Notice: AOD9604 is not approved as a medicinal product in any country. Its development as an obesity drug was discontinued in 2007. This text is for information only and is based on published studies and assessments by regulatory authorities. Arion Bios products are intended exclusively for laboratory and research purposes. They are not medicines or dietary supplements and are not intended for use in humans or animals.

AOD9604 is one of the few research peptides that went through a complete clinical programme. Between 2001 and 2006, almost 900 people received it in randomised trials. Yet the programme ended in failure: the decisive trial did not show that people on AOD9604 lost more weight than those on placebo.

In this article we explain where the peptide came from, what it showed in animals, how the human trials turned out and what came after 2007. At the end you will find its regulatory status and how to identify AOD9604 in a certificate of analysis.

The key facts at a glance

  • What it is: a synthetic peptide of 16 amino acids. It is a modified end section of human growth hormone (amino acids 177–191) with an added tyrosine.
  • Origin: it came out of research at Monash University in Melbourne and was developed by the Australian company Metabolic Pharmaceuticals.
  • Animals: it increased fat breakdown and reduced weight gain without raising blood sugar or binding to the growth hormone receptor.
  • Humans: six randomised trials with 893 participants. The decisive OPTIONS trial showed no significant difference from placebo, and development as an obesity drug ended.
  • Regulation: not approved anywhere; the FDA advised against it for pharmacy compounding in 2024, and it is banned in sport.

Where AOD9604 came from

Human growth hormone (hGH) is a protein of 191 amino acids. Besides growth, it also influences fat metabolism and blood sugar. In the 1990s, Frank Ng’s team at Monash University investigated whether the effect on fat tissue could be separated from the hormone’s other effects and attributed to just a small part of the molecule.

In 1993 the team reported that a synthetic section of hGH covering positions 177–191 suppressed fat formation in rats. The researchers then stabilised this section by adding a tyrosine to the start of the chain. The result was a 16-amino-acid peptide designated AOD9604. According to a 2004 review, the Australian company Metabolic Pharmaceuticals developed and patented it in the late 1990s as a potential obesity drug.

Parameter Value
Sequence YLRIVQCRSVEGSCGF (Tyr + hGH 177–191)
Length 16 amino acids
Disulfide bridge Between the 7th and 14th amino acids (cysteine–cysteine)
Molecular formula C78H123N23O23S2
Molecular weight 1815.1 g/mol
Monoisotopic mass 1813.86 Da
Identifiers CAS 221231-10-3, PubChem CID 71300630

AOD9604 is often confused with HGH Fragment 176-191, from which it differs only in the first amino acid. We cover this in detail in AOD9604 vs Fragment 176-191: What Is the Difference?

What animal studies showed

Most of the mechanistic data were published around the turn of the millennium by the Monash University team. Three papers stand out:

  • Obese mice, oral administration (2000). Obese ob/ob mice received the peptide by mouth for 30 days. From day 16 they gained significantly less weight than the control group, even though they ate the same amount. In their fat tissue, fat breakdown sped up and fat formation slowed. The peptide had the same effect on isolated human fat tissue in the laboratory. In this paper the peptide is designated AOD-9401.
  • Obese rats (2000). Obese Zucker rats given AOD9604 for 19 days gained less than half as much weight as the control animals. Unlike whole growth hormone, the peptide did not impair insulin sensitivity.
  • Comparison with growth hormone (2001). Both the hormone and AOD9604 reduced weight gain in obese mice and increased fat burning. Unlike the hormone, however, AOD9604 did not raise blood sugar or reduce insulin secretion. It did not bind to the growth hormone receptor and did not stimulate the division of cells carrying that receptor.

Another 2001 study found that in mice lacking the beta-3 adrenergic receptor, the long-term effect on body weight did not appear. The receptor therefore probably contributes to the effect but is not its direct target. In its 2024 evaluation, the US Food and Drug Administration (FDA) concludes that the molecular target of AOD9604 remains unknown.

Human trials: from hope to disappointment

Between 2001 and 2006, six randomised, double-blind, placebo-controlled trials were conducted. In them, the company tested both intravenous and oral administration.

The first studies

A 2004 review describes three early studies in people with obesity: a four-week study with intravenous administration in 23 adults, a four-week study with oral administration in 16 men and a one-week study in 36 men. After administration, blood levels of free fatty acids rose, a sign of fat breakdown. None of the studies, however, showed statistically significant weight loss compared with placebo.

The phase 2 trial

A 12-week trial with 300 adults with obesity was published in 2005 only as a conference abstract. The authors reported slightly greater loss of weight and waist circumference than with placebo and an unusual dose–response relationship: the lowest dose worked best. The FDA noted that the differences from placebo were small, their practical relevance unclear, and the full results were never published.

The decisive OPTIONS trial

The phase 2b trial enrolled 536 adults with obesity and lasted 24 weeks. All participants, including the placebo group, followed a diet and exercise programme, much as they would in a phase 3 trial. On 21 February 2007, the company announced that the difference in weight loss compared with placebo did not reach statistical significance at either 12 or 24 weeks. It ended the development of AOD9604 as an obesity drug.

Safety

A summary of the safety data from all six trials was published in 2013. Adverse events were at placebo level, AOD9604 did not affect levels of IGF-1 (a hormone whose production is driven by growth hormone), and participants did not develop antibodies against the peptide. The authors were associated with the company, as they themselves disclose. In 2024, the FDA pointed to the limited extent of the published data and to a possible risk of an immune reaction, particularly with injectable forms.

What came after 2007

In the same 2007 announcement, the company said it would continue researching AOD9604 for osteoporosis. The published literature mainly offers a 2015 study in rabbits with artificially induced knee osteoarthritis. In it, the peptide given into the joint improved the state of the cartilage compared with the control group, and combined with hyaluronic acid it worked better than either substance alone. This is preclinical research in 32 animals.

Meanwhile, AOD9604 appeared in sport. A 2013 report by the Australian Crime Commission listed it among the peptides supplied to athletes. Unlabelled vials containing AOD9604 were found with elite athletes in Germany and Belgium, and in the US, laboratories detected it in confiscated samples. In 2024 the FDA also found that online offers link it to a wide range of uses, from joints and bones to ageing. There are no clinical studies to support these uses.

Regulation and sport

  • Approval: AOD9604 is not authorised as a medicine in any country. In 2024 the FDA found no monograph for it in the European, Chinese, Indian or Japanese pharmacopoeias.
  • US: in its November 2024 evaluation, the FDA proposed not to add AOD9604 to the list of substances pharmacies may use for compounding. The reasons were insufficient evidence of effectiveness and possible safety risks. AOD9604 is not among the six peptides that the US Department of Health and Human Services opened up to pharmacies in October 2026.
  • Australia: in its country of origin, the authorities have classified it among performance and image enhancing drugs that may not be possessed without authority, such as a prescription.
  • Sport: in 2013, WADA stated that AOD9604 had not been approved by any regulatory authority and therefore falls under prohibited non-approved substances. The current list names it among the growth hormone fragments in category S2. It is prohibited at all times.

How to identify AOD9604 in a certificate of analysis

What matters is mass spectrometry (MS), not just HPLC purity. The theoretical monoisotopic mass of AOD9604 is approximately 1813.9 Da. The doubly charged ion [M+2H]2+, the form in which peptides often appear in the spectrum, comes out at around m/z 908. The native Fragment 176-191, which starts with phenylalanine, is 16 Da lighter, so mass spectrometry reliably tells them apart. We explain how to read a certificate in Peptide Certificate of Analysis: How to Read a CoA.

What Arion Peptides offers

Our range includes AOD9604 5 mg as a lyophilised powder in a vial. Certificates of analysis for Arion Bios batches are available on the certificates of analysis page. The product is intended exclusively for laboratory and research purposes. An overview of the studies associated with the related peptide can be found in Fragment 176-191: Mechanism of Action and Study Overview.

Frequently Asked Questions

Is AOD9604 approved as a medicine?

No. It is not authorised in any country. Metabolic Pharmaceuticals ended its development as an obesity drug in 2007.

Why did the development of AOD9604 end?

The decisive OPTIONS trial with 536 participants did not show statistically significantly greater weight loss than placebo, at either 12 or 24 weeks.

Does AOD9604 act like growth hormone?

Not in the studies. It does not bind to the growth hormone receptor, does not stimulate cell division via that receptor and did not affect IGF-1 levels in clinical trials. In animals it mainly affected fat metabolism.

Is AOD9604 the same as Fragment 176-191?

Not quite. AOD9604 starts with tyrosine, the natural 176–191 section with phenylalanine. Otherwise the sequences are the same. However, products sold as Fragment 176-191 sometimes contain a sequence identical to AOD9604.

Is AOD9604 banned in sport?

Yes. The WADA Prohibited List names it among the growth hormone fragments in category S2. The ban applies at all times.

Summary

AOD9604 is a modified end section of growth hormone that, in animals, sped up fat breakdown and slowed weight gain without the typical adverse effects of the whole hormone. In humans it went through six randomised trials and was well tolerated. The decisive trial, however, did not show an effect compared with placebo, and development as an obesity drug ended in 2007.

Today AOD9604 remains a research substance without approval, with a small body of preclinical cartilage research and a ban in sport. For research, it is important to verify that a sample really contains this molecule. The answer comes from a certificate of analysis with mass spectrometry.

Sources

  1. Wu Z, Ng FM, “Antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone”, Biochemistry and Molecular Biology International, 1993;30(1):187–196: pubmed.ncbi.nlm.nih.gov
  2. Heffernan M, Jiang WJ, Thorburn AW, Ng FM, “Effects of oral administration of a synthetic fragment of human growth hormone on lipid metabolism”, American Journal of Physiology – Endocrinology and Metabolism, 2000;279(3):E501–E507. DOI: 10.1152/ajpendo.2000.279.3.E501
  3. Ng FM, Sun J, Sharma L et al., “Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone”, Hormone Research, 2000;53(6):274–278. DOI: 10.1159/000053183
  4. Heffernan MA, Thorburn AW, Fam B et al., “Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment”, International Journal of Obesity, 2001;25(10):1442–1449. DOI: 10.1038/sj.ijo.0801740
  5. Heffernan M, Summers RJ, Thorburn A et al., “The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and β3-AR knock-out mice”, Endocrinology, 2001;142(12):5182–5189. DOI: 10.1210/endo.142.12.8522
  6. Wilding J, “AOD-9604 Metabolic”, Current Opinion in Investigational Drugs, 2004;5(4):436–440: pubmed.ncbi.nlm.nih.gov
  7. Metabolic Pharmaceuticals Limited, “Metabolic’s obesity drug – Phase 2B clinical trial results”, announcement to the Australian Securities Exchange (ASX), 21 February 2007 (SEC archive): sec.gov
  8. Stier H, Vos E, Kenley D, “Safety and Tolerability of the Hexadecapeptide AOD9604 in Humans”, Journal of Endocrinology and Metabolism, 2013;3(1-2):7–15. DOI: 10.4021/jem157w
  9. Cox HD, Smeal SJ, Hughes CM, Cox JE, Eichner D, “Detection and in vitro metabolism of AOD9604”, Drug Testing and Analysis, 2015;7(1):31–38. DOI: 10.1002/dta.1715
  10. Kwon DR, Park GY, “Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model”, Annals of Clinical and Laboratory Science, 2015;45(4):426–432: pubmed.ncbi.nlm.nih.gov
  11. U.S. Food and Drug Administration, “FDA Evaluation of AOD-9604-Related Bulk Drug Substances”, briefing material for the Pharmacy Compounding Advisory Committee, 2024: fda.gov
  12. WADA, “WADA Statement on substance AOD-9604”, 24 April 2013 (reprinted by the International Weightlifting Federation): iwf.sport
  13. WADA, “The Prohibited List”, category S2: wada-ama.org
  14. PubChem, “AOD-9604, CID 71300630”: pubchem.ncbi.nlm.nih.gov