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Show CHAPTER 1 OVERVIEW Introduction The first published report of the incorporation of xenobiotics into hair occurred in 1858 (1). Since then hair has been used to measure the exposure to heavy metals, vitamins, drugs of abuse, and medications (2-19). The analysis of hair has been used in clinical and research settings, in a forensic setting for postmortem examinations and as an adjunct to workplace urine drug testing programs. Compared to the more traditional biological matrices such as blood and urine, hair may offer a fairly long window of detection of drugs due to its slow growth and the possibly permanent retention of drugs. Weeks to months and perhaps years of drug exposure history may be obtained from hair analysis verses hours to days from blood or urine. It has also been proposed that hair may be used to establish drug use with respect to time based on the location of the drug within the shaft of the hair. However, this can be done only if the factors affecting the incorporation and retention of drugs in hair and the relationship of these factors to hair growth are completely understood. This chapter will provide an introduction to the science and history of drug analysis in hair and the current state of understanding of the incorporation of drugs into hair. The anatomy and physiology of hair will be discussed as well as the chemistry of the pigment melanin which appears to playa major role in the incorporation of certain drugs into hair. This overview will conclude with the objectives of this project and the experimental hypotheses that are the basis for the research performed. |
