Category: Toxicology
Keywords: Drug Screens, Drug Intervals (PubMed Search)
Posted: 2/5/2015 by Kishan Kapadia, DO
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| Performance Characteristics of Common Drug Abuse Screening Immunoassays | ||
| Drug/Class | Detection Interval (***) | Comments |
| Amphetamines | 1-2 days (2-4 days) | Decongestants, ephedrine,l-methamphetamine, selegilene & bupropion metabolites may give False (+) results; MDA & MDMA are variably detected |
| Barbiturates | 2-4 days | Phenobarbital may be detected for up to 4 weeks |
| Benzodiazepines | 1-30 days | Benzos vary in reactivityand potency; False (+) results may be seen with oxaprozin |
| Cannabinoids | 1-3 days (>1 month) | Screening assays detect inactive and active cannabinoids; Confirmatory assays detects inactive metabolite THCA (tetrahydrocannabinoic acid) |
| Cocaine | 2 days (1 week) | Screening & confirmatory assays detect inactive metabolite BE (benzoylecgonine); False (+) results are unlikely |
| Opiates | 1-2 days; 2-4 days (<1 week) | 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 |
| Methadone | 1-4 days | Doxylamine may cross-react |
| Phencyclidine | 4-7 days (>1 month) | Dextromethorphan, diphenhydramine, ketamine, & venlafaxine may cross react |
| Propoxyphene | 3-10 days | Duration of positivity depends on cross reactivity of metabolite norpropoxyphene |
(***)Values are after typical use; values in parentheses are after heavy or prolonged use.
Adapted from Goldfrank's Toxicologic Emergencies, 9th ed; Table 6-10.
