A sports medicine expert says the drugs allegedly taken by James Hird are most commonly used in the "vanity industry" to improve appearance.
Sports physician Peter Larkins, speaking on behalf of Sports Medicine Australia, said Hexarelin was a well-known drug in the body image industry and was designed to give better muscle tone.
He said it was a peptide that was associated with increasing the user's production of natural growth hormone.
"The controversial one I suppose is Hexarelin because it is certainly not approved for normal medical use in everyday practice," Dr Larkins said.
"It is more a drug associated with research for its effect on muscle. It is used in that underground market - health clubs, gyms and body building."
Dr Larkins said Melanotan II was a research drug that was used to become more tanned without being exposed to the sun.
"It is associated with skin pigment, so it's used particularly in the body building world for people that are going into competitions," he said.