AOD9604: What It Is and What It Does

What AOD9604 is

AOD9604 is a modified fragment of human growth hormone corresponding to residues 176-191 of the parent molecule, with an added cysteine so the peptide forms a stabilising disulfide bridge. It is supplied as an analytical-grade reference material for laboratory research.

Where it comes from

In the 1990s researchers at Monash University in Australia mapped the metabolic effects of growth hormone to its C-terminal region and made a synthetic fragment, hGH 177-191, capped with a tyrosine and later cyclised for stability. Metabolic Pharmaceuticals developed it as AOD9604 (Anti-Obesity Drug 9604), and a 2004 review in Current Opinion in Investigational Drugs records the programme as it moved through clinical trials.

What it does — in plain terms

Growth hormone does many things; the idea behind AOD9604 was to isolate just the piece thought to act on fat metabolism. In obese mice the fragment increased fat oxidation, and that finding launched a clinical programme in the early 2000s. In people the body-weight trials did not reach their goals and the programme was stopped. Later research moved to joints, with a rabbit osteoarthritis model, and to anti-doping laboratories, which needed to detect it.

How it works

The parent hormone raises fat breakdown (lipolysis) and lowers fat storage in adipose tissue. The 176-191 fragment was chosen because it carried that activity in cell and animal work without the growth-promoting and insulin-antagonising effects of the whole hormone; the 2001 mouse study reported higher fat oxidation with chronic dosing.

How the fragment does this is still argued. It does not bind the growth hormone receptor in the way the full hormone does, and it does not raise IGF-1, which is one reason the anti-doping literature treats it as distinct from growth hormone.

The joint work rests on a different idea: that the fragment can influence cartilage cells and inflammation locally when injected into a joint, which is what the rabbit osteoarthritis model tested with and without hyaluronic acid.

What the research shows

AOD9604 is a cautionary case worth reading closely. The animal data on fat oxidation are real, but the human body-weight trials that followed did not meet their endpoints and development stopped; a 2004 review captures the programme mid-stream. The more recent papers are a single animal joint study and analytical chemistry for sports-drug testing. Claims that outrun that record should be treated with suspicion.

• Current Opinion in Investigational Drugs, 2004 — reviewed AOD-9604's development as an investigational metabolic agent, summarising the preclinical rationale and the clinical programme then under way.
• International Journal of Obesity, 2001 — found that chronic treatment of obese mice with growth hormone or the modified C-terminal fragment increased fat oxidation and changed body weight.
• Annals of Clinical and Laboratory Science, 2015 — tested intra-articular AOD9604, alone and with hyaluronic acid, in a rabbit model of osteoarthritis and reported effects on cartilage scores.
• Drug Testing and Analysis, 2015 — characterised how AOD9604 is metabolised in vitro and how it can be detected, work driven by its appearance on prohibited-substance lists.
• Drug Testing and Analysis, 2013 — showed that AOD-9604 does not interfere with the WADA growth-hormone isoform immunoassay, confirming it is analytically distinct from the parent hormone.

What AOD9604 is studied for

Fat oxidation. The founding observation, in rodents: chronic dosing raised fat oxidation without the growth effects of whole growth hormone.

Body-weight change in trials. Human trials in the 2000s tested the fragment for body-weight change; they did not meet their goals and the programme was discontinued, a fact the published record should be read with.

Cartilage and osteoarthritis. A later line of work injected the peptide into joints in an animal model, with and without hyaluronic acid, to look at cartilage and inflammation.

Detection. Because the fragment is prohibited in sport, several papers establish how to detect it and confirm it does not confound growth-hormone testing.

Storage & handling

As a lyophilized (freeze-dried) powder, AOD9604 reference material is most stable kept cold and dark, refrigerated or frozen for longer holds. Once reconstituted with bacteriostatic water it should be refrigerated at roughly 2-8 °C, kept out of light, and protected from repeated freeze-thaw cycles.