Unexpected Variation of the Codeine/Morphine Ratio Following Fatal Heroin Overdose

Postmortem samples from 14 cases of suspected heroin overdosewere subjected to a preliminary systematic toxicological analysis inorder to highlight the presence of unknown exogenous compounds(e.g., drugs of abuse, alcohol) that may have played a role in themechanism of death. This analysis unveiled histories of poly-druguse in seven of the cases under investigation. Moreover, the concentrationsof morphine and codeine in the brain were also investigated,and the results were compared with the data obtained from the bloodspecimens. The concentration of morphine in blood ranged from 33 to688 ng/mL, while the concentration of codeine ranged from 0 to193 ng/mL. However, in the brain, the concentration of morphinewas found to be between 85 and 396 ng/g, while the levels of codeineranged from 11 to 160 ng/g. The codeine/morphine ratio inthe blood ranged from 0.043 to 0.619; however, in the brain, thesame ratio was found to be between 0.129 and 0.552. In mostcases, a significantly higher codeine/morphine ratio was found inthe brain, suggesting the accumulation of codeine in brain tissuedue its high lipophilicity as compared with morphine.