Analysis of cocaine adulterants in human brain in cases of drug-related death

Abstract

For different reasons, street cocaine is often diluted with pharmacologically active substances, the so-called adulterants such as levamisole or hydroxyzine. A controversial debate exists currently on the uptake of adulterants from cocaine preparations and drug-related death. Previous research convincingly argues that serious adverse side effects that affect the central nervous and cardiovascular systems can be a consequence of adulterated cocaine. AimsHaving identified the presence of adulterants in lung tissue and blood, the concentrations of these substances in brain, an important target location, was of interest. This provides an opportunity to assess their role in cases of drug-related deaths. Materials and methodsWe developed and validated a method for the analysis of cocaine, two cocaine metabolites and six adulterants, which can typically be found in cocaine preparations, and one adulterant metabolite in brain tissue by gas chromatography–mass spectrometry (GC–MS)11Abbreviations: GC–MS, gas chromatography–mass spectrometry; SPE, solid-phase extraction; MSTFA, N-Methyl-N-(trimethylsilyl)trifluoroacetamide; COC, cocaine; BZE, benzoylecgonine; EME, ecgonine methyl ester; DIL, diltiazem; HYD, hydroxyzine; LEV, levamisole; CET, cetirizine; LID, lidocaine; PHE, phenacetin; PRO, procaine; COC-d3, cocaine-d3; BZE-d3, benzoylecgonine-d3; HYD-d8, hydroxyzine-d8; LEV-d5, levamisole-d5; EME-d3, ecgonine methyl ester-d3; SIM, selected ion monitoring; T, target; Q, qualifier ion; GTFCh, German Society of Toxicological and Forensic Chemistry; LoD, limit of detection; LoQ, limit of quantification; ULoQ, upper limit of quantification; RSD, relative standard deviation; ALC, alcohol; COD, codeine; FLU, fluoxetine; IBU, ibuprofen; 6-MAM, 6-monoacetylmorphine; MID, midazolam; MOR, morphine; NOS, noscapine; NRD, nordazepam; NRT, nortilidine; PAR, paracetamol; SIL, sildenafil; TIL, tilidine; THC, tetrahydrocannabinol; ZOP, zopiclone.. Ten brain samples which were tested positive for cocaine were analyzed. The homogenized brain tissue was embedded into drying paper for protein precipitation. During a subsequent solid-phase extraction (SPE), the eluate and one of the wash fractions were collected. After derivatization with N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) in pyridine and isooctane, the extracts were analyzed by GC–MS. Results and discussionThe method was fully validated for cocaine (COC), benzoylecgonine (BZE), ecgonine methyl ester (EME), diltiazem (DIL), hydroxyzine (HYD), and levamisole (LEV) and partly validated for cetirizine (CET), lidocaine (LID), phenacetin (PHE), and procaine (PRO) in brain material. By analyzing post-mortem brain tissue of ten cocaine users, LEV, LID, and HYD as well as PHE were identified in contrast to DIL, PRO, and the HYD metabolite CET. HYD and LEV were found in moderate to high concentrations in some cases. Therefore, it cannot be excluded that they have caused adverse side effects. ConclusionBecause adulterants can potentially affect the central nervous and cardiac systems, it is likely that they enhance COC toxicity.