Degradation of Bupropion: Implications for Interpretation of Postmortem Case Data.

The interpretation of postmortem bupropion is often a challenge to the forensic toxicology community because of the instability of the parent compound. At the North Carolina Office of the Chief Medical Examiner (NC OCME) toxicology laboratory, one of the active metabolites, threobupropion, is used as a complementary indicator for the extent of exposure to the parent compound. Metabolite data will address postmortem normal concentrations as well as when bupropion was attributed to the cause of death. For 55 natural cases where bupropion was unattributed to the cause of death, the blood and liver mean threobupropion concentrations were 1.8 mg/L and 12.1 mg/kg, respectively, with median concentrations of 1.5 mg/L and 10 mg/kg, respectively. For the 51 suicidal ingestion cases when bupropion was attributed to the cause of death, the blood and liver mean threobupropion concentrations were 15.8 mg/L and 131.5 mg/kg, respectively, with median concentrations of 13.5 mg/L and 110 mg/kg, respectively. The laboratory completed a stability study over the course of 50 days to evaluate how bupropion and threobupropion degrade in postmortem blood, liver and liver homogenate. The samples were subjected to forensically relevant conditions by storing them at room temperature (RT, 20°C), refrigerated (4°C) and frozen (-20°C). While the concentration of bupropion decreased in all specimens, the rate of degradation of the RT samples was the most dramatic. The threobupropion metabolite appeared to be relatively stable. The postmortem case data along with the evaluation of potential degradation products should provide an overall picture to assist the toxicological community with the interpretation of bupropion found in routine casework.

Postmortem Metaxalone (Skelaxin®) Data from North Carolina.

The North Carolina Office of the Chief Medical Examiner Toxicology Laboratory identified 61 cases from 2002 to 2014 where metaxalone was detected during routine postmortem drug screening in support of a determination of cause and manner of death. Decedents were divided into groups based on the manner of death with the goal of studying metaxalone concentrations in overdose and non-overdose situations (natural, accident, suicide and undetermined). Subgroups were established for cases in which metaxalone contributed to the cause of death (attributed) and cases in which it did not (unattributed). Attributed cases were divided into those where metaxalone additively combined with other drugs and cases in which the drug was present in sufficient amounts to be the primary cause of death, regardless of other drugs present and the concentrations of those drugs. The mean metaxalone concentration for the additive deaths was 14.2 mg/L with a median value of 11 mg/L (n = 18) and a mean metaxalone concentration of 36.7 mg/L with a median value of 32 mg/L (n = 9) for primary deaths. For unattributed metaxalone concentrations, the mean was 3.4 mg/L with a median value of 2.9 mg/L (n = 31). Of the 61 cases, 34% fall at or below a therapeutic concentration of ≤4 mg/L. The selected case studies offer valuable information regarding postmortem interpretation.