biostudies-literatureXie ZAmerican Heart AssociationCenter for Tobacco Products, Department of DefenseNIEHS NIH HHSNHLBI NIH HHSFDA HHSNational Institutes of HealthJewish Heritage Fund for ExcellenceNIH HHSNIGMS NIH HHSFood and Drug Administration320-330https://www.ebi.ac.uk/biostudies/studies/S-EPMC12469198biostudies-literatureUnknown207(2)The emergence of synthetic nicotine analogs in "tobacco-free" products, such as 6-methylnicotine (6MN; aka Metatine) in SPREE BAR, presents new regulatory and public health challenges. Alarmingly, little is known about the metabolism of 6MN, its potential biomarkers of exposure, or its toxicity. In this study, we systematically characterized oxidized metabolites of 6MN in the urine of mice exposed to 6MN (via intraperitoneal or inhalation route) using liquid chromatography-high resolution mass spectrometry. Similarly, human urine samples were analyzed for 6MN metabolites after use of the SPREE BAR (Blue Razz Ice) product. Nine 6MN metabolites were identified in mouse urine, and each metabolite corresponded with a known nicotine metabolite, albeit with increased mass (i.e. m/z + 14 Da). AltToxicological sciences : an official journal of the Society of ToxicologyCharacterizing oxidative metabolites of 6-methylnicotine (6MN; aka Metatine): divergent metabolism from nicotine and identification of urinary biomarkers of exposure.PMC12469198R01 HL149351HL171763P30ES030283HL122676P30 ES030283P30 GM127607P20GM127607R01 HL171763T32ES011564T32 ES011564S10OD026840S10OD032361U54HL120163S10 OD026840R01 HL122676HL149351P42 ES023716P42ES023716U54 HL120163Stowers HXie ZConklin DJGallagher JKeith RJChen JYLorkiewicz PJin LMiller AfalseCharacterizing oxidative metabolites of 6-methylnicotine (6MN; aka Metatine): divergent metabolism from nicotine and identification of urinary biomarkers of exposure.The emergence of synthetic nicotine analogs in "tobacco-free" products, such as 6-methylnicotine (6MN; aka Metatine) in SPREE BAR, presents new regulatory and public health challenges. Alarmingly, little is known about the metabolism of 6MN, its potential biomarkers of exposure, or its toxicity. In this study, we systematically characterized oxidized metabolites of 6MN in the urine of mice exposed to 6MN (via intraperitoneal or inhalation route) using liquid chromatography-high resolution mass spectrometry. Similarly, human urine samples were analyzed for 6MN metabolites after use of the SPREE BAR (Blue Razz Ice) product. Nine 6MN metabolites were identified in mouse urine, and each metabolite corresponded with a known nicotine metabolite, albeit with increased mass (i.e. m/z + 14 Da). Alt2025-01-01T00:00:00Z2025 Oct2026-06-06T20:06:21.14Z2026-06-04T03:14:18ZS-EPMC124691984069039610.1093/toxsci/kfaf107