- Jul 27, 2010
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Well, it seems I was wrong that the blood test of CB rules out transfusion. Apologies to those who were reading along.
It turns out that when most drugs are administered IV, they immediately distribute into a far larger volume than blood, which lowers the theoretically expected blood concentration. I didn't realize this, because radioactive tracers are routinely used to measure blood volume. This is based on the premise that they distribute only into blood. But apparently the same principle does not work for most drugs. I have checked some studies, and following IV administration, the peak blood value is consistently 30-50 times lower than one would expect if all of the drug were distributed only into the blood stream. It would probably be the same for CB.
The theoretical blood level following IV administration of CB would still be somewhat higher than that following oral, maybe 2-3 times higher. So a very low value like 1 pg/ml probably favors oral ingestion significantly. But I wouldn't say it's a slam dunk, it is just one piece of evidence on the scale.
Just to be clear, I have always thought Bert probably transfused, because of the DEHP value. The question is whether transfusion could be the source of the CB. There are still problems with this. Bert’s team raised the objection that it would take a very high dose of CB to get enough in a small volume of blood used for transfusion. One of WADA's counter points was (apparently) that a very low dose of CB, just a few hundred ng, would be effective if taken IV. But if an IV dose is distributed into a far larger volume than just the blood, the difference in effectiveness between oral and IV would not be that great. Any drug taken IV will of course act faster, it has a head start to its target, but the total effect would not be that much greater. So the objection from Bert's side that the dose would have to be quite high, though not the deal-breaker they claimed it to be, does carry some weight.
So I think transfusion alone and transfusion plus contaminated supplement are still both viable hypotheses. As I noted in my previous post (edited), Bert might have taken a contaminated supplement shortly before his July 20 test and still tested negative. This would eliminate the need for separate transfusions on two days, as well as the need to take a high dose of CB to get enough in the withdrawn blood.
My larger point, though, is still valid. If CAS wants to rule that it was contaminated supplement, they should confront the fact that it almost certainly was clean by antidoping standards.
It turns out that when most drugs are administered IV, they immediately distribute into a far larger volume than blood, which lowers the theoretically expected blood concentration. I didn't realize this, because radioactive tracers are routinely used to measure blood volume. This is based on the premise that they distribute only into blood. But apparently the same principle does not work for most drugs. I have checked some studies, and following IV administration, the peak blood value is consistently 30-50 times lower than one would expect if all of the drug were distributed only into the blood stream. It would probably be the same for CB.
The theoretical blood level following IV administration of CB would still be somewhat higher than that following oral, maybe 2-3 times higher. So a very low value like 1 pg/ml probably favors oral ingestion significantly. But I wouldn't say it's a slam dunk, it is just one piece of evidence on the scale.
Just to be clear, I have always thought Bert probably transfused, because of the DEHP value. The question is whether transfusion could be the source of the CB. There are still problems with this. Bert’s team raised the objection that it would take a very high dose of CB to get enough in a small volume of blood used for transfusion. One of WADA's counter points was (apparently) that a very low dose of CB, just a few hundred ng, would be effective if taken IV. But if an IV dose is distributed into a far larger volume than just the blood, the difference in effectiveness between oral and IV would not be that great. Any drug taken IV will of course act faster, it has a head start to its target, but the total effect would not be that much greater. So the objection from Bert's side that the dose would have to be quite high, though not the deal-breaker they claimed it to be, does carry some weight.
So I think transfusion alone and transfusion plus contaminated supplement are still both viable hypotheses. As I noted in my previous post (edited), Bert might have taken a contaminated supplement shortly before his July 20 test and still tested negative. This would eliminate the need for separate transfusions on two days, as well as the need to take a high dose of CB to get enough in the withdrawn blood.
My larger point, though, is still valid. If CAS wants to rule that it was contaminated supplement, they should confront the fact that it almost certainly was clean by antidoping standards.
