Suárez-García, A.Álvarez Freire, IvánBermejo Barrera, Ana MaríaCabarcos Fernández, PamelaTabernero Duque, María Jesús2024-03-062024-03-062023Forensic Science International Volume 352, November 2023, 1118550379-0738http://hdl.handle.net/10347/33004Research on the determination of drugs of abuse in hair has established that drugs can be detected in hair even long after cessation of use. The purpose of this study was to analyze hair samples from chronic opioid users who were beginning a controlled drug cessation program. The study population (n = 15) is involved in a drug rehabilitation program in Santiago de Compostela, Spain. Over a 6-month period, subjects provided hair samples at 2-month intervals, with the first sample collected on the day they began the program. Codeine, morphine, and 6-MAM were analyzed by GC/MS (LOQ = 0.2 ng/mg). Hair tresses were divided into 1 cm segments and analyzed for all analytes 0–1 cm corresponding to the proximal portion to the scalp Following cessation of opioid use, traces of codeine, morphine, and 6-MAM still remained in the newly growing hair segments for a specified period. After 2 months, still 27 % of the users tested positive, and at 4 months, 20 % were positive but only for 6-MAM. However, after 6 months of abstinence, the results were negative for all analytes.eng© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC licensehttp://creativecommons.org/licenses/by-nc/4.0/Abstinence timeOpioidsCessation drug useHair analysisjournal article10.1016/j.forsciint.2023.111855open access