Chris Froome's salbutamol defence boosted by scientific study

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Chris Froome's tilt at the Giro d’Italia didn't get off to the best start when he crashed during a recon of the opening time trial, but the battle to prove his innocence in his salbutamol case may have received a boost following the publication of a new scientific study.

A research paper published last week in the British Journal of Clinical Pharmacology, and highlighted in an article on The Times website on Monday, has called the efficacy of the testing procedures for salbutamol into question.

The paper, titled the 'Futility of current urine salbutamol doping control', concluded that it was not feasible to determine a dosage level based on the results of a single ‘untimed’ urine sample.

Froome returned a salbutamol level of 2,000ng/ml in an anti-doping urine test conducted during the final week of last year’s Vuelta a España. The reading was twice the permitted level set out by the World Anti-Doping Agency (WADA). Froome and his legal team are attempting to prove that, despite the reading, he did not exceed the permitted dosage. If he is found to be guilty, he could face a lengthy suspension and may have results struck from his palmarès – though which ones remains unclear. Froome has always maintained his innocence and has defended his decision to continue racing sub-judice.

The new study used simulations to predict the concentration of salbutamol in urine, using a model of inhaled and orally administered salbutamol, with an input of 800mcg – WADA’s maximum allowed dosage. Most of the parameters used came from literature on adult humans but the study also used parameters on absorption and distribution from literature on dogs.

According to the report, as many as 15.4 per cent of the simulations resulted in the levels of salbutamol in the urine exceeding the 1,000ng/ml limit set out by WADA. It states that "the current threshold inadvertently leads to incorrect assumptions of violation, whereas many violations will go unnoticed" and says that the testing should be reconsidered.

The study was performed by researchers at the Centre for Human Drug Research in Leiden, the Netherlands, and led by Jules Heuberger, who last year published a study on the effects of EPO, concluding that it did not improve performance.

Unlike other substances on WADA's banned list, salbutamol is 'specified', meaning Froome does not automatically receive a provisional suspension, and can continue racing. However, the onus is on him to prove how such levels got into his urine sample. Froome's legal team, led by lawyer Mike Morgan, has looked at a number of different defences. In January it was reported that they were looking into using kidney malfunction as a defence, claiming that Froome’s kidneys retained salbutamol from previous days before releasing it all at once.

The effects of dehydration have also been examined and, under new WADA regulations that take this and urine concentration into account, Froome’s levels have been revised to 1,429ng/ml, according to The Times. Though much lower than the original 2,000ng/ml, this revised level would still constitute an adverse analytical finding (AAF).

The findings of this study could prove a major boost for Froome and his legal team, and The Times reports that they are likely to use it as part of their defence. However, WADA remains confident of their own scientific findings on the subject and do not believe that the threshold of 1,000ng/ml requires changing.

"I read the article you refer to, and no, no concern at all. Nothing new, as their model is based on three well-known studies," WADA science director Dr Oliver Rabin told The Times.

"WADA has conducted several studies on salbutamol and continues to conduct studies on beta-2 agonists. We believe the current threshold is solid considering the scientific literature published on salbutamol over the past 20 years. Based upon the published and unpublished information in our possession, we see no reason to change the salbutamol threshold."

Almost eight months after he was notified of the test results, Froome’s case does not appear to be anywhere near its conclusion. There is no prescribed timeline for the case and it could drag on through the Tour de France in July and beyond.