Human Hair: An Important Biological Matrix of Interest

Abstract

Human hair can often be useful biological matrix, alternative to the conventional biological matrices such as blood, serum, urine, saliva etc for clinical and toxicological analyses. The objective of this article was to provide comprehensive details regarding the utilization of human hair as an analytical sample of interest. Such details involve presenting information on hair structure, mechanisms of active substances (drugs) incorporation into human hair, its merits as an analytical sample, collection and preparation for analysis, and various analytical techniques that have been used to determine active substances in the hair samples. The methodology used entailed obtaining information from published works in scientific journals, official books as well the internet websites. The results indicate that numerous active substances belonging to various pharmacological classes namely central nervous system analgesics, antidepressants, antipsychotics, anticonvulsants, anti-hypertensives, anti-inflammatory agents, anxiolytics, cannabinoides, sedatives and steroids etc. that have been incorporated into human hair by passive diffusion from the bloodstream into the growing hair cells or through sweat, sebum, and the external environment have been successfully determined. Literature has also revealed that the speed and extent of active substances penetrating black hair are related to the lipid solubility, molecular weight, and polarity of the active substances. In conclusion, the study has shown that human hair is an important biological matrix in clinical and toxicological analyses as well as in nutritional, archaeological and forensic investigations.