Screening assays are different from confirmatory tests such as gas chromatography/mass spectrometry (GC/MS) that can provide definitive identification of individual drugs and their metabolites [7]. Confirmatory tests are often more labor-intensive, technically demanding, and expensive compared with screening tests. For many EDs, confirmatory tests are available only by referral of patient samples to an off-site reference laboratory, such that turnaround time for results is often not fast enough to aid in real-time patient management. In the United States, there are currently marketed DOA/Tox screening immunoassays Inhibitors,research,lifescience,medical for 18 targets (i.e., single drugs or drug

classes) including: amphetamines, barbiturates, benzodiazepines, cocaine metabolite/benzoylecgonine, buprenorphine, cannabinoids, heroin metabolite/6-acetylmorphine (6-AM), lysergic acid diethylamide (LSD), MDMA/Ecstasy (3,4-methylenedioxymethamphetamine), methadone, Inhibitors,research,lifescience,medical methadone metabolite/EDDP (2-ethylidine-1,5-dimethyl-3,3-diphenylpyrrolidine), methaqualone, nicotine Inhibitors,research,lifescience,medical metabolite/cotinine, opiates, oxycodone, phencyclidine (PCP), propoxyphene, and TCAs. For some drugs or metabolites (e.g., buprenorphine, heroin metabolite/6-AM), there may be only one or two

manufacturers marketing an assay whereas for more common tests (e.g., amphetamines, benzodiazepines, opiates), there are many different marketed assays. Different assays for the same analyte may vary in terms of analytical sensitivity and specificity, leading to potential difficulties in clinical interpretation. DOA/Tox screening test is most often Inhibitors,research,lifescience,medical performed on urine but, in some cases, serum/plasma or saliva may be used [5,7,10]. DOA/Tox screening immunoassays may be designed by raising antibodies against a single drug or drug metabolite (‘target compound’). Alternatively, multiple target

compounds may be used to achieve broader detection of a class of drugs. There is a general trend towards use of monoclonal antibodies in marketed assays, but assays using polyclonal Inhibitors,research,lifescience,medical antibodies are still Ergoloid used widely in some cases [6,7]. Theoretically, use of monoclonal antibodies provides more consistent performance over polyclonal antibodies. DOA/Tox screening assays may be ATM Kinase Inhibitor mouse directed at classes of drugs such as amphetamines, barbiturates, benzodiazepines, cannabinoids, and opiates [7,10]. In these ‘broad specificity’ DOA/Tox assays, ideally the specificity of the assay is broad enough to detect a range of ‘within-class’ compounds but not too non-specific to cross-react with ‘out-of-class’ compounds that may have similar chemical structures. Other DOA/Tox screening assays are directed towards detection of a single target compound (drug or drug metabolite) without cross-reactivity with other similar structures.