Moriya F, Hashimoto Y
Department of Legal Medicine, Kochi Medical School, Nankoku City, Japan.
J Forensic Sci. 1996 Jul;41(4):612-6.
A study was conducted to examine the postmortem stability of cocaine and cocaethylene in rabbit blood and tissues, and to determine whether cocaethylene is produced in decomposed human specimens containing cocaine and endogenous ethanol. Heart blood, liver, brain and femoral muscle taken from rabbits 20 min after oral administration of 20 mg/kg cocaine together with 2 g/kg ethanol were kept at 20-25 degrees C for 5 days. Cocaine and cocaethylene concentrations were in the order brain > liver > muscle > blood, and showed very large intersubject variations at the time of death. Cocaine was degraded rapidly in the blood and liver. However, 12.0 +/- 8.5% and 26.2% +/- 19.4% of the original cocaine was still detectable in the brain and muscle, respectively. Cocaethylene was degraded more slowly than cocaine in all of the specimens. The pH of the blood remained around 7.4 during a 5-day period; all the other specimens showed pH values of 6.2-6.7 on and after the first day postmortem. When 10,000 ng/g cocaine was incubated with decomposed human blood, liver, brain and muscle homogenates containing 0.29-0.60 mg/g endogenous ethanol at 20-25 degrees C and 37 degrees C, no change in cocaine concentration was observed during the study period of 24 h, and no cocaethylene was detected. The pH values of the homogenates were within the range 4.2 to 5.2 at the beginning of the experiment. It was found that: 1) cocaethylene was more stable in postmortem specimens than cocaine; 2) muscle as well as brain was specimen of choice for detecting cocaine and cocaethylene postmortem; 3) cocaine was resistant to decomposition under acidic conditions; and 4) putrefactive bacteria had no ability to produce cocaethylene even in the presence of cocaine and endogenous ethanol.
开展了一项研究，以检测可卡因和可口卡因在兔血及组织中的死后稳定性，并确定在含有可卡因和内源性乙醇的腐败人体标本中是否会产生可口卡因。给兔子口服20mg/kg可卡因及2g/kg乙醇20分钟后，采集其心脏血液、肝脏、大脑和股肌，并在20-25摄氏度下保存5天。可卡因和可口卡因浓度顺序为脑＞肝＞肌肉＞血液，且死亡时个体间差异极大。可卡因在血液和肝脏中迅速降解。然而，在大脑和肌肉中仍分别可检测到12.0±8.5%和26.2%±19.4%的初始可卡因。在所有标本中，可口卡因的降解速度比可卡因慢。血液pH值在5天内保持在7.4左右；所有其他标本在死后第一天及之后pH值为6.2-6.7。当10,000ng/g可卡因与含有0.29-0.60mg/g内源性乙醇的腐败人体血液、肝脏、大脑和肌肉匀浆在20-25摄氏度和37摄氏度下孵育时，在24小时的研究期间未观察到可卡因浓度变化，且未检测到可口卡因。实验开始时匀浆的pH值在4.2至5.2范围内。研究发现：1）可口卡因在死后标本中比可卡因更稳定；2）肌肉和大脑是死后检测可卡因和可口卡因的首选标本；3）可卡因在酸性条件下抗分解；4）即使存在可卡因和内源性乙醇，腐败细菌也无能力产生可口卡因。
