So how do we infer, how do we measure whether that's actually happening? Through my process here, we go through drug passage through the gut wall. There are plenty of other steps that you could put into this. I've kind of over-simplified it. It passes into the blood. The blood acts as an intermediate transport area, carries it to the site of activity, and one gets therapeutic or pharmacodynamic effects.
Then as I mentioned yesterday, we've chosen, I think, as a matter of efficiency to do blood concentrations, when we can, for bioequivalence purposes simply because they are very close to the event we're trying to measure which is the only thing we really have control over which is the formulation. All the rest of these things are patient or subject physiology-related events. The thing that we really have control over is what does the formulation do, and formulation scientists can design it with various properties, release slower, release fast, or so forth, and so this is the both the thing that we're trying to measure and the thing that we actually have control over.
So we've chosen to measure in blood for