{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T16:50:46Z","timestamp":1790095846795,"version":"4.0.1"},"reference-count":49,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2022,2,1]],"date-time":"2022-02-01T00:00:00Z","timestamp":1643673600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["analyticalsciencejournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Drug Testing and Analysis"],"published-print":{"date-parts":[[2022,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Phenyltetrahydroimidazothiazole (PTHIT, tetramisole) is the most frequently used adulterant of cocaine and exists in the two enantiomeric forms levamsiole (S) and dexamisole (R). Existing studies show diverse fractions of samples containing enantiopure levamsiole, levamisole\u2010enriched mixtures, and racemic tetramisole as adulterant. However, blood samples have never been enantioselectively tested for PTHIT. Because enantiomers are usually metabolized stereoselectively, chiral analysis of blood samples can help estimate the time of drug use, provided that a racemic substance is ingested. Therefore, an enantioselective liquid chromatography\u2013tandem mass spectrometry (LC\u2013MS\/MS) method was developed using a chiral column. Validation of the method was carried out for methanolic substance samples as well as serum samples and showed satisfactory selectivity, sensitivity, linearity (0.05\u2013100\u2009ng\/mL), precision, and accuracy; 151 cocaine samples seized in Germany between 2018 and 2021 were analyzed. Most (94%, <jats:italic>n<\/jats:italic>\u2009=\u200948) of the 51 PTHIT\u2010positive samples contained racemic tetramsiole, whereas there were two samples containing levamisole\u2010enriched mixtures and one sample containing nearly enantiopure levamisole. Furthermore, 157 cocaine and\/or benzoylecgonine\u2010positive forensic serum samples were tested with cocaine\u2010positive samples showing the highest frequency of PTHIT detection (43%). All positive samples contained either dexamisole alone or (R)\/(S)\u2010concentration ratios &gt;1 (1.05\u201370.6). Finally, a self\u2010administration study was conducted with three subjects taking 10\u00a0mg of racemic tetramisole each. Although peak concentrations and corresponding times did not differ significantly between the enantiomers, dexamisole showed significantly longer apparent elimination half\u2010lives (7.02\u201310.0\u00a0h) than levamisole (2.87\u20134.77\u2009h). The resulting steadily increasing (R)\/(S)\u2010ratios can therefore be helpful in estimating the time of cocaine consumption.<\/jats:p>","DOI":"10.1002\/dta.3227","type":"journal-article","created":{"date-parts":[[2022,1,20]],"date-time":"2022-01-20T20:50:03Z","timestamp":1642711803000},"page":"1053-1064","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Chiral pharmacokinetics of tetramisole stereoisomers\u2014Enantioselective quantification of levamisole and dexamisole in serum samples from users of adulterated cocaine"],"prefix":"10.1002","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8880-1512","authenticated-orcid":false,"given":"Moritz","family":"Losacker","sequence":"first","affiliation":[{"name":"Department of Forensic Toxicology, Institute of Legal Medicine University Medical Center Mainz  Mainz Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marica","family":"Hundertmark","sequence":"additional","affiliation":[{"name":"Department of Forensic Toxicology, Institute of Legal Medicine University Medical Center Mainz  Mainz Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Siegfried","family":"Z\u00f6rntlein","sequence":"additional","affiliation":[{"name":"Forensic Science Institute, Dez. 33 Chemistry\/Toxicology State Office of Criminal Investigation Rhineland\u2010Palatinate  Mainz Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J\u00f6rg","family":"R\u00f6hrich","sequence":"additional","affiliation":[{"name":"Department of Forensic Toxicology, Institute of Legal Medicine University Medical Center Mainz  Mainz Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8405-4417","authenticated-orcid":false,"given":"Cornelius","family":"Hess","sequence":"additional","affiliation":[{"name":"Department of Forensic Toxicology, Institute of Legal Medicine University Medical Center Mainz  Mainz Germany"},{"name":"Proficiency Testing Department Reference Institute for Bioanalytics  Bonn Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2022,2]]},"reference":[{"issue":"2","key":"e_1_2_6_2_1","first-page":"12","article-title":"The separation of cocaine and phenyltetrahydroimidazothiazole mixtures","volume":"10","author":"Mallette JR","year":"2013","journal-title":"Microgram Journal"},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00204\u2010017\u20101947\u20104"},{"issue":"3","key":"e_1_2_6_4_1","first-page":"134","article-title":"Levamisole: an analytical 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