Quetiapine may cause a false positive for which substance on urine drug screening?

Quetiapine may cause a false positive for which substance on urine drug screening?

• A. Cannabis
• B. Opiates
• C. Methadone
• D. Cocaine

Answer: (C)

Immunoassay urine drug screens work by antibodies that pick up drug classes, not exact chemicals. Some medications can cross-react with those antibodies and cause false positives. Quetiapine, an atypical antipsychotic, and its metabolites can non-specifically cross-react with the methadone screen, leading to a positive result even when methadone isn’t present. Because these screens are preliminary, a positive result for methadone should be confirmed with a more specific test like GC-MS or LC-MS/MS. The other substances listed are not the typical false-positive target for quetiapine in standard immunoassays.

Immunoassay urine drug screens work by antibodies that pick up drug classes, not exact chemicals. Some medications can cross-react with those antibodies and cause false positives. Quetiapine, an atypical antipsychotic, and its metabolites can non-specifically cross-react with the methadone screen, leading to a positive result even when methadone isn’t present. Because these screens are preliminary, a positive result for methadone should be confirmed with a more specific test like GC-MS or LC-MS/MS. The other substances listed are not the typical false-positive target for quetiapine in standard immunoassays.