A drug that is being trialled by several AFL clubs to help aid player recovery, has not been approved by the AFLโ€™s head doctor Peter Harcourt.

Information surfaced on Wednesday of up to seven clubs trialling pentosane polysulfate sodium injections to cure osteoarthritis, knee, hip and groin pain and aid recovery for players.

The trial is in phase two of the Therapeutic Goods Administrationโ€™s โ€œspecial access schemeโ€.

AFL legend, Malcolm Blight expressed his concerns on SEN on Thursday morning over AFL players being used as โ€œlab ratsโ€ in a medical trial that has not been cleared by the department.

โ€œIโ€™ve never heard, in 50 years, where the AFL have been involved or anyone in the AFL has been involved in trials with drugs,โ€ Blight told SEN.

โ€œThey are well and truly run, won and done prior to any other time, any other country.

โ€œTheyโ€™re certainly not to use as lab rats on AFL players ... thatโ€™s the way it reads, and if thatโ€™s the case I should think thereโ€™s going to be a fair bit of noise about this.

โ€œI just couldnโ€™t imagine weโ€™d be trailing stuff on guys youโ€™re paying $1.2, $1.3 million.

โ€œAnd I know you (could say) โ€˜where do you trial it?โ€™ Well, you trial it elsewhere.โ€

The AFL have confirmed that it is not a banned substance however they insist they have not approved for it to be used on players.

โ€œDr Peter Harcourt did not approve this medication,โ€ an AFL spokesman said.

โ€œThe medical director of the AFL was asked whether the substance was prohibited under the WADA Prohibited List and he stated that it is not listed on that list.

โ€œIt is a misrepresentation of the role and the views of the AFL medical director to say that he approved this medication.โ€

Chief executive of Paradigm Biopharmaceuticals, Paul Rennie, said Dr Harcourt sent out an email in 2015 saying that so long as the drug was not on the WADA banned substances list, it was up to club doctors to decide whether they used it on their players.

โ€œBefore we went anywhere near the first player the club doctor involved ran it past Dr Peter Harcourt as a final check and there were no objections,โ€ Rennie said.

โ€œI called him (last night) to reconfirm that the issue of using pentosan polysulfate sodium was discussed in 2015.

โ€œHe further confirmed that use of the drug on AFL players was a decision of the club doctor.โ€

Pentosan polysulfate sodium has previously been used to treat blood clots and a painful bladder syndrome in women but not for osteoarthritis.

The drug has been injected into injured players twice a week for six weeks, including an interstate star battling an extensive knee injury.