UPJOHN'S DRUG XANAX ON TRIAL
Steven B. Harris
sbharris at ix.netcom.com
Tue Mar 24 17:46:57 EST 1998
In <01bd5717$830d6780$215971cf at none.fsxnet.com> "Harmon"
<dontspamme at spam.not> writes:
>Actually, there are ways to predict how people will react to drug
>ED50 - effective dose in 50% of test population
>LD50 - lethal dose in 50% of test population
>TD50 - toxic dose in 50% of test population
>TI - therapeutic index - measures drug safety, measured by LD50/ED50
None of these are perfect predictions, although they provide better
probabilistic information than a guess. This should be obvious,
inasmuch as LD50 values don't even agree perfectly between species.
Sometimes they vary wildly. For example: my Merck Index tells me that
oral LD50 for digitoxin (not to be confused with digoxin) in guinea
pigs is 60 mg/kg. In cats, it's only 0.18 mg/kg. That's a pretty wide
margin! In humans, I believe that it's somewhere in between.
Steve Harris, M.D.
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