Distribution profiles of diphenhydramine and lidocaine in scalp, axillary, and pubic hairs measured by micro-segmental hair analysis: good indicator for discrimination between administration and external contamination of the drugs

Purpose Drug distribution in scalp hair can provide historical information about drug use, such as the date and frequency of drug ingestion. We previously developed micro-segmental hair analysis, which visualizes drug distribution at 0.4-mm intervals in individual hairs. The present study examines whether the distribution profiles of drugs can be markers for the administration or external contamination of the drugs using scalp, axillary, and pubic hairs. Methods A single dose of anti-itch ointment containing diphenhydramine (DP) and lidocaine (LD) was topically applied to the axillary or pubic areas of two volunteers; DP was also orally administered; and LD was intra-gingivally injected. Scalp, axillary, and pubic hairs were assessed using our micro-segmental analysis. Results The localization of DP and LD differed within individual scalp hair strands, implying DP and LD were predominantly incorporated into scalp hair via the bloodstream and via sweat/sebum, respectively, showing double-peak profiles. However, DP and LD were distributed along the shafts of axillary and pubic hairs without appearance of the double-peak profiles when the ointment had been applied to the axillary and pubic areas. The distributions of DP and LD in scalp hairs did not significantly differ according to administration routes, such as oral administration, gingival injection, and topical application. Conclusions Micro-segmental analysis revealed differences in the distribution profiles of drugs in hairs, and distinguished hairs with and without external contamination. These findings will be useful for understanding of the mechanism of drug uptake into hair and for estimating the circumstances for a drug use.

Segmental Analysis of R/S-Methamphetamine and R/S-Amphetamine in Abusers’ Head Hair

In this study, the relationships between the concentrations of R/S-methamphetamine (MA) and its metabolite R/S-amphetamine (AP), the AP/MA ratio in hair samples, and MA dependence were investigated by performing segmental hair analysis in MA users. Authentic hair samples collected from 10 chronic MA abusers were cut into 1-cm sections (a total of 120 segments). The concentrations of MA and AM enantiomers were quantitatively measured by the LC–MS-MS method. The S-MA concentrations ranged from 1.17 to 256.41 ng/mg and the S-AP concentrations ranged from 0.11 to 23.31 ng/mg in the 120 segments. S-MA and S-AP were the most common analytes identified in hair; no R-MA or R-AP was found. The S-AP/S-MA ratios ranged from 0.03 to 0.32, indicating that the subjects primarily consumed S-MA rather than R-MA or AP. The S-AP/S-MA ratios in the long hair of all chronic MA abusers showed some variation, but there was an overall trend of gradual increase from the distal to the proximal end. This trend was independent of the drug concentrations. Therefore, we could conclude that the AP/MA ratios increased with the duration of MA abuse, and a higher AP/MA ratio suggested high MA dependence. There was no chiral conversion of MA or AP in the hair matrix. The segmental hair analysis showed that all subjects continuously used S-MA, and some users showed an increase in drug dose or the frequency of use.

Accurate Estimation of Drug Intake Day by Microsegmental Analysis of a Strand of Hair by Use of Internal Temporal Markers

Background Segmental hair analysis can be useful for estimating the time of drug intake. However, this estimation is currently only accurate to within several months. We previously conducted microsegmental analysis of a strand of hair to visualize drug distribution at a spatial resolution of 0.4 mm, which corresponds to daily hair-growth length. Herein, we describe a procedure for accurately estimating the day of drug intake by using internal temporal markers (ITMs) to mark a timescale in the analyzed strand of hair. Methods Five drugs were administered in a single dose to the subjects, and then administration was stopped for several weeks. Two subsequent cycles of drug administration and similar withdrawal were performed. For analysis, a strand of hair was plucked from the subject's scalp. The first intake day was considered as the unknown and the drugs administered second and third were regarded as the ITMs. The first intake day was estimated based on the distance from hair root end to 3 drug peaks and 3 known days (hair sampling and 2 ITM cycles). Results The drug concentration–hair segment curve had 3 peaks, which reflected the 3 drug cycles. The use of ITMs reduced the error of the true intake day to within 2 days, because the growth rate of the analyzed strand of hair was accounted for by the 2 ITMs. Conclusions The estimated accuracy showed little dependency on drug and individual variation. This procedure for estimating the time of drug intake down to a particular day can be used in drug-related crimes, drug abuse and compliance, and for medical diagnosis.