Posted by Adam on April 11, 2002, at 14:50:01
In reply to Re: How to get a half-life... » Adam, posted by Elizabeth on April 11, 2002, at 9:02:26
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> Yes, that's my feeling. This isn't complicated stuff, although the inability to use proper notation on this board makes it look kind of messy and cluttered. Also, resorting to expressing stuff in terms of logs might be intimidating to some.
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Yeah, but I had a bit of an agenda here, a little paen to reductionism, if you will. One could easily just plug something into a calculator using these equations and have fun with it, and not worry about Vd's and AUC's and compartments and all that, or even the algebra.Suffice to say, the classic exponential rate law only works perfectly in a single compartment where distribution is instantaneous. I think, however, you could say it's also a good approximation for plasma levels from a single dose over time frames on the order of a half-life. Of course, elimination rates would tell you nothing about sertraline's effects on the CNS if it did not cross the blood-brain barrier, for instance. But, luckily, it does!
As for my being fond of reductionism, I guess it's my hope that someone might find as interesting as I do the fact that this simplified rate law is also the same for radioactive decay, or for guppies. I must confess I learned about many things and their rate of change in their own context without realising the connection was more than a kind of coincidence. When I understood the connection, I understood that many important processes in the world are ruled, fundamentally, by chance. So you can reduce many seemingly disparate phenomena down to the result of probability. The chance that a sertraline molecule will encounter a liver enzyme and be demethylated, the chance that an alpha particle will tunnel far enough out of a uranium nucleus that electrical forces overpower nuclear forces, and so on. All yield the same curve, basically.
> You know, if yesterday someone told me that today I would read a post here in which someone compared medications to fish, I wouldn't have believed it.
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Good! I think things like this are fun.Just as an aside, my fondness for guppies is personal: Whenever I had to go to the lab on a weekend, nixing some other plan, my S.O. would say "Oh, you have to feed the guppies." So now, any lab-related duty that interferes with my life is called "feeding the guppies." I wind up explaining all kinds of things in terms of guppies due to this association, and I find their pedagogical uses are quite impressive, as well as what I gain heuristically in trying to construct ever-more elaborate guppy analogies. Guppies have been more helpful to me than zebrafish ever could be!
poster:Adam
thread:101843
URL: http://www.dr-bob.org/babble/20020408/msgs/102774.html