AOD 9604

Origin and structure

AOD-9604 is a synthetic chain of 16 amino acids: Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe, with a disulphide bridge between its two cysteines. It copies amino acids 177 to 191 at the tail end of human growth hormone, a protein of 191 amino acids, and adds a tyrosine at the front to stabilise the peptide. Its formula is C78H123N23O23S2 and its molar mass about 1,815 g/mol.

It grew out of work by Frank Ng's group at Monash University in Melbourne, which reported that the tail end of growth hormone carries much of the hormone's fat-mobilising activity. The Australian company Metabolic Pharmaceuticals developed and patented AOD-9604 in the late 1990s and between 2001 and 2006 ran six clinical trials in Australia, testing it against obesity, first as an intravenous infusion and then as a pill. After the largest trial failed in 2007, the company repositioned it as an ingredient for foods and supplements. It is also sold as a research chemical, and US wellness clinics offer it as injections or oral products.

How it is thought to work

In obese rodents AOD-9604 slowed weight gain and increased fat breakdown. Obese Zucker rats given it by mouth every day for 19 days gained less than half the weight of untreated rats (15.8 g against 35.6 g), and their fat tissue broke down fat faster. In obese mice treated for 14 days it raised fat burning and blood glycerol, a marker of fat breakdown, without the rise in blood sugar and fall in insulin release seen with full growth hormone.

Unlike growth hormone, it did not compete for the growth-hormone receptor or make receptor-bearing cells divide in the test tube, and in the human trials it did not raise IGF-1. One mouse study suggested that its effect on fat depends partly on β3-adrenergic signalling, but the FDA's 2024 review concluded that its molecular target and mechanism remain unknown.

It is broken down within minutes: its half-life was about 4 minutes in rat plasma in the test tube and about 3 minutes after an intravenous dose in pigs. No human pharmacokinetic data have been published, so it is not known how much reached the blood in the oral trials, and no one has measured blood levels after an injection under the skin.

Is AOD-9604 approved?

No. No medicines regulator has authorised it: the FDA's 2024 review found no listing with the EMA or national medicine registers, no monograph in the European, US, Chinese, Indian or Japanese pharmacopoeias, and no approved drug that contains it. In the Netherlands it is not a registered medicine, so it may not be sold or promoted for use in people; it is available only as research material, which is the basis on which our shop sells it.

In the United States, pharmacies have no legal basis to compound it: it has no USP monograph, is not part of an approved drug and is not on the 503A list. The FDA had placed it in Category 2 of its compounding policy, for substances that may present significant safety risks, citing possible immune reactions, peptide impurities and serious adverse events with unclear causality. After the nominations were withdrawn, the FDA evaluated it for obesity on its own initiative and proposed not adding it to the 503A list of substances pharmacies may compound: it judged the substance not well characterised, found no evidence that it works and called the safety data insufficient. On 4 December 2024 its Pharmacy Compounding Advisory Committee agreed, voting 12 to 0. No proposed or final rule had followed by October 2026, and the FDA still lists AOD-9604 among withdrawn nominations, with the same safety warning.

The GRAS status often quoted online is something else. In June 2012 a panel of experts hired by the company concluded that AOD-9604 is generally recognised as safe as a food ingredient, at a total intake of up to 1 mg a day, on condition that its safety studies were published; they appeared in 2013 and 2014. The company itself called this a self-affirmed determination. It was never submitted to the FDA, AOD-9604 does not appear in the FDA's GRAS Notice Inventory, and it is not a drug approval: it says nothing about injections and has no legal effect in the EU.

In Australia, where it was developed, it was added to the national Poisons Standard alongside other performance- and image-enhancing drugs, which makes possession without a prescription or other authority illegal. In sport it is prohibited at all times: the WADA Prohibited List names AOD-9604 as an example of a growth-hormone fragment in class S2.2.3, and the Dutch anti-doping rules apply the same list.

What the research shows

The animal work is small: a handful of rodent studies, mostly from the Monash group behind the peptide, and one rabbit study. The human record is six randomised, placebo-controlled trials that Metabolic Pharmaceuticals funded and ran in Australia between 2001 and 2006, with 893 participants in all. None of the efficacy trials was published in full in a peer-reviewed journal. What is known comes from conference abstracts, company announcements to the stock exchange and a pooled safety paper by authors who worked for or advised the company.

• Four pilot trials: 15 to 36 men each, given single intravenous doses or oral doses for up to seven days. In two of the trials in men with obesity, free fatty acids in the blood, a marker of fat breakdown, rose within hours of dosing; in none did weight fall significantly more than on placebo.
• 12-week phase IIb trial (2004): 300 adults with a BMI of 35 or more took one of five oral doses or placebo daily. All doses lost slightly more weight than placebo, with no clear dose-response; the lowest dose did best, losing 0.22 kg a week against 0.07 kg on placebo. In the company's primary analysis that difference was not statistically significant (p = 0.1), and the efficacy results appeared only as a conference abstract.
• OPTIONS trial (registered 2005, reported 2007): 536 adults with obesity enrolled and 502 were randomised to one of three lower oral doses or placebo daily for 24 weeks, alongside a supervised diet and exercise programme. The trial was powered to detect a 1.8 kg difference from placebo at 12 weeks. Weight loss compared with placebo was too small to be statistically significant at 12 or at 24 weeks, and on 21 February 2007 the company ended development for obesity.
• Safety across the six trials (Stier et al., 2013): IGF-1 and glucose tolerance did not change, no antibodies against AOD-9604 were found, and adverse events were about as common as on placebo.
• Osteoarthritis: a single study in 32 rabbits with chemically induced knee damage found less cartilage damage after weekly injections into the joint, more so combined with hyaluronic acid (Kwon and Park, 2015). It has never been tested for joints in people, and no AOD-9604 trial has been registered on ClinicalTrials.gov.

AOD-9604, HGH fragment 176-191 and growth hormone

The names are often mixed up. The natural fragment hGH 176-191 is the last 16 amino acids of growth hormone and starts with phenylalanine; AOD-9604 has tyrosine in that first position and is otherwise identical. They are close relatives, not the same substance, and all of the human trials used AOD-9604. Supplier listings add to the confusion: the FDA found suppliers giving AOD-9604 a different CAS number and structures that do not match its sequence.

Neither is growth hormone. Full growth hormone is a protein of 191 amino acids that acts on the growth-hormone receptor and raises IGF-1, and as somatropin it is an approved medicine. AOD-9604 is a piece of it that did not raise IGF-1 in the trials and has no approved use. In sport the distinction does not help: growth hormone and its fragments fall under the same WADA class, S2.2.3.

Frequently asked questions

Does AOD-9604 work for fat loss?

Not in people, as far as the trials show. It slowed weight gain in obese rodents, and a 12-week trial in 300 adults hinted at a small effect that was not statistically significant. The decisive trial, in which 502 randomised adults took it by mouth for 24 weeks alongside diet and exercise, found no significant difference from placebo, and the developer abandoned it for obesity in 2007. No trial has tested the injections sold today.

Is AOD-9604 the same as HGH fragment 176-191?

No, although they differ by only one amino acid. The natural fragment hGH 176-191 starts with phenylalanine; AOD-9604 has tyrosine there and is otherwise identical. Product listings often confuse the two, and the FDA found suppliers giving AOD-9604 the wrong CAS number. The human trials all used AOD-9604.

Is AOD-9604 legal in the Netherlands?

It is not a registered medicine in the Netherlands or anywhere else, so it may not be sold, advertised or supplied for use in people. Buying and selling it as research material is a different status, which our guide on research-use-only products in the Netherlands explains. The US GRAS determination has no legal effect in the EU. For athletes under anti-doping rules it is prohibited regardless of how it was obtained.

Is AOD-9604 FDA-approved or GRAS?

It is not an approved drug, and FDA advisers voted 12 to 0 in December 2024 against letting pharmacies compound it. The GRAS label dates from 2012, when an expert panel hired by the company judged it safe as a food ingredient; the company called the determination self-affirmed, it was never submitted to the FDA, and it covers food use only, not injections.

Is AOD-9604 banned in sport?

Yes, at all times, in and out of competition. The WADA Prohibited List names AOD-9604 in class S2.2.3 as an example of a growth-hormone fragment, and the Dutch anti-doping rules apply the same list. An Australian Crime Commission report on drugs in sport listed it among the peptides supplied to athletes. See our guide on peptides and the doping list.

Is AOD-9604 safe?

For oral and intravenous use for up to 24 weeks, the company's trials in 893 people found side effects at placebo level, mostly headache and stomach complaints, and no rise in IGF-1 or blood sugar. That record does not settle the question for injections under the skin, which were never tested and after which no one has measured blood levels. The FDA points to possible immune reactions, impurities in compounded peptides and serious events with unclear causality, including four cancers in the 12-week trial.

Storage and handling

Store according to product-label instructions and batch handling notes. Lyophilized research peptides are commonly kept dry, protected from light, and handled with clean laboratory technique.

References

Checked against these sources on 28 October 2026.

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