Chris Zell wrote:
> I don't understand how the whole of medicine can rest on the assumption > that simple diffusion can get extremely small doses of medicine to the > proper receptors. Like DNA "telekinesis"? I guess you've never been involved with setting doses through titration, then. It's not generally a fun thing to do but it does clarify the process enormously. The blood gets stirred very thoroughly in the course of going around the loop. "Titrating" the dose is adding enough medicine to the body to get the blood concentration to the desired value, with frequent blood samples drawn in order to measure said concentration. The blood concentration is directly tied to the concentration at the site where the medicine is needed, and in general medicines act in a way that's broadly similar to what they do to individual cells in vitro when the in vitro concentration is in the same ballbark as the blood level used in treatment. You may be aware that doses in medical literature are typically quoted not as "total mg needed for the effect" but are, rather, quoted as "mg per kg needed for the effect". If you weigh 100 kg you need twice the dose of someone who weighs 50 kg. The daily dose of phenobarb needed for a 2 pound rabbit with epilepsy is not the same as the dose needed for a 60 kg human with epilepsy (and titrating the dose in such a case is very rough on everyone involved). In short, your *whole* *body* gets dosed up to the necessary level, not just the "proper receptors". God is not doing the driving to see that the medicine goes to the right place -- in fact, *nobody* is doing the driving, and the medicine goes all over the place, hitting every cell in your body which is directly tied to your circulatory system (brain cells and corneal cells are two notable cases of cells which are not tied directly to the blood circulatory system). Most medicines have a wide enough useful range of activity that one can just go by general dose guidelines without precise dose titration (or one can boost the dose until the desired result is observed, which is, of course, a very crude form of titration). Medicines with nasty side effects at slight overdose are the common exception to this. Most things that do stuff to cells are poisons rather than medicines because they don't exhibit their activity at a concentration which is low enough that we can tolerate that concentration throughout our whole body. In cases where the blood stream doesn't go where we need the medicine, such as tumors with poor circulation within, or with things which must affect the brain, or with infections which have become 'walled off', well, the medicine typically doesn't work. One either finds a medicine which somehow gets past the barrier, or one doesn't, and in the latter case one lives with the disease, waits for the immune system to take care of it, or one dies. There is no magic in how medicine gets to the "proper receptors". And life doesn't make entropy decrease, and the body doesn't suddenly lose an ounce or two at the moment of death, and ... ça suffit.
