the blood. It's a very, very small change. So even if you were to correctly subtract the baseline, the signal you would end up with is extremely tiny. In effect, probably in the upper 90 percent of the area of a given dose would have to be subtracted which would leave you with a very small signal, very highly variable, very difficult to do studies on. Probably any kind of reasonable size pharmacokinetic study done on the blood would probably fail even on a product against itself.
So the blood has proven to be not a very good site for sampling of this. It's good for most products and most types of drugs. However, in this particular one, urine has proven to be a much more effective means of assessing bioequivalence because, as I said, most, if not all, of the potassium you give in the dosage form to a normal healthy person comes out in the urine.
However, it's not quite that simple because that's not the only source of potassium that comes out in the urine. You actually, especially with normal subjects, have to eat, and if you have a several-day study and you try not to feed them, they get very angry and cranky. So you really have another source of potassium during your