A case of a false-positive levorphanol on an LC-QTOF urine drug screen due to the presence of dextromethorphan is described. Levorphanol is a stereoisomer of dextrorphan, the main metabolite of dextromethorphan. Dextromethorphan does not produce the same analgesic and sedative effects as opioids, which exhibit nervous system and respiratory depression. LC-MS assays are not able to distinguish between stereoisomers, and thus dextrorphan in the sample will be recognized as levorphanol. Only enantiomeric chiral LC-MS/MS analysis can help differentiate the two compounds. The primary caregiver was notified that with dextromethorphan present, the detected levorphanol was most likely the metabolite dextrorphan.
|Original language||English (US)|
|Title of host publication||Toxicology Cases for the Clinical and Forensic Laboratory|
|Number of pages||3|
|State||Published - Jan 1 2020|
- LC/Q-TOF mass spectrometry
ASJC Scopus subject areas