Postmortem regional distribution of morphine in dependent rats

Objective: Morphine concentration measured in postmortem tissues may or may not reflect antemortem concentration. We measured levels of morphine in autopsied tissues to determine whether morphine distribution in morphine-dependent rats is altered after death. Methods: Solid-phase extraction was used to extract morphine from the samples, and morphine levels were measured at 0-96 h postmortem using gas chromatography. Results: The study of the morphine dependent rats showed a significant (P<0.05) increase of morphine concentration in postmortem cardiac blood, liver tissues and kidneys tissues. A significant increase was also observed at 72 h and 96 h postmortem in the brain, while morphine levels in cardiac tissues only increased at 24 h and 96 h postmortem. These changes were associated with an observed pH rapid decrease: pH of cardiac blood dropped from 7.36±0.15 to 6.86±0.09 (P<0.01), pH of liver tissues from 6.98±0.04 to 6.34±0.03 (P<0.05). Conclusion: The postmortem regional distribution of morphine occurs in dependent rats, but different from the change that occurs in acute poisoning rats. The morphine concentration in cardiac blood and tissues tends to increase during the period of 0-96 h postmortem in dependent rats. Morphine concentration increases with pH rapid decrease. The antemortem internal amount of morphine affects its postmortem regional distribution. It appears that several mechanisms are accountable for postmortem morphine distribution. The understanding of the mechanisms and patterns may eventually lead to better choices of samples which may better represent antemortem drug levels.

Comparison of the Concentrations of Lidocaine in Different Body Fluids/Tissues after Subarachnoid Space and Intravenous Administration of a Lethal Dose of Lidocaine

The objective of the study was to compare the concentration of lidocaine in different body fluids/tissues after subarachnoid space and intravenous administrations of a lethal dose of lidocaine.Totally 18 dogs were used in the experiment.Six dogs were given subarachnoid anesthesia,another were given an intravenous injection of a dose of 75 mg/kg weight of lidocaine hydrochloride in 5 min and the last 6 dogs were used as the blank control dogs and given a subarachnoid space injection or a femoral artery injection of the same volume of sodium chloride.As soon as its vital signs disappeared,each dog was dissected and the specimen,such as brain,cerebrospinal fluid(CSF)in lateral ventricle,CSF in subarachnoid space,spinal cord(cervical spinal cord,thoracic spinal cord,lumbar spinal cord,and waist spinal cord),heart,lung,liver,spleen,kidney,bile,urine,heart blood,peripheral blood,muscle in injection location,and muscle in no injection location,were collected for analysis of lidocaine immediately.Analysis was performed with gas chromatography‑mass spectrometry(GC‑MS).From the maximum to the minimum,the order of lidocaine concentration detected in the subarachnoid space‑administered dogs was as follows:CSF in subarachnoid space,waist spinal cord,thoracic spinal cord,CSF in lateral ventricle,lumbar spinal cord,cervical spinal cord,lung,kidney,muscle in injection location,heart,brain,spleen,heart blood,liver,peripheral blood,bile,muscle in no injection location,and urine.The order of lidocaine concentration detected in the intravenously administered dogs was as followed:Kidney,heart,lung,spleen,brain,liver,peripheral blood,bile,heart blood,cervical spinal cord,thoracic spinal cord,muscle in injection location,lumbar spinal cord,muscle in no injection location,CSF in subarachnoid space,urine,and CSF in lateral ventricle.The maximum concentration of lidocaine was detected in the subarachnoid space CSF of subarachnoid space‑administered dead dogs,while in intravenously injected dead dogs,the maximum concentration of lidocaine was detected in the kidney.Our study provides some useful data for the forensic identification of epidural anesthesia accidents to decide the way the lidocaine enters the body.