannabinoids; urine analysis