Analytical Methods for the Quantification of Drugs and Their Metabolites in Human Hair: A Systematic Review From 2010 to 2025.

Hair has emerged as a valuable biological matrix for documenting long-term or cumulative drug exposure. Although hair analysis is well established in forensic toxicology, its potential application to monitor occupational exposure to hazardous drugs among healthcare workers remains unexplored. This systematic review aimed to describe analytical methods used for drug quantification in human hair and to assess the feasibility of applying this approach to hazardous drug exposure monitoring. A systematic search of PubMed, Embase, and CINAHL was conducted for studies published between January 2010 and March 2025 using the terms hair, matrix, drug, and analysis. Eligible studies reported quantitative measurements of drugs or metabolites in human hair. Data on study characteristics, analytical methods, and results (LOD, LOQ, concentration range in ng/mg) were extracted and descriptively analyzed. One hundred thirteen studies were included, mainly from Europe, most addressing forensic toxicology (77/113). The vertex posterior region was the preferred sampling site. Liquid-liquid extraction (LLE) with methanol and LC-MS/MS were the predominant analytical approaches, providing the lowest LODs and LOQs. A total of 233 analytes (152 drugs and 81 metabolites) were identified, mainly antidepressants, opioids, and antipsychotics. Only one study assessed a hazardous drug (soluble platinum compounds): Exposed workers showed median platinum levels of 3.24 versus 2.17 pg/mg in unexposed staff and 213 pg/mg in treated patients. Hair analysis is a promising, noninvasive approach for documenting long-term exposure to drugs. However, further studies are needed to validate its use for occupational biomonitoring of hazardous drugs in healthcare settings.