{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,12]],"date-time":"2026-01-12T21:51:35Z","timestamp":1768254695364,"version":"3.49.0"},"reference-count":21,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2022,11,30]],"date-time":"2022-11-30T00:00:00Z","timestamp":1669766400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>(1) Background: Methadone, along with buprenorphine, is the most commonly used drug for the treatment of opioid dependence. This study aimed to analyze methadone and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenyl pyrrolidine (EDDP), in the urine and plasma of opiate addicts. The study group consisted of drug users voluntarily admitted to the detoxification center C.E.T.T.T. \u201cSt. Stelian\u201d of Bucharest. Secondly, the study aimed to identify whether urine or plasma provides better results for the proposed method. (2) Methods: A GC-MS method, using an internal standard (diphenylamine) in the FULL-SCAN and SIM modes of operation and using the m\/z = 72 ion for methadone and the m\/z = 277 ion for EDDP, combined with a liquid\u2013liquid extraction procedure was performed. (3) Results: The applied procedure allows the detection and quantification of methadone in both urine and plasma samples. EDDP was identified in patients with higher levels of methadone. Higher levels of methadone were detected in urine than in plasma samples. (4) Conclusions: This procedure can be used in clinical laboratories for the rapid determination of methadone levels in urine rather than in plasma. The procedure can be applied for the monitoring of methadone substitution treatment.<\/jats:p>","DOI":"10.3390\/molecules27238360","type":"journal-article","created":{"date-parts":[[2022,11,30]],"date-time":"2022-11-30T08:46:41Z","timestamp":1669798001000},"page":"8360","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["GC-MS Analysis of Methadone and EDDP in Addicted Patients under Methadone Substitution Treatment: Comparison of Urine and Plasma as Biological Samples"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3237-8318","authenticated-orcid":false,"given":"Daniela-M\u0103d\u0103lina","family":"Ciuc\u0103 Anghel","sequence":"first","affiliation":[{"name":"Department of Toxicology, Carol Davila University of Medicine and Pharmacy, 37 Dionisie Lupu Street, Sector 2, 20021 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anne-Marie","family":"Ciobanu","sequence":"additional","affiliation":[{"name":"Department of Medicines Control, Carol Davila University of Medicine and Pharmacy, 37 Dionisie Lupu Street, Sector 2, 20021 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Claudia Maria","family":"Gu\u021bu","sequence":"additional","affiliation":[{"name":"Department of Toxicology, Carol Davila University of Medicine and Pharmacy, 37 Dionisie Lupu Street, Sector 2, 20021 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Miriana","family":"Stan","sequence":"additional","affiliation":[{"name":"Department of Toxicology, Carol Davila University of Medicine and Pharmacy, 37 Dionisie Lupu Street, Sector 2, 20021 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gheorghe","family":"Tudor","sequence":"additional","affiliation":[{"name":"Department of Systematic Theology and Sacred Art, Orthodox Theology\u2014Social Work Section, \u201cJustinian the Patriarch\u201d University of Theology, 29 Berzei Street, Sector 1, 010521 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daniela Luiza","family":"Baconi","sequence":"additional","affiliation":[{"name":"Department of Toxicology, Carol Davila University of Medicine and Pharmacy, 37 Dionisie Lupu Street, Sector 2, 20021 Bucharest, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1136\/ewjm.172.1.43","article-title":"Use of methadone","volume":"172","author":"Anderson","year":"2000","journal-title":"West J. 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