Recap #cclivechat March 30, 2012

Today’s CCLiveChat centered on postmortem toxicology and pharmacokinetics. Neither topic can be discussed within the hour but we got some good questions in for Peter Mullen!

In general, pharmacokinetics is understanding the “time-course” of a substance in the body or, how fast does it travel through the body? All depends of course on what was taken and in what dosage.

As for misconceptions re postmortem toxicology … people are under the impression that all substances are analyzed for (not true); that insulin is the perfect “murder drug” (not true); and that we have immediate results! As was pointed out in the chat, it can take between 4-6 weeks before there are any results!

No #cclivechat next week during the Easter Weekend, folks. We are back April 13 with a themed chat with Richard Case who will be tweeting about the Finger Print Society Annual Conference!

The verbatim thread is below. If you have any questions, just post them into the comment box and I’ll ask Peter to look at them.

Cheers!

P.S.: Peter wrote an afterword:

Since, due to some glitches and the constraint of time, we never scratched the surface of the complicated subject of postmortem toxicology, I offer this postscript.

In my introductory statements prior to the chat, I stated: “It should be emphasized that the extrapolative utility of pharmacokinetics is limited mostly to the living. Postmortem toxicological applications of pharmacokinetics to estimate antemortem concentrations and amounts are fraught with many possible problems of interpretation due to such phenomena as postmortem redistribution of the substance within the cadaver. The concentration of a xenobiotic in postmortem blood may vary depending on the sampling site, time since death, the physical-chemical nature of the xenobiotic itself, presence (or lack) of preservative in the sampling container, etc.

For those desiring a better appreciation of these and other key issues inherent in interpreting postmortem toxicological findings, including the limitations of pharmacokinetics in this context, I recommend the following articles which are freely available on the web:

“Estimating antemortem drug concentrations from postmortem blood samples: the influence of postmortem redistribution”

“Forensic science in the dock” (and a related BBC commentary)

“Post-mortem clinical pharmacology”

Vidocq_CCAnd it is noon! My guest today is Peter W. Mullen! #cclivechatFri, 30 Mar 2012 15:59:57 +0000
pwmullen@Vidocq_CC just twitter web... #cclivechatFri, 30 Mar 2012 16:00:06 +0000
Vidocq_CCPeter Mullen is Consultant in pharmacokinetics and toxicology, instructor/trainer, and president of Kemic Bioresearch. #cclivechatFri, 30 Mar 2012 16:00:59 +0000
Vidocq_CC@pwmullen Tweetchat might be easier so you don't have to enter the hashtag #cclivechat the whole time. It does that for you. #cclivechatFri, 30 Mar 2012 16:01:36 +0000
pwmullen@Vidocq_CC Greetings all ! #cclivechatFri, 30 Mar 2012 16:02:01 +0000
Vidocq_CC@pwmullen tweetchat dot com, sign in, allow access, and enter the hashtag you wish to follow. #cclivechatFri, 30 Mar 2012 16:02:12 +0000
Vidocq_CCPeter wrote down a few introductory statements to set the scene for his session on “pharmacokinetics and postmortem toxicology” #cclivechatFri, 30 Mar 2012 16:02:58 +0000
Vidocq_CC@pwmullen Peter, Welcome and thank you for being with us this hour! #cclivechatFri, 30 Mar 2012 16:03:38 +0000
Vidocq_CC@bischofield Hi Brenda, thanks for joining! #cclivechatFri, 30 Mar 2012 16:04:03 +0000
Vidocq_CCPeter, can you explain in plain English what type of body fluids are best suited for postmortem toxicology tests? #cclivechatFri, 30 Mar 2012 16:05:00 +0000
katcop13RT @Vidocq_CC: #cclivechat at noon with @pwmullen on postmortem toxicology and pharmacokinetics http://t.co/r2U1REZSFri, 30 Mar 2012 16:07:52 +0000
Vidocq_CCAlso, are there body fluids least suited for postmortem toxicology tests? #cclivechatFri, 30 Mar 2012 16:08:08 +0000
Vidocq_CC@katcop13 Thanks, Kathleen and welcome back! #cclivechatFri, 30 Mar 2012 16:08:55 +0000
katcop13Come join #CClivechat & see what we can learn from @pwmullen on postmortem toxicology ~ #writetip #police #crimefiction #cclivechatFri, 30 Mar 2012 16:10:32 +0000
Vidocq_CCWow, something must be wrong again! I lost Peter and some on the web do not show up in tweetchat. #cclivechatFri, 30 Mar 2012 16:10:47 +0000
pwmullen@Vidocq_CC Various body fluids could be analyzed depending on availability in a particular case but blood is normally used #cclivechat 1/2Fri, 30 Mar 2012 16:11:16 +0000
pwmullen@Vidocq_CC but sampling site is important. #cclivechat 2/2Fri, 30 Mar 2012 16:12:21 +0000
bischofieldRT @katcop13: Come join #CClivechat & see what we can learn from @pwmullen on postmortem toxicology ~ #writetip #police #crimefiction #cclivechatFri, 30 Mar 2012 16:12:47 +0000
katcop13Glad to be back, @Vidocq_CC Thx for setting up live chats on Fridays 12-1 pm ET & for having @pwmullen as guest today
#cclivechat
Fri, 30 Mar 2012 16:14:01 +0000
bischofield@pwmullen @Vidocq_CC What is the best sampling site? #cclivechatFri, 30 Mar 2012 16:14:30 +0000
Vidocq_CC@pwmullen Are there any drugs that will not show up during testing? #cclivechatFri, 30 Mar 2012 16:14:47 +0000
pwmullen@Vidocq_CC Vitreous humor is also a good specimen since it represents a "protected site". VH is especially useful for alcohol #cclivechatFri, 30 Mar 2012 16:15:43 +0000
Vidocq_CC@pwmullen What is the max timeframe in which drugs in general show up in tests? #cclivechatFri, 30 Mar 2012 16:16:19 +0000
Vidocq_CC@LaughNYC @pwmullen Use hashtag #cclivechat or else, Peter does not see your tweets.Fri, 30 Mar 2012 16:17:16 +0000
pwmullen@Vidocq_CC Most drugs can be found pm but it's a matter of purposely looking for them. Also depends on dose, the time #cclivechat 1/2Fri, 30 Mar 2012 16:19:09 +0000
pwmullen@Vidocq_CC between its administration and death and between death and specimen collection. 2/2 #cclivechatFri, 30 Mar 2012 16:20:33 +0000
dtkev@pwmullen Generally it takes 4-6wks for tox.tests results I believe, do you see this improving in the future #cclivechatFri, 30 Mar 2012 16:21:28 +0000
Vidocq_CC@dtkev Good to see you and good question! #cclivechatFri, 30 Mar 2012 16:22:19 +0000
Vidocq_CC@pwmullen Can you give examples of general time frames for e.g. alcohol, coke, valium, etc? #cclivechatFri, 30 Mar 2012 16:25:16 +0000
pwmullen@Vidocq_CC Drugs (or especially metabolites) can be measured in URINE anywhere between a few hrs to weeks depending on the drug #cclivechatFri, 30 Mar 2012 16:26:28 +0000
katcop13@pwmullen What r some common misconceptions or errors (from public, media, TV, books) regarding postmortem toxicology? #cclivechatFri, 30 Mar 2012 16:28:40 +0000
pwmullen@dtkev 4-6 weeks is quite reasonable! It depends on the case (drug). I doubt this timeframe will change soon. #cclivechatFri, 30 Mar 2012 16:30:09 +0000
Vidocq_CCHow do you explain pharmacokinetics to folks who heard the word for the 1st time watching the Michael Jackson trial? #cclivechatFri, 30 Mar 2012 16:32:20 +0000
pwmullen@Vidocq_CC Remember it depends on the dose (& lab detection limit). Of course, also depends on the drug's pharmacokinetics. #cclivechat 1/2Fri, 30 Mar 2012 16:34:52 +0000
Vidocq_CC@pwmullen Can you give us more examples to get a feel for those time-frames? #cclivechatFri, 30 Mar 2012 16:36:57 +0000
Vidocq_CC@katcop13 Good question, Kathleen! #cclivechatFri, 30 Mar 2012 16:37:12 +0000
Vidocq_CCHello? I have the feeling either Twitter web or tweetchat is not working right. Can everyone see all the tweets? #cclivechatFri, 30 Mar 2012 16:38:59 +0000
pwmullen@Vidocq_CC Alcohol differs from most drugs in that its elimination from the body is "zero order" (rate not dependent on conc)2/2 #cclivechatFri, 30 Mar 2012 16:39:39 +0000
Vidocq_CC@pwmullen Peter, folks have asked questions. If you scroll down you'll see a few. More coming in! #cclivechatFri, 30 Mar 2012 16:41:30 +0000
pwmullen@Vidocq_CC Cocaine per se is eliminated quickly (Half-life approx 1 hr) but its key metabolites may be found in urine for days. #cclivechatFri, 30 Mar 2012 16:43:04 +0000
katcop13@Vidocq_CC I'm using TweetChat (there seems to be a pronounced delay in refreshing time), but otherwise ok, I think #cclivechatFri, 30 Mar 2012 16:43:34 +0000
Vidocq_CC@pwmullen The questions are from Adam, Brenda and Kathleen. #cclivechatFri, 30 Mar 2012 16:43:51 +0000
Vidocq_CC@katcop13 OK, delays here too. Thanks, Kathleen. #cclivechatFri, 30 Mar 2012 16:44:52 +0000
pwmullen@Vidocq_CC Valium (diazepam) has a fairly long half-life (ca 50 hrs) & its metabolites can be measured in urine for several days #cclivechatFri, 30 Mar 2012 16:46:40 +0000
Vidocq_CC@pwmullen Any famous cold cases that were considered lost but were "saved" thanks to the toxicology reports? #cclivechatFri, 30 Mar 2012 16:46:47 +0000
pwmullen@katcop13 These include: belief all substances are analyzed for; that insulin is the perfect "murder drug"; immediate results! #cclivechatFri, 30 Mar 2012 16:53:51 +0000
Vidocq_CCFive minute warning, folks! #cclivechatFri, 30 Mar 2012 16:55:56 +0000
katcop13@pwmullen Thanks! I was curious as to what people misunderstand ~ I can imagine it's a pet peeve 4 u & colleagues! #cclivechatFri, 30 Mar 2012 16:56:52 +0000
pwmullen@Vidocq_CC I've provided a brief explanation of pks in my intro on DCC. Important to emphasize pks has limited use in pm tox #cclivechatFri, 30 Mar 2012 16:58:10 +0000
Vidocq_CCIt is 1pm, folks! Thank you, Peter for being with us today and for answering the questions! Recap later on DCC. #cclivechatFri, 30 Mar 2012 17:00:40 +0000
katcop13Thx, @Vidocq_CC for hosting today, & thx @pwmullen for sharing your time & expertise with us! Have a grand weekend, all! #cclivechatFri, 30 Mar 2012 17:01:22 +0000
pwmullen@Vidocq_CC Certainly seems to be a delay in chat today! #cclivechatFri, 30 Mar 2012 17:01:52 +0000
Vidocq_CCNo #cclivechat over the Easter Weekend. #cclivechatFri, 30 Mar 2012 17:02:21 +0000
Vidocq_CCFriday after Easter the floor belongs to @trickycase and the Fingerprint Society Annual Conference! #cclivechatFri, 30 Mar 2012 17:02:43 +0000
Vidocq_CCOff to write the recap! Thanks, all! #cclivechatFri, 30 Mar 2012 17:04:55 +0000