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.

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.