(please note followups; if you'd like to correct me, please add b.t. back
to the newsgroups line, but if you're more interested in the late Mr.
Foster, please respect the distribution.)
In article <629cag$t8g at bgtnsc02.worldnet.att.net>, gcruse at worldnet.att.net
> My question to this forum is a simple one. Is there a toxicologist in
> the house? If not, who can suggest the best news group to which to
> address the following question?
Will a pharmacology ABD do? One standard reference on drugs is Goodman and
Gilman's _The Pharmacological Basis of Therapeutics._ At the back of this
is a table of many drugs and their basic pharmacokinetics - how
well-distributed they are in the body, how long they persist in the body,
lots of other parameters.
> 197 pound man takes 50 milligram dose of trazadone less than 24 hours
> prior to his death. What are the chances that the standard test for
> anti-depressants in the blood would not detect that trazadone?
I can't help with this specifically, as I don't know what the sensitivity
of the standard test is for trazadone.
However, the half-life of trazadone is given in Goodman and Gilman as being
5.9 +/- 1.9 hours. This would mean that as much as 25% of the initial
concentration to as little as 3% of the initial concentration would be left
for an individual within one standard deviation of average. The volume of
distribution ("a measure of the apparent space in the body available to
contain the drug") for trazadone is 1 L/kg, so a 50mg dose in a 90 kg
person would wind up meaning that initial concentration would be about .5
mg/L. After 24 hours, you're looking at needing a test that can resolve 17
micrograms/L (3%) to be able to measure a dose within a standard deviation
of the mean half life.
> Are there important other relevant variables that we need to plug in such
> as how much he might have eaten, drunk, exercised, sweated, etc.?
Yes. The 17 ug/l requirement for sensitivity is a ballpark start; if I
were thinking about publicizing the result of a test for trazadone, I'd
probably want to know that I could detect it at a somewhat lower
concentration, probably I'd like to reliably detect it at 1.7 ug/l to be
tenfold more sensitive than the ballpark.
Anyone in b.t. know the specifics of the test procedures for trazadone, and
whether it's included in the panel of antidepressants routinely looked for?
> we know that the
> state examiner working with the autopsy doctor found no drugs in
> Foster's blood even though one of the tests he performed was for
Well, what he actually found was nothing at detectable levels. I would
hope that in his initial report he mentioned what the sensitivity of his
test was, and what drugs it screened for. Remember that there are a lot of
antidepressants out there; a test 'for antidepressants' isn't as good as a
test for trazadone per se, as the latter will likely be much more
> The FBI lab working for Robert Fiske, however,
> claims to have found traces of trazadone and some tranquilizers.
One interpretation is that the FBI lab has much better equipment and that
they knew what they were looking for by the time they were testing. The
black helicopter crowd will suggest, of course, that the FBI lab spiked the
> London Telegraph reporter Ambrose Evans-Pritchard called the Virginia
> toxicologist who performed the first test, Dr. Anh N. Huynh at
> <phone no. deleted>, and asked him how he might have missed the drugs. He
> responded that the amount was simply too small.
Well, if Evans-Pritchard is admitting that was Huynh's response, I expect
Huynh didn't see a problem with the difference in the results. Given E-P's
long interest in this case, I'm sure he was listening for, and hoping for,
any hint of emotion from Huynh about the discrepancy.
I'd guess the FBI lab ran a very sensitive test (probably high pressure
liquid chromatography) on the samples, while Huynh was using a test which
relies on a color change in the presence of some amount of tricyclic
antidepressants. The tricyclic antidepressants I've just looked up
(amitriptyline, desipramine, imipramine) share an interesting
characteristic in common: they all have half lives >15 hours. This means
that a test for 'antidepressants' might well be expected to do well with
them, as they're so much more persistent, where it would do much less well
on trazadone. Fluoxetine (prozac) has a half life of *fifty* hours, and
it's the most commonly prescribed antidepressant in use today.
I don't know how much trazadone is in use, but my guess would be that a
test looking for 'antidepressants' would be geared toward prozac and the
older tricyclics - all of which are quite persistent in the body and are
scrapie at super.zippo.com