Title: Drug Abuse Screens<br/>Author: Kishan Kapadia<br/><a href='http://umem.org/profiles/faculty/1143/'>[Click to email author]</a><hr/><table border="1" cellpadding="0" cellspacing="0">
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<strong>Performance Characteristics of Common Drug Abuse Screening Immunoassays</strong></p>
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<strong>Drug/Class</strong></p>
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<strong>Detection Interval (<span style="color:#ff0000;">***</span>)</strong></p>
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<strong>Comments</strong></p>
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<strong>Amphetamines</strong></p>
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1-2 days (2-4 days)</p>
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Decongestants, ephedrine,<em>l</em>-methamphetamine, selegilene & bupropion metabolites may give False (+) results; MDA & MDMA are variably detected</p>
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<strong>Barbiturates</strong></p>
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2-4 days</p>
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Phenobarbital may be detected for up to 4 weeks</p>
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<strong>Benzodiazepines</strong></p>
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1-30 days</p>
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Benzos vary in reactivityand potency; False (+) results may be seen with oxaprozin</p>
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<strong>Cannabinoids</strong></p>
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1-3 days (>1 month)</p>
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Screening assays detect inactive and active cannabinoids; Confirmatory assays detects inactive metabolite THCA (tetrahydrocannabinoic acid)</p>
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<strong>Cocaine </strong> </p>
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2 days (1 week)</p>
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Screening & confirmatory assays detect inactive metabolite BE (benzoylecgonine); False (+) results are unlikely</p>
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<strong>Opiates</strong></p>
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1-2 days; 2-4 days (<1 week)</p>
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Semisynthetic opiates derived from morphine show variable cross-reactivity; Fully synthetic opioids (e.g., fentanyl, meperidine, methadone, propoxyphene, tramadol) have minimal cross reactivity; Quinolone may cross-react</p>
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<strong>Methadone</strong></p>
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1-4 days</p>
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Doxylamine may cross-react</p>
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<strong>Phencyclidine</strong></p>
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4-7 days (>1 month)</p>
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Dextromethorphan, diphenhydramine, ketamine, & venlafaxine may cross react</p>
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<strong>Propoxyphene</strong></p>
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3-10 days</p>
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Duration of positivity depends on cross reactivity of metabolite norpropoxyphene</p>
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<span style="color:#ff0000;">(***)Values are after typical use; values in parentheses are after heavy or prolonged use.</span></p>
<fieldset><legend>References</legend>
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Adapted from Goldfrank's Toxicologic Emergencies, 9th ed; Table 6-10.</p>
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