Posted by Larry Hoover on April 14, 2007, at 10:09:36
In reply to Re: Is phenylethylamine neurotoxic? » Larry Hoover, posted by falconman on April 13, 2007, at 9:54:03
> If feedback regulatory systems are everywhere, surely all drugs would 'poop out'? How come evan without 'drug/medication holidays' many don't? Just a thought.
One of the distinctive aspects of what I think of when I think of "drug" is the unnaturalness of the molecule, from an endogenous/exogenous perspective. A substance obtains the quality of being a drug by being outside the regulatory framework. That's not to say that regulatory processes cannot be activated in response to exposure, but that initial effects are due precisely to the foreigness.
Rather than supposing that drug poop out is an either/or situation, I perceive it as time-dependent. Given enough time, I'd expect every drug to poop out, eventually. The limit, of course, is infinite time, and nobody lives forever. But within lifespans of a population, some individuals will poop out after much shorter intervals of time than others. If observed for long enough, the incidence of poop out within the exposed population would rise towards 100%. Before it reaches 100%, some lucky folk simply haven't pooped out....yet.
Remember, I'm only suggesting a model. There are exceptions to everything that humans can imagine. The distinction between drugs and endogenous molecules is arbitrary; niacin is considered a drug at supra-physiological dosing.... Etc. Etc.
Lar
poster:Larry Hoover
thread:749466
URL: http://www.dr-bob.org/babble/20070413/msgs/749735.html