Ropinirole metabolite mimics a new psychoactive substance (4-HO-MET) in LC-MS/MS
Forensic Science International December 16, 2021 Magdalene Huen-Yin Tang, Hok-Fung Tong, Ka-Chung Wong et al. 3 citations
A metabolite of the medication ropinirole (N-despropyl-ropinirole) can cause a false positive for the new psychoactive substance 4-HO-MET in urine drug screening by liquid chromatography tandem mass spectrometry (LC-MS/MS), a method usually considered highly reliable. The interference occurred because the two compounds share similar chemical structures, which fooled standard computer-aided spectral library matching. Careful manual review of mass spectra and comparison with a reference specimen correctly identified the compound. The finding underscores that scientists and pathologists must consider clinical context and drug history when interpreting toxicology results, and that mass spectra should be checked for relative ion ratios when results are questionable. Understanding drug metabolism is essential for troubleshooting such errors.