What it is
AOD-9604 is a lab-made piece of human growth hormone. Growth hormone is a large protein. Scientists thought one small part at its tail end did the fat-burning. They hoped this part would work without affecting growth or blood sugar.
AOD-9604 copies 15 amino acids (the building blocks of proteins) from that tail. It adds one more at the front, making 16 in total. That makes it a short chain of amino acids (a peptide).
It was made in Australia in the late 1990s and 2000s. The goal was a pill for obesity. In mice, it cut body fat. In people, the company’s largest trial found no real weight loss compared with a dummy treatment (placebo). Work on it for obesity stopped in 2007.
It is not an approved medicine anywhere. It is also not the same as the peptide sold as “HGH fragment 176-191”. That one has a different first amino acid.
AOD-9604 is Tyr-hGH(177–191): residues 177–191 of human growth hormone with an added N-terminal tyrosine (Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe), cyclised by a disulfide bond between Cys7 and Cys14 (C78H123N23O23S2, 1815.1 g/mol, CAS 221231-10-3).
The rationale was that lipolytic activity of hGH resides in its C-terminus, separable from receptor-mediated growth-promoting and diabetogenic effects. In obese rodents AOD-9604 reduced lipogenesis and increased lipolysis and fat oxidation, without the hyperglycaemia or insulin resistance seen with hGH. Heffernan et al. (2001) found that it increased β3-adrenergic receptor expression in adipose tissue, but that its chronic effects were absent in β3-AR knockout mice while acute fat oxidation persisted, so the mechanism was not resolved. No receptor has been identified, and the sponsor’s trials reported no change in IGF-1.
Pharmacokinetics are known only from animals: in pigs, intravenous AOD-9604 had a half-life of about 3 minutes, while oral dosing at 2 mg/kg produced a plasma peak at about 60 minutes (Moré and Kenley, 2014). Human pharmacokinetic data have not been published.
Who made it and when
The peptide came from Frank Ng’s lab at Monash University in Melbourne. His lab studied the fat-burning part of growth hormone. A Melbourne company, Metabolic Pharmaceuticals, developed and patented it in the late 1990s. It ran several human trials in the 2000s, mostly with tablets taken by mouth.
The main obesity trial failed in 2007. After that, the company (later part of Calzada Ltd) looked for other ways to sell it. In 2012 it said a panel of experts it hired had called AOD-9604 “generally recognised as safe” for use in food. This was the company’s own paid-for opinion. It was not an FDA decision. The company also patented uses for joint wear-and-tear (osteoarthritis) and cartilage repair.
Ng and colleagues at Monash reported the lipolytic and antilipogenic actions of synthetic hGH C-terminal fragments: AOD-9401 (Am J Physiol Endocrinol Metab 2000) and AOD-9604 (Horm Res 2000, in obese Zucker rats; Int J Obes and Endocrinology 2001, in mice). Metabolic Pharmaceuticals ran six randomised, double-blind, placebo-controlled studies (METAOD001–006), summarised by company-affiliated authors in Stier et al. (2013).
On 2012-06-25 Calzada announced a “conditional self-affirmed GRAS” determination by an expert panel it convened, for food use at up to 1 mg per person per day, conditional on publishing its safety data (published 2013–2014). A self-affirmed GRAS conclusion is the company’s own determination and is not reviewed or affirmed by FDA; FDA’s 2024 evaluation, which searched the GRAS Notice Inventory, did not cite any FDA GRAS notice for AOD-9604. Metabolic Pharmaceuticals holds US 10,111,933 and US 10,758,593, both titled “Use of growth hormone fragments”, with 2011 priority, covering osteoarthritis, cartilage and connective-tissue uses. Published cartilage data come from a rabbit osteoarthritis model (Kwon and Park, 2015).
What the data say
In fat mice and rats, AOD-9604 cut weight gain and body fat. It did not raise blood sugar. That was the original hope.
In people, the results did not hold up. Early small studies showed signs of more fat breakdown in the blood. But they found no clear weight loss.
A 12-week study of 300 people said weight loss was a little faster on the lowest dose. But only a short conference summary was ever published.
The largest trial had 536 people over 24 weeks, with diet and exercise. It found no real difference from placebo. The company then stopped.
The FDA found no human study of it as a shot under the skin or as a skin cream. Those are the forms proposed for pharmacy-made versions. In 2024 the FDA said there was not enough proof that it works for obesity.
Animal data: in obese Zucker rats, oral AOD-9604 500 µg/kg daily for 19 days reduced body weight gain by over 50% (Ng et al., Horm Res 2000). In ob/ob mice, 14 days by osmotic minipump or intraperitoneal injection reduced weight gain by about 5–10%, with increased fat oxidation and plasma glycerol and no change in glucose or insulin (Heffernan et al., 2001).
Human data (all oral or intravenous, as summarised in FDA’s 2024 review): METAOD002 (n=23, single IV doses 25–100 µg/kg) raised non-esterified fatty acids without significant weight loss. METAOD003 (n=16–17, oral 9–54 mg) and METAOD004 (n=36, oral 9–54 mg for 7 days) showed no significant weight loss. METAOD005 (n=300, oral 1–30 mg daily for 12 weeks) was reported only as an abstract: 0.22 kg per week at 1 mg versus 0.07 kg per week on placebo. OPTIONS/METAOD006 (536 enrolled, 502 randomised, oral 0.25–1 mg daily for 24 weeks) was powered to detect a 1.8 kg difference and did not reach significance at 12 or 24 weeks.
FDA concluded that in most of the studies it reviewed AOD-9604 did not reduce weight more than placebo, and found no human data for the subcutaneous or transdermal routes proposed for compounding.
Regulatory picture
There are three separate points here.
Approval: No medicine with AOD-9604 is approved by the FDA or any other regulator.
Pharmacy-made versions (compounding): In September 2023 the FDA put AOD-9604 on its “Category 2” list. This list is for ingredients with safety concerns for pharmacy mixing. The pharmacies that asked for it withdrew their requests. So in September 2024 the FDA took it off that list. But the FDA still reviewed it. In December 2024 an FDA expert panel voted 12 to 0. They voted against adding it to the list of ingredients pharmacies may use. It was also not among the six peptides in the US health department’s October 2026 draft policy easing enforcement.
Food use: The 2012 “safe for food” claim came from the company itself. It was not an FDA finding.
Sport: It is banned by the World Anti-Doping Agency. An Australian Crime Commission report named it among peptides given to athletes.
Approval: none. Development for obesity was terminated on 2007-02-21, and no IND-stage programme has been verified since. No study is registered on ClinicalTrials.gov.
Compounding: AOD-9604 entered 503A Category 2 on 2023-09-29 and was removed on 2024-09-27 after the nominations (Wells Pharmacy and the International Peptide Society) were withdrawn. FDA evaluated AOD-9604 (free base) and AOD-9604 acetate on its own initiative for obesity and proposed not adding them, citing poor physicochemical characterisation, missing endotoxin data for injectables, immunogenicity concerns, lack of efficacy and limited safety data. On 2024-12-04 the Pharmacy Compounding Advisory Committee voted 0 yes, 12 no, 0 abstain. It is not on the 503A bulks list in 21 CFR 216.23. No final FDA rule on AOD-9604 was found, and it is not among the six peptides covered by the HHS draft enforcement-discretion policy of 2026-10-30, so this article records compounding status as unknown.
Food: the 2012 GRAS determination was self-affirmed by a company-convened panel; no FDA review of it was found.
Sport and Australia: FDA’s review notes that WADA lists AOD-9604 under S2 (peptide hormones, growth factors and related substances), that the Australian Crime Commission reported its supply to athletes, and that Australia’s Advisory Committee on Medicines Scheduling recommended adding it to the Poisons Standard as a performance- and image-enhancing drug.
