Postmortem Brain-Blood Ratios of Amphetamine, Cocaine, Ephedrine, MDMA and Methylphenidate

Brain tissue may serve as a useful supplement to blood in postmortem investigations. However, reference concentrations for central stimulant drugs are scarce in brain tissue. This study involves some frequently used stimulants: amphetamine, cocaine, ephedrine, MDMA and methylphenidate. We present concentrations from brain and blood and brain-blood ratios of the analytes from autopsies. The cases were grouped according to the cause of death: A: The compound solely caused a fatal intoxication. B: The compound contributed to a fatal outcome in combination with other drugs, alcohol or disease. C: The compound was not related to the cause of death. Analyses were carried out using solid-phase extraction and ultra high-performance liquid chromatography. Paired brain and femoral blood concentrations from 133 cases were analysed. Positive correlations were observed for all analytes with correlation coefficients ranging from 0.58 to 0.95. The following median brain-blood ratios were obtained: cocaine 2.0 (range 0.20-7.0), amphetamine 3.2 (range 1.5-4.5), ephedrine 2.3 (range 1.1-6.2), MDMA 3.9 (range 0.92-5.1) and methylphenidate 2.4 (0.92-4.6). The concentrations in femoral blood generally agreed with the literature for all compounds. The metabolite of cocaine, benzoylecgonine, was also quantified in brain and blood from 60 cases, and the median brain-blood ratio was 0.66 with 10-90 percentiles of 0.39-1.27. The results of this study can aid the toxicological investigation in determining the cause of death.