The analgesics, codeine, fentanyl, oxycodone and tramadol frequently occur in postmortem cases and determining their role in the cause of death can be challenging. However, postmortem blood is susceptible to redistribution and may not be available in cases of severe blood loss, putrefaction or burns. Brain tissue may serve as a viable supplement to blood or on its own, as it is resistant to postmortem redistribution and often available as a sample matrix when blood is not. We present brain and blood concentrations and brain-blood ratios of the four analgesics from 210 autopsy cases. The cases were classified according to the presumed cause of death: A: The compound was believed to have solely caused a fatal intoxication. B: The compound was assumed to have contributed to a fatal outcome in combination with other drugs, alcohol or disease. C: The compound was not regarded as being related to the cause of death. Blood and brain samples were prepared by automatic solid phase extraction and quantified by liquid chromatography-mass spectrometry. The squared correlation coefficients between concentrations in brain tissue and blood ranged 0.45-0.91. The median brain-blood ratios were codeine 1.8 (range 0.47-4.6), fentanyl 2.1 (range 0.29-16), oxycodone 1.8 (range 0.11-6.0), and tramadol 1.8 (range 0.047-6.8). A significantly higher brain-blood ratio of codeine was observed in cases where heroin had been administered, although there was a wide overlap. Intravenous and transdermal fentanyl administration could not be distinguished based on the blood or brain concentration or the brain-blood ratio. The results of this study may benefit the toxicological investigation in postmortem cases where one of the four analgesics are suspected of having contributed to or caused a fatal intoxication.

中文翻译：

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可待因，芬太尼，羟考酮和曲马多的死后脑血比。

在死后病例中经常使用止痛药，可待因，芬太尼，羟考酮和曲马多，要确定它们在死亡原因中的作用可能是具有挑战性的。但是，验尸后的血液易于重新分配，在严重失血，腐败或烧伤的情况下可能无法使用。脑组织可以作为血液的可行补充剂，也可以单独使用，因为它对事后再分配具有抵抗力，在没有血液的情况下通常可以作为样本基质。我们介绍了210例尸检病例中四种止痛药的脑血浓度和脑血比。根据推测的死亡原因对病例进行分类：答：据信该化合物仅引起致命的中毒。B：假定该化合物与其他药物，酒精或疾病联合使用可导致致命的后果。C：该化合物不被认为与死亡原因有关。通过自动固相萃取制备血液和脑样品，并通过液相色谱-质谱法进行定量。脑组织和血液中浓度之间的平方相关系数在0.45-0.91之间。中位数脑血比为可待因1.8（范围0.47-4.6），芬太尼2.1（范围0.29-16），羟考酮1.8（范围0.11-6.0）和曲马多1.8（范围0.047-6.8）。尽管服用海洛因的情况存在很大的重叠，但观察到可待因的脑血比例明显较高。静脉和透皮芬太尼给药不能根据血液或脑部浓度或脑血比例来区分。