| Drug | Time frame for positive urine assay with acute exposure*
(time frame for chronic exposure in parentheses) | Substance detected | False positives
(false positivity varies by assay) | Comments |
| Amphetamine | - 1 to 2 days (2 to 4 days)
| | - Amphetamine assays have poor specificity due to structural similarity of many drugs, herbal supplements, and medications.
- False positives result from structurally similar substances, drugs that are metabolized to structurally similar molecules in vivo, and structurally dissimilar molecules.
- Nasal decongestants, including l-methamphetamine, phenylephrine, pseudoephedrine; herbal products, including ephedrine, synephrine; amphetamine analogues; medications including bupropion, selegiline, propranolol, atenolol.
| - Many assays include MDMA and methamphetamine, but this varies by manufacturer. Refer to manufacturer's literature.
- Over 100 "designer" amphetamines exist, dozens of which are widely available for purchase on the internet. These may not be detected by routine screening.
- Atomoxetine and methylphenidate are not detected by routine screening.
|
| Benzodiazepines | - 1 to 5 days (most)
- 2 to 30 days for diazepam
- Chronic use does not significantly alter window of detection
| - Oxazepam (most common)
- Various benzodiazepine metabolites
| | - Due to poor sensitivity of assays, not recommended as a urine immunoassay in the emergency setting.
- No single assay is known to detect all benzodiazepines. Depending on metabolites detected, commonly used benzodiazepines such as alprazolam and lorazepam might not be detected.
- "Z" drugs (eszopiclone, zaleplon, zolpidem, zopiclone) are not detected by benzodiazepine screening.
- Detection depends on half-life of metabolites, which is generally several days, but for diazepam and chlordiazepoxide may be >1 week.
|
| Cocaine | | - Benzoylecgonine (cocaine metabolite)
| | - Cocaine assays have high specificity and overall accuracy.
|
| GHB | - <24 hours
- Chronic use does not significantly alter detection
| | - Endogenous neurotransmitter naturally present in minute quantities.
| - Detection is difficult because of brief half-life and technical problems.
- GHB detection is possible but requires specific assay. Congeners GBL and 1,4 butanediol are detected by GHB screening.
- Often included in screening panel for drug-facilitated sexual assault.
|
| Ketamine | | | | - Not detected by routine screening assays, must be ordered as a standalone test.
|
| LSD | | - 2-oxo-3-hydroxyLSD (LSD metabolite)
| | - Not commonly used in clinical settings.
|
| Marijuana | | - 11-nor-9-carboxy-delta9-THC (THC metabolite)
| - Hemp-containing foods.
- Early, rare reports of false positives from NSAIDs associated with assays that are no longer in use.
| - False positive urine testing due to secondhand smoke exposure is considered impossible.
- Consumption of hemp-containing foods is extremely unlikely to cause a positive test. Differentiation between positive tests from marijuana use and hemp oil is generally not possible.
- No longer recommended as a required urine immunoassay due to the extended time frame for a positive test and lack of evidence of relevant acute adverse effects.
- Synthetic cannabinoids that are widely abused are not detected by routine urine assays.
|
| Opioids | | | | - In recognition that poppy seed consumption may cause positive tests, the threshold for detection in urine was substantially raised. Using the recommended threshold, poppy seed consumption is unlikely to cause positive results. However, not all institutions use the recommended threshold.
- Routine opioid screening does not detect synthetic opioids, such as buprenorphine, fentanyl, methadone, meperidine, pentazocine, propoxyphene, tramadol, and loperamide.
- Oxycodone is poorly detected by many routine opioid screening assays. Specific assays are required.
|
| | | - Methadone
- EDDP (methadone metabolite)
| | - Due to problems with noncompliance and diversion, assays detect both methadone and the methadone metabolite EDDP.
- Noncompliant patients who are diverting their methadone to other abusers commonly try to add methadone to their urine samples to demonstrate compliance.
|
| | | - Norpropoxyphene (propoxyphene metabolite)
| | |
| PCP | | | - Dextromethorphan, diphenhydramine, doxylamine, ketamine, tramadol, and venlafaxine
| - Dozens of congeners of PCP with similar clinical effects exist, and these are variably detected or not detected by PCP screening.
- Many causes of false-positive screening exist, and due to the low prevalence of PCP use in most settings, the likelihood of a true positive test is low.
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