{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T21:18:57Z","timestamp":1792444737515,"version":"4.5.0"},"reference-count":17,"publisher":"Oxford University Press (OUP)","issue":"2","license":[{"start":{"date-parts":[[2024,11,20]],"date-time":"2024-11-20T00:00:00Z","timestamp":1732060800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,2,3]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>The increasing prevalence of xylazine in the illicit drug supply is a growing concern for major health consequences in individuals who use fentanyl mixed with xylazine, but limited data are available regarding the pharmacokinetics of xylazine in humans.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Xylazine was quantified in serial remnant plasmas collected from 28 patients starting at the initial patient encounter and continuing for up to 52\u2005h from presentation, using LC-MS\/MS to calculate the terminal half-life for xylazine. Xylazine metabolites were identified by product ion scanning, and multiple reaction monitoring was used to estimate the relative abundance of xylazine metabolites in 74 collected plasma samples.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The median terminal half-life for xylazine was calculated to be 12.0\u2005h (range: 5.9\u201320.8). Oxo-xylazine and sulfone-xylazine metabolites were detected in all plasma specimens that contained xylazine.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The half-life of xylazine in humans is longer than previously observed in animal studies, which furthers the current understanding of the expected duration of effects in individuals who use fentanyl mixed with xylazine and the window of detection. Both oxo-xylazine and sulfone-xylazine appear to circulate in plasma for as long as xylazine.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/clinchem\/hvae163","type":"journal-article","created":{"date-parts":[[2024,10,3]],"date-time":"2024-10-03T23:19:06Z","timestamp":1727997546000},"page":"266-273","source":"Crossref","is-referenced-by-count":25,"title":["Xylazine Pharmacokinetics in Patients Testing Positive for Fentanyl and Xylazine"],"prefix":"10.1093","volume":"71","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1907-9495","authenticated-orcid":false,"given":"Yanchun","family":"Lin","sequence":"first","affiliation":[{"name":"Department of Pathology & Immunology, Washington University School of Medicine , St. Louis, MO ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7169-3850","authenticated-orcid":false,"given":"Christopher W","family":"Farnsworth","sequence":"additional","affiliation":[{"name":"Department of Pathology & Immunology, Washington University School of Medicine , St. Louis, MO ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9204-9685","authenticated-orcid":false,"given":"Vahid","family":"Azimi","sequence":"additional","affiliation":[{"name":"Department of Pathology & Immunology, Washington University School of Medicine , St. Louis, MO ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David B","family":"Liss","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, Washington University School of Medicine , St. Louis, MO ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael E","family":"Mullins","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, Washington University School of Medicine , St. Louis, MO ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-3535-6707","authenticated-orcid":false,"given":"Bridgit O","family":"Crews","sequence":"additional","affiliation":[{"name":"Department of Pathology & Immunology, Washington University School of Medicine , St. Louis, MO ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2024,11,20]]},"reference":[{"key":"2025020317210027300_hvae163-B1","doi-asserted-by":"crossref","first-page":"290","DOI":"10.1016\/j.drugalcdep.2008.03.005","article-title":"GC-MS confirmation of xylazine (Rompun), a veterinary sedative, in exchanged needles","volume":"96","author":"Rodr\u00edguez","year":"2008","journal-title":"Drug Alcohol Depend"},{"key":"2025020317210027300_hvae163-B2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.forsciint.2014.03.015","article-title":"Xylazine intoxication in humans and its importance as an emerging adulterant in abused drugs: a comprehensive review of the literature","volume":"240","author":"Ruiz-Col\u00f3n","year":"2014","journal-title":"Forensic Sci Int"},{"key":"2025020317210027300_hvae163-B3","doi-asserted-by":"crossref","DOI":"10.15620\/cdc:129519","volume-title":"Drug overdose deaths involving xylazine, United States, 2018\u20132021","author":"Spencer","year":"2023"},{"key":"2025020317210027300_hvae163-B4","doi-asserted-by":"crossref","first-page":"721","DOI":"10.15585\/mmwr.mm7226a4","article-title":"Illicitly manufactured fentanyl\u2013involved overdose deaths with detected xylazine\u2014United States, January 2019\u2013June 2022","volume":"72","author":"Kariisa","year":"2023","journal-title":"MMWR Morb Mortal Wkly 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(Phila)"},{"key":"2025020317210027300_hvae163-B11","doi-asserted-by":"crossref","first-page":"911","DOI":"10.1093\/jat\/bkac049","article-title":"Xylazine: pharmacology review and prevalence and drug combinations in forensic toxicology casework","volume":"46","author":"Kacinko","year":"2022","journal-title":"J Anal Toxicol"},{"key":"2025020317210027300_hvae163-B12","doi-asserted-by":"crossref","first-page":"452","DOI":"10.1093\/jat\/bkt054","article-title":"Scientific Working Group for Forensic Toxicology (SWGTOX) standard practices for method validation in forensic toxicology","volume":"37","author":"Scientific Working Group for Forensic Toxicology","year":"2013","journal-title":"J Anal Toxicol"},{"key":"2025020317210027300_hvae163-B13","volume-title":"Liquid chromatography-mass spectrometry methods. 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