Testing for hydroxyzine in human hair after a single controlled administration: First quantitative data

Hydroxyzine is a first-generation antihistamine widely prescribed for its anxiolytic and sedative effects and has been reported in cases of drug-facilitated crimes. To date, no data on hydroxyzine incorporation into human hair after a single intake are available, thus limiting the interpretative value of hair analysis in such contexts. The aim of this study was to provide the first quantitative data on hydroxyzine concentrations in human hair after a single controlled oral administration.

Hair samples were collected from 3 healthy volunteers who received a single 25-mg oral dose of hydroxyzine. One month after administration, the proximal 0-2 cm hair segment was sampled and analyzed. Quantification was performed using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using a Thermo Fisher Scientific Altis + triple quadrupole system.

Hydroxyzine and cetirizine were detected and quantified in all samples. The concentrations of hydroxyzine ranged from 15 to 63 pg/mg, with values of 56 pg/mg and 63 pg/mg in 2 subjects (dark hair) and a lower concentration (15 pg/mg) in the third subject, who had blond hair. Cetirizine was detected at 7-23 pg/mg. These findings demonstrate that hydroxyzine is incorporated in hair at measurable levels after a single intake and highlight the influence of hair pigmentation on its incorporation.

This study provides the first reference data for hydroxyzine concentrations in human hair after the administration of a single dose and supports the relevance of hair analysis as a complementary tool in the retrospective investigation, especially in cases of suspected drug-facilitated crimes, particularly when conventional biological matrices are no longer available.