La diagnosi chimico-tossicologica di esposizione a sostanze d'abuso mediante analisi dei capelli

Owing to the necessity to overcome the time limits of conventional biological substrates (blood and urine), hair analysis is increasingly being used as an efficient analytical tool to ascertain remote and habitual exposure to drugs of abuse. As a matter of fact, hair analysis allows a significant widening of the detection time-window (weeks/months instead of hours/days in the case of blood and urine), thus representing a useful complementary diagnostic tool to the analysis of conventional matrices. Moreover, through segmental analysis, it is possible to get information even on the history of use of a substance. Despite the several methodological as well as practical advantages (easy collection and storage) a number of issues on hair analysis still remain open. Among these, the possibility of removal of incorporated substances after strong cosmetic treatments, passive contamination, the strong method-dependence of analytical results and, most of all, the dependence of results on the sample preparation procedure, should be counted. The aim of this thesis was to tackle some of these issues and, in particular: (a) the removal of drugs of abuse - opiates and cocaine – and of a marker of chronic alcohol abuse, ethyl glucuronide (EtG), from hair as a consequence of two different treatments (with an anti hair loss solution containing Minoxidil and with a strong bleaching lotion); (b) the development and validation of a specific method for the quantification of buprenorphine (BPR) and its metabolite nor-buprenorphine (norBPR) and (c) the definition, through the elaboration of data on hair analysis for driving license renewal/re-issue collected during over 10 years by the Laboratory of Chemical-Toxicological Analysis of the University of Pavia, of an efficient diagnostic-interpretative strategy, with specific reference to the segmental hair analysis. The experimental studies carried out during this thesis permitted to ascertain that: the anti hair loss lotions, containing minoxidil, interfere with hair analysis thus preventing the identification of cocaine and its metabolites, although the problem can be partially solved by adopting a modification in the analytical procedure (omission of the derivatization step); hair bleaching quantitatively removes both opiates and EtG from the hair matrix, whereas for cocaine and metabolites the removal is generally not quantitative; BPR and norBPR are detectable in subjects under BPR treatment (2-8 mg/day), although the concentrations found are low (from 0.01 to 0.1 ng/mg for BPR), thus requiring a highly sensitive analytical method for their detection; the elaboration of data collected in the period 1996-2007 highlighted an increasing demand of hair analyses (quadruplication of the number of requests per year), an increasing trend of cocainepositive cases accompanied by a decreasing trend in opiate-positive cases, and the dependence of results (positive/negative) on the type of request: either segmental hair analysis (analysis of the two 3-cm proximal and distal segments, as suggested in the Guidelines on hair analysis for drugs of abuse issued by Lombardy) rather than the analysis of the whole 6-cm segment, likely due to a dilution effect in the latter case.