THE Essendon footy club probe has dramatically expanded, with the world anti-doping watchdog now considering whether four additional drugs allegedly given to players should be retrospectively banned.

The World Anti-Doping Agency has confirmed it was assessing the status of the drugs.

The move casts further doubt on whether the Bombers probe can be thoroughly completed by the August deadline.

The four drugs - TA65, Melatonan II, Interleukin 6 and Cerebrolysin - are suspected of having been administered to Bombers players.

WADA said in a statement: "In relation to (these) substances, we can confirm that information in respect of these substances is being gathered, and appropriate consideration will be given as to their status under Section S0 of the list or elsewhere in due course."

AFL backtracks on timeline

The Australian Sports Anti-Doping Authority yesterday said it was consulting with WADA on the outcome.

The Herald Sun has established that clinical records and correspondence handed to ASADA for investigation include evidence that:

A BOMBERS star was given the anti-ageing drug TA65 early in last year's competition season.

A SMALL number of players had been injected with Interleukin 6 at least once.

PLAYERS were injected with an unspecified type of Melatonan.

PLAYERS were given Cerebrolysin as part of a schedule of injections complemented by hyperbaric treatment.

The Herald Sun has confirmed that Bombers coach James Hird had attended hyperbaric clinic Hypermed with former sports scientist Stephen Dank and other staff in 2012.

TA65, Melatonan II and Cerebrolysin, along with anti-obesity drug AOD-9604, were identified in the Australian Crime Commission's February report as having been given to players but were said not to be prohibited by WADA.

But WADA has told the Herald Sun the status of all these substances is now under review and they may yet be declared prohibited.

"Every year there are many new or modified substances released onto the market or black market.

"There are also people willing to use experimental substances and methods not yet clinically tested or approved for human use. It can take considerable time and analysis before we are aware of the status of these substances,

"In relation to (these) substances, WADA can confirm that information in respect of these substances is being gathered, and appropriate consideration will be given as to their status under Section S0 of the list or elsewhere in due course."

ASADA yesterday said it was consulting with WADA on the outcome of that analysis. It could not say if it would be completed before August when the authority is due to deliver its report on the Bombers' supplements.

In April, WADA declared that AOD-9604 had been prohibited since January 2011 under the S0 category, which bans any drug that has not been approved for human use by government health regulators.

Essendon is trying to defend that drug by obtaining "independent advice" from unnamed experts that it does not enhance performance. Consent forms before ASADA indicate that players were told they were to receive it.

The Herald Sun reported in May that the anti-ageing drug TA65 had formed part of the ASADA probe.

Anti-ageing medic Dr Robin Willcourt, who is pushing to have TA65 approved for use here, said he had been told an Essendon player had tried it but that he was unaware of its widespread use among athletes.

"I do not know what happened, I heard he had it but I don't think he continued on it," Dr Willcourt said, adding that in his opinion it should not be WADA-banned.

Dr Willcourt has previously told the Herald Sun he had given a small amount of TA65 to Dank.

A source familiar with Essendon's attendance at Hypermed confirmed Hird had been present with Dank, sacked high-performance coach Dean Robinson, players and other staff last year.

However, Hird is believed not to have played a role in overseeing the treatment regime.

Hypermed owner Dr Mal Hooper would not comment on the Essendon matter but said hyperbaric treatment was common for athletes.

"It is commonplace for athletes, and most international clubs including soccer, NRL and basketball use hyperbaric," he said.

Dr Hooper is considering challenging a charge of professional misconduct levelled at him in a tribunal last month.

The charge does not relate to his work with Essendon and he has co-operated with ASADA investigators, answering questions and turning over documents.

The Herald Sun revealed in May that ASADA is building a strong circumstantial case that Essendon players may have been given banned drug Thymosin beta 4, which commonly used in racehorses.

AFL deputy chief executive Gillon McLachlan said the AFL had not pressured ASADA to hurry probe, despite earlier this week declaring the AFL was resolved to having it completed next month.

On Wednesday, Mr McLachlan said the league was "committed to bringing this investigation to an end with ASADA in August, prior to the finals series" but yesterday said the AFL was a junior partner in the investigation and that ASADA would decide the timeline.

"ASADA will finish this investigation when they get it done ... I don't think we would have the ability to influence them to get things completed ahead of time."