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

Abstract

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.

Single hair analysis: Validation of a screening method for over 150 analytes and application on documented single‐dose cases

“…Ideally, the average individual hair growth rate should be applied but is usually not known. Kuwayama et al 25 used a so‐called “internal temporal marker” by ingestion of a known substance at defined time points after a suspected drug intake thus enabling to calculate the time point of administration based on the individual (single) hair growth rate, deduced from the position of the marker within the hair shaft. In our study, a different approach has been used without the need to ingest a further substance.…”

“…Ideally, the average individual hair growth rate should be applied but is usually not known. Kuwayama et al25 used a so-called "internal temporal marker" by ingestion of a known…”

Development of an improved method to estimate the days of continuous drug ingestion, based on the micro‐segmental hair analysis

“…The accuracy was almost the same as that in single-dose ingestion, as we previously reported. 12 The absolute average error and its variation for estimating the number of days (Y at Scene 1) were smaller (1.5 ± 1.4 days) than those for X, because Y is independent of the distance between the peaks of ITM and a targeted drug.…”

“…In our previous reports [10][11][12][13] and preliminary study, we obtained typical drug distribution curves, as shown in Figure 1. When a singledose drug is ingested, the distribution curve has a major peak derived from drug incorporation via the bloodstream (Figure 1B).…”

Microsegmental Analysis of a Single Hair Strand: Pushing the Envelope on Hair Drug Testing

“…MALDI mass spectrometric imaging requires less sample preparation but is less sensitive than LC/MS/MS. Kuwayama et al (1,11), in what they call microsegmental analysis, used 0.4-mm segments of hair. This length of hair approximately corresponds to the average daily growth of human scalp hair.…”