Illustration: Matt Golding. Scientific documents obtained by Fairfax show the Melbourne company that holds worldwide patents for AOD-9604, Metabolic Pharmaceuticals, delivered the drug intravenously to participants in only one of the four Australian human clinical trials held to determine its safety and effect as an anti-obesity medication. In the intravenous trial, participants were infused with AOD-9604 just three times, and the average dose ranged from 9.7 milligrams to 58.2 milligrams. The trials found the drug to be safe when administered at that volume and frequency, but ineffective as a fat-buster. Data shows participants in the intravenous trial reported 118 adverse events, with three deemed severe. One participant experienced chest constriction, while 69 per cent of participants reported mild to moderate headaches. While Watson's admission last week that he was injected with AOD-9604 - which is banned by the World Anti-Doping Agency because it is not approved for human use - has fuelled debate about possible player sanctions and Brownlow Medal revocation, the issue causing greater concern among AFL powerbrokers, the players' association and anti-doping investigators is that of player welfare.

''WADA were shocked by some of the substances going around Essendon and some of the NRL clubs. Some of those drugs had not been thought of in a sporting context before,'' said a source familiar with the progress of the Australian Sports Anti-Doping Authority's inquiry. ''We've got a playing generation of guinea pigs.'' Documents show that some AOD-9604 intravenous trial participants reported a euphoric effect. An international patent was filed in 2003 to develop the drug as an antidepressant. The reported euphoric effect raises questions about whether the repeated injecting of AOD-9604 in Essendon players posed any addictive problems. Essendon's former sports science chief Stephen Dank has stressed he never gave anything harmful or illegal to the players. But no one from Essendon has explained why fit young men would need a failed anti-obesity drug or extracts of pigs brains - the drug Cerebrolysin - used to treat senior citizens with dementia. Contacted by Fairfax on Friday, Mr Dank denied measuring the effects of various drugs in Essendon players and said he was unaware of any information being passed to external parties.

In a statement, Essendon Football Club said it had no knowledge of any ''clinical trial'' and ''if this is found to be true, it is deeply distressing and disturbing, and goes to the heart of what may have been perpetrated at our club. ''We are in the hands of ASADA, and we continue to support our players during this process and we have brought in independent medical and pharmacological advice, which has provided comfort to the club about the safety of our players. ''We have been limited in what we can comment on, and more than anything else, we want the ASADA investigation to be completed. There is information we still do not have as a club and we are looking to the ASADA investigation to uncover the full extent of what happened at the club.'' In April, Metabolic chief executive David Kenley spoke of his surprise when Mr Dank told him last year that he was using AOD-9604 at Essendon to aid player recovery. ''I wasn't sure it was the right environment. At that stage, we had no firm animal data to indicate that it could work in a human in ways that he wanted,'' Mr Kenley said. He has not returned calls in the past week.

Fairfax Media has not seen any evidence to suggest a financial link between Mr Dank and Metabolic, and Metabolic says it was not providing any incentives to him. Nor has any evidence been produced to suggest information on the performance of Essendon players given certain supplements was passed to external parties. Documents lodged with the Australian Securities Exchange last year by Metabolic's listed parent company, Calzada Ltd, show the company had lodged patent applications covering AOD-9604's use in cartilage and muscle repair medicines at the same time the drug was being used at Essendon. The patent applications came after Metabolic received results of Canadian testing in animal cells that showed AOD-9604 ''has a positive (anabolic) effect on cartilage tissue formation'', according to a company statement to the ASX. Internal Metabolic 2011 emails obtained by Fairfax Media show the company was trying to gather all data related to AOD-9604's effect on muscle cells, with its executives excited by the drug's popularity in the body-building scene and the big sums earned by Chinese black market manufacturers. Mr Dank last year helped arrange for Essendon chairman David Evans, who runs an investment broking firm, and coach James Hird, a trained stockbroker, to receive a stockbroker briefing on the company's prospects.

A text allegedly sent by Mr Dank to Hird last year, which was reported by ABC television's 7.30 program earlier this year, stated: ''financials ready for you and David for AOD project. These financials cover all possible revenue streams, where the project applies.'' It is not known if the David referred to in the text refers to Mr Evans or Mr Kenley. Neither Mr Evans' company nor Hird invested in Metabolic. Another Melbourne company, Phosphagenics Ltd, has confirmed that it recently stopped using AOD-9604 in an anti-cellulite cream sold over the counter at Myer and David Jones. Loading Phosphagenics, which is led by a former Metabolic executive, had been using the drug in the cream since 2011 under licence by Metabolic. Phosphagenics sourced its AOD-9604 from Taiwan because Metabolic no longer produces it.

A Phosphagenics executive said the decision to stop using AOD-9604 had nothing to do with its effectiveness. The company had found cheaper alternatives that worked equally as well, he said.