Segmental Hair Analysis after a Single Dose of Zolpidem: Comparison with a Previous Study

Hair is a useful aid and sometimes even the only matrix in the analytical strategy in drug-facilitated crime (DFC) investigations. In this novel study, segmental hair analysis was performed after a single 10 mg dose of zolpidem was given to 20 Chinese volunteers. Hair was collected 1 month after administration and was analyzed using ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry. Zolpidem concentrations were found to be in the range of 135.0-554.6 pg/mg in the proximal 0-2 cm segments. These results were markedly different from those reported by Villain et al., who used volunteers administered equal doses of zolpidem. The analytical method used, as well as the volunteers' hair color, inter-individual variations such as metabolic capacity, hair growth rate, drug incorporation rates, physical state of the hair, age, gender, body weight, etc. and diffusion from sweat or other secretions are all factors that should be considered when interpreting the DFC results.