Help me interpret this postmortem toxicology report
August 22, 2009 9:15 PM   Subscribe

Toxicology experts: Please help me interpret this postmortem toxicology report. The report, and my questions, are inside.


Cocaine Metabolite -- POSITIVE
Benzoylecgonine -- POSITIVE -- 1350 ng/mL*
Parent Cocaine -- NONE DETECTED
Eogonine Methyl Ester -- POSITIVE -- 165 ng/mL**
Cocaethylene -- NONE DETECTED

* Reporting threshold: 50 ng/mL
** Reporting threshold: 10 ng/mL

My main questions:

(1) Can you tell from these results how recently the deceased had used cocaine?
(2) Is there anything in these results that would indicate how much cocaine the person had used?
(3) Is there anything in these results that would indicate what form of cocaine the person had used (crack or powder)?
(4) What does "parent cocaine" and "cocaethylene" signify in this toxicology report, and what is the significance of the "none detected" for these substances?
(5) Is there anything else significant or interesting about this report?

Thanks for your help!
posted by jayder to Science & Nature (7 answers total) 5 users marked this as a favorite
Response by poster: The specimen type is "peripheral blood"
posted by jayder at 9:17 PM on August 22, 2009

Someone more qualified to answer this will have to give you the definitive answers to most of that but I can help with some of it.

"Parent cocaine" means testing for cocaine directly rather than looking for its metabolites (the stuff made as it is broken down in the liver). Benzoylecgonine and ecgonine (not, I believe, eogonine) methyl ester are metabolites made by the body when the liver breaks down cocaine. Cocaetyhlene is a metabolite made when cocaine and alcohol are metabolized together.

So that would indicate that cocaine was ingested at some point but not taken concurrently with alcohol because if taken with alcohol there would be cocaethylene in addition to the other metabolites.

Someone else would have to tell you how they tell the quantity ingested and the timeline. Obviously there has to be a differentiation between a larger quantity taken longer ago and a smaller quantity taken more recently. Whether that is possible and how accurate it is I have no idea.

My very strong suspicion in response to your #3 is that there is not. Crack and cocaine are essentially the same thing. It's like the difference between snorting an amphetamine or taking it orally; it affects how rapidly it gets into your bloodstream but once there it acts the same.
posted by Justinian at 10:00 PM on August 22, 2009

My very strong suspicion in response to your #3 is that there is not. Crack and cocaine are essentially the same thing.

Just an aside: I do remember reading a paper which compared the metabolite profiles of oral and injected cocaine, and the latter showed the presence of norcocaine, absent in the former. So my guess is it may be possible.
posted by daksya at 10:49 PM on August 22, 2009

Justinian nails (4).

I believe ecgonine methyl ester is the same thing as methylecgonidine, which is only formed when freebase cocaine is smoked. The presence of ecgonidine methyl ester therefore tells you that the form used was crack. Aside from pyrolysis, I'm skeptical that variations in administration method will result in demonstrable differences in metabolite profile.

If the tox report gave bloodlevels of ecgonidine, a metabolite of methylecgonidine, you could use the relative amounts to estimate the time since administration, but it doesn't seem to be included.

Since benzoylecgonine is the primary metabolite of cocaine, you know that at least 1350 ng/mL of cocaine have been through the bloodstream. Humans have about 5 L of blood, so that gives you an approximate amount of 6.75 g. The actual amount is probably more, because 1) not all of the benzoylecgonine will necessarily be in the bloodstream, and 2) there are other metabolites of cocaine.

If you knew the sensitivity of the assay used, you could use that along with the half-life of cocaine to calculate the approximate number of hours since administration, based on the amount consumed given above. But when you're calculating estimations based on estimations, the result's going to be pretty fuzzy.
posted by dephlogisticated at 5:05 AM on August 23, 2009

Bah! Shame on me, I forgot to convert to moles. 1350 ng/mL would be the product of 7.08 g of cocaine, not 6.75 g.
posted by dephlogisticated at 8:20 AM on August 23, 2009

Response by poster: Thank you very much for these responses so far. Very helpful!
posted by jayder at 8:59 AM on August 23, 2009

Thanks, dephlogisticated. I had no idea that methylecgonidine was only formed when cocaine was smoked!
posted by Justinian at 11:45 AM on August 23, 2009

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