Published: Journal
of Analytical Toxicology, Volume 24, Number 1, January/February, pp59-65
Cocaine, Cocaine Metabolite, and Ethanol Concentrations in Postmortem
Blood and Vitreous Humor
Shannon Mackey-Bojack, Julie Kloss, and Fred Apple
Hennepin County Medical
Center, Clinical Laboratories, MC 812, 701 Park Avenue South, Minneapolis, Minnesota
55415
The use of postmortem
cocaine and metabolite concentrations is a complex subject. This study was undertaken
to determine (1) the usefulness of vitreous humor as a specimen, compared with
blood, to quantitate cocaine and cocaine metabolites; (2) whether there is a preferential
site of disposition for cocaethylene between vitreous humor and blood; and (3)
if the presence of cocaethylene influences the concentration of benzoylecgonine
in postmortem specimens. Cocaine, benzoylecgonine, and cocaethylene were quantitated
in blood and vitreous humor by gas chromatography–mass spectrometry, and
ethanol was quantitated by gas chromatography in 62 medical examiner cases. No
differences were found between mean concentrations of vitreous cocaine 0.613 mg/L
(standard deviation [SD] 0.994 mg/L), cocaethylene 0.027 mg/L (SD 0.59 mg/L),
and ethanol 0.092 g/dL (SD 0.13 g/dL) compared to blood cocaine 0.489 mg/L (SD
1.204 mg/L), cocaethylene 0.022 mg/L (SD 0.055 mg/L), and ethanol 0.058 g/dL (SD
0.91 g/dL), respectively. However, a statistical difference was found between
mean benzoylecgonine concentrations in vitreous 0.989 mg/L (SD 1.597 mg/L) and
blood 1.941 mg/L (SD 2.912 mg/L) (p = 0.0004). Regression analysis demonstrated
that linear relationships were present between concentrations of vitreous and
blood cocaine (r = 0.854) and benzoylecgonine (r = 0.763). However,
the correlation coefficients were lower for cocaethylene (r = 0.433) and
ethanol (r = 0.343). There were variations between the concentrations of
cocaine and metabolites both in terms of magnitude and also direction of change.
Mean concentrations of benzoylecgonine in blood and vitreous were higher in cases
where ethanol was absent, 2.593 mg/L (SD 3.195 mg/L) and 1.431 mg/L (SD 2.021
mg/L), compared to when ethanol was present, 1.199 mg/L (SD 2.396 mg/L) and 0.469
mg/L (SD 0.553 mg/L). This study demonstrates that vitreous humor may be used
to quantitate cocaine and cocaine metabolites; however, because the concentrations
of cocaethylene in vitreous humor and blood were not well correlated, vitreous
humor may not be a reliable specimen for measuring cocaine and cocaine metabolite
concentrations.
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