Indications
- May be used as a baseline for patients being considered for trial of opioids for chronic pain
- Regular testing is done for patient on opioid agonist therapy to monitor for adherence, validate patient-reported use, and detect coingested substances like benzodiazepines that may affect safety
Immunoassays
- Immunoassays are cheap and fast, but are subject to cross-reactivity
- Window of detection for most metabolites is 1 to 3 days
- An initial 5-panel IA tests for amphetamines, cocaine, benzodiazepines (though not clonazepam), opiates, and methadone
- Validity is best when the urine temperature is 90 to 100ºF (within 4 minutes of voiding), urine pH 4.5 to 8, and urinary creatinine ≥20 mg/dL (if <5 mg/dL, it's not urine)
Interpretation
| Substance | False positives |
|---|---|
| Alcohol | Short-chain alcohols (e.g. isopropyl alcohol) |
| Amphetamines | Amantadine Benzphetamine Bupropion Chlorpomazine Clobenzorex l-Deprenyl Desipramine Dextroamphetamine Ephedrine Fenproporex Isometheptene Isoxsuprine Labetalol MDMA Methamphetamine Methylphenidate Phentermine Phenylephrine Phenylpropanolamine Protethazine Pseudoephedrine Ranitidine Ritodrine Selegiline Thioridazine Trazodone Trimethobenzamide Trimipramine |
| Benzodiazepines | Oxaprozin Setraline |
| Cannabinoids | Dronabinol Efavirenz Hemp-containing foods NSAIDs Proton pump inhibitors Tolmetin |
| Cocaine | Coca leaf tea Topical anesthetics containing cocaine |
| Opioids, opiates, and heroin | Dextromethorphan Diphenhydramine Heroin Opiates (codeine, hydromorphone, hydrocodone, morphine) Poppy seeds Quinine Quinolones Rifampin Verapamil and metabolites |
| Phencyclidine | Dextromethorphan Diphenhydramine Doxylamine Ibuprofen Imipramine Ketamine Meperidine Mesoridazine Thioridazine Tramadol Venlafaxine and desvenlafaxine |
| TCAs | Carbamazepine Cyclobenzaprine Cyproheptadine Diphenhydramine Hydroxyzine Quetiapine |
