Evaluation of Therapeutic Opioids in Skin‐Derived Matrices (Sweat and Sebum) of Neonatal and Pediatric Patients and Their Role in Opioid Incorporation Into Hair

Hair analysis is a valuable tool in forensic toxicology to assess opioid exposure in both adult and pediatric populations. However, interpretation of analysis results is challenged by the scarcity of reliable reference data on opioids in hair and by the lack of knowledge on involved hair incorporation pathways, e.g., via skin‐derived matrices such as sweat and sebum. In order to address these limitations, we conducted a clinical study in cooperation with the University Children's Hospital Zurich, where we obtained and analyzed hair and skin swab samples of 150 pediatric intensive‐care patients (median age: 53 days). These patients had a treatment history with opioids, including fentanyl, sufentanil, remifentanil, alfentanil, morphine, methadone, and hydromorphone. Most of the substances, as well as selected metabolites, were repeatedly detected in both sample types, exhibiting comparable concentration trends and metabolite‐to‐parent drug ratios. For fentanyl and morphine, a positive correlation was observed between the administered opioid doses and the analyte concentrations in both the hair and skin swab samples. In addition, a correlation was found for fentanyl between concentrations in hair and skin swab samples ( r = 0.356, p = 0.0007), indicating a contribution of skin‐derived matrices to opioid incorporation into the hair of children and neonates. The comprehensive and clinical nature of this study provides unique value for the generated concentration data and associated findings, providing a potential reference source for future interpretation of hair analysis results.