thehog said:
Re: blood transfusions, it’s more possible that he was taking salbutamol orallly prior to withdrawal, which has many more performance enhancing effects than via inhaler and much stronger doses. When he re-infused he kicked over the threshold.
Yes, but he'd still have to take a boatload to get a urine concentration that high from a blood transfusion. And why would he be taking any at all, except possibly to counteract genuine ashthma, during the offseason, when he most likely would be withdrawing?
With regard to the PE effects of oral doses, here's a study that reported a significant increase in peak power in an anaerobic bike ergometer test:
https://www.ncbi.nlm.nih.gov/pubmed/25077918
As the authors note, this would help sprinters, not GT men, but hey, Froome has won some crucial time on some sprints recently.
I would also add, he may have tripped the tripwire in the past and the UCI have in confidence accepted his explanation. He certainly appeared very casual about this situation since September until it leaked.
Yes, can't rule this out. But I don't think even a protected rider could get away with this very often.
Here's some more relevant literature:
https://www.ncbi.nlm.nih.gov/pubmed/22388343
https://www.ncbi.nlm.nih.gov/pubmed/19927035
These two studies by the same group measured urinary levels of salbutamol four hours after inhaling 800 ug (which is the 12 hour limit set by WADA). In the first study, only 1/18 subjects exceeded the 1000 ng/ml. urinary limit, and not by much (1057). Eight of the subjects were described as elite athletes with ashthma, and had a mean urinary level of about 335 ng/ml. Moreover, if the urine concentration in that one high sample was corrected for specific gravity—i.e., dehydration makes the urine solutes more concentrated than normal—the salbutamol concentration dropped to 661. I don’t know whether in the WADA testing procedure, this correction is carried out or not, but regardless, I assume the 1000 ng/ml was found to be appropriate to however the urine is treated. I also need to point out I saw another study reporting that making the SG correction actually increased the effective concentration, so sometimes subjects being tested apparently have very dilute urine.
In the second study, the mean value of ten subjects was just 261 ng/ml. So clearly, at the maximum permitted doses, going over the urinary limit is not common. In contrast, in both these studies, subjects also took 8 mg (ten times the inhalation dose) orally. The mean urinary values were 2000-3000, though there was enormous individual variation, as indeed, is the case regardless of route of administration.
https://www.ncbi.nlm.nih.gov/pubmed/16541373
In this study, the authors administered 100 ug doses of salbutamol twice daily to ten subjects, and on the basis of the urinary levels, concluded that the WADA limit could be lowered to just 250 ng/ml. Someone here who takes salbumatol can comment on whether 200 ug/day is a reasonable dose, or whether the 800 – 1600 ug dose is really necessary.
Another study reported a false positive rate of 4% using 500 ng/ml as the limit, but the amount inhaled was not given in the abstract. Also, the amounts will vary depending on whether the free or conjugated forms of the drug are measured. I'm not clear yet on whether the WADA urinary limit refers to free salbutamol or total, which makes a substantial difference, and also whether, as I mentioned above, the urine is corrected to a typical value of specific gravity. But overall, I think we can conclude that a value of 2000 ng/ml, as reported for Froome, is far more likely to result from an oral dose than an inhaled one. From what I've seen so far, I'd be a little surprised if he could get a urinary level that high by inhaling within the WADA limit.
Another interesting aspect of this is that in theory, one can distinguish inhaled from oral salbutamol from the ratio of free to sulfated, but this is difficult, apparently because when one inhales, one may actually swallow some of the substance? Maybe an asthmatic can comment on this?