Basically, if you use it medically, a patch releases it slowly into your blood over the course of about 24 hours, and it reaches something like an equilibrium and stays there.
But, if you take it recreationally, you get a big pulse. The first organs to see it will take in a lot of it. As is spreads through the body, the blood concentration reduces, and the organs that took up that big pulse give some back. This is a pretty passive process, so it continues even after you die.
What the ME should have done (and maybe did do) is draw blood from several different points in his body, along with tissue samples from several organs, then send them all off for testing. All of that data together could be used to basically reconstruct the fatal dose.
How does fentanyl concentration go up after death? Doesn't it break down into metabolites like norfentanyl (which shows up in his tox report)
It diffuses out of organs.
Basically, if you use it medically, a patch releases it slowly into your blood over the course of about 24 hours, and it reaches something like an equilibrium and stays there.
But, if you take it recreationally, you get a big pulse. The first organs to see it will take in a lot of it. As is spreads through the body, the blood concentration reduces, and the organs that took up that big pulse give some back. This is a pretty passive process, so it continues even after you die.
What the ME should have done (and maybe did do) is draw blood from several different points in his body, along with tissue samples from several organs, then send them all off for testing. All of that data together could be used to basically reconstruct the fatal dose.