Dent versus mèche de cheveux. Quelle matrice utiliser pour documenter une exposition répétée ? À propos d’un cas impliquant l’aripiprazole

Abstract

In recent years, remarkable advances in sensitive analytical techniques have enabled the analysis of drugs in unconventional biological specimens such as oral fluid, sweat or hair. However, other matrices, including tooth, deserve attention as they can be the unique remain on a crime scene. The authors present here the comparison between tooth and hair specimens collected from a long-term subject under aripiprazole therapy (5 mg per day). Tooth was collected during a standard consultation for removal of wisdom tooth. At the same time, after oral consent, a strand of hair (blonde in colour) was collected from a 19-year-old man. After careful elimination of organic material, the tooth was pulverized in a ball mill and 20 mg were incubated under alkaline conditions (pH 8.4) followed by a mixture of organic solvents. After decontamination by dichloromethane, the hair was segmented, cut into very small segments (< 1 mm), overnight incubated in buffer and 20 mg were extracted by a mixture of organic solvents. Drugs were tested by LC/MS-MS. Aripiprazole was identified by 2 ion transitions (m/z 450.2 > 287.1 and 450.2 > 98.0). Aripiprazole was identified in the tooth at 1.4 pg/mg. The drug tested also positive in the 3 x 3 cm segments, at 3.5, 3.9 and 2.6 ng/mg. The concentrations of aripiprazole in the hair segments were in a 1000-fold magnitude when compared to what was measured in the tooth. Although there is an interest to test for drugs in tooth when this element is the unique remain of a cadaver, this approach cannot overrule the interest of hair to document long-term drug exposure. Tooth preparation is tedious and the measured concentration is close to the limit of quantitation. In addition, the window of drug detection in tooth remains unknown at this time.