AOD-9604
Advanced Obesity Drug 9604
Regulatory Status
Not FDA-approved for any therapeutic indication. Classified as a research chemical. The FDA has not specifically scheduled AOD-9604, but it is not approved for human use and may be subject to future regulatory action under the peptide reclassification framework.
FDA · Updated Mar 2026
Available for research purposes. Not licensed as a medicinal product under MHRA regulations. The Human Medicines Regulations 2012 do not specifically schedule AOD-9604, but sale for human consumption without marketing authorisation is unlawful.
MHRA · Updated Mar 2026
AOD-9604 has received TGA registration and is available via prescription. Australia is one of the few jurisdictions where this peptide has achieved formal regulatory recognition, with specific approved indications. Available through compounding pharmacies with a valid prescription.
TGA · Updated Mar 2026
Prohibited at all times as a growth hormone fragment under WADA S2 category.
WADA · Updated Jan 2026
What Is AOD-9604?
AOD-9604, or Advanced Obesity Drug 9604, is a synthetic peptide fragment derived from the C-terminal region of human growth hormone (hGH). Specifically, it corresponds to amino acids 176 through 191 of the hGH molecule, with the addition of a tyrosine residue at the N-terminus for stability. The resulting 16-amino-acid peptide has a molecular weight of approximately 1815.08 Da.
The peptide was originally developed in the 1990s by researchers at Monash University in Melbourne, Australia, led by Professor Frank Ng. The rationale behind AOD-9604 was elegantly simple: growth hormone is known to possess potent lipolytic (fat-burning) properties, but full-length GH also carries significant metabolic side effects, including insulin resistance, fluid retention, and potential proliferative effects. Researchers hypothesised that the fat-metabolising activity of GH could be isolated to a specific fragment of the molecule, separating the desired lipolytic effects from the unwanted side effects.
This approach — extracting a functional fragment from a larger hormone — represented an innovative strategy in peptide therapeutics. AOD-9604 was designed to retain the fat-metabolising properties of growth hormone while avoiding its diabetogenic and growth-promoting effects.
How AOD-9604 Works
Mechanism of Action
The mechanism of action of AOD-9604 is distinct from full-length growth hormone in several important ways. Research suggests that AOD-9604 stimulates lipolysis (the breakdown of stored fat) and inhibits lipogenesis (the formation of new fat) through pathways that do not involve the GH receptor in the same manner as intact growth hormone.
Studies indicate that AOD-9604 may act through a mechanism involving the beta-3 adrenergic receptor pathway, which plays a central role in regulating fat metabolism in adipose tissue. Unlike full-length GH, AOD-9604 does not appear to bind to the classical GH receptor or stimulate IGF-1 production. This is a critical distinction because IGF-1 elevation is responsible for many of the proliferative and metabolic side effects associated with GH therapy.
In preclinical models, AOD-9604 has been shown to stimulate lipolysis in a manner similar to the full GH molecule while demonstrating no effect on blood glucose levels or insulin sensitivity at the doses studied. This suggests that the lipolytic domain of GH can function independently of the domains responsible for glucose counter-regulation.
Fat Metabolism Pathways
The lipolytic activity of AOD-9604 appears to involve stimulation of hormone-sensitive lipase (HSL) activity in adipocytes. HSL is the rate-limiting enzyme in the mobilisation of stored triglycerides from fat cells. By enhancing HSL activity, AOD-9604 may promote the release of free fatty acids from adipose tissue, making them available for oxidation as an energy source.
Additionally, research suggests that AOD-9604 may inhibit lipogenic enzymes, including fatty acid synthase and acetyl-CoA carboxylase, thereby reducing the rate at which new fatty acids are synthesised and stored. This dual mechanism — enhanced fat breakdown coupled with reduced fat synthesis — may explain the body composition changes observed in preclinical studies.
Research and Clinical Evidence
Fat Metabolism and Weight Management
The most substantial body of evidence for AOD-9604 relates to its effects on fat metabolism. Early preclinical studies conducted at Monash University demonstrated that AOD-9604 reduced body fat in obese mice without affecting lean mass, food intake, or blood glucose levels [1]. These animal studies showed dose-dependent reductions in body weight, primarily driven by reductions in adipose tissue mass.
A Phase IIb clinical trial in obese humans was conducted by Metabolic Pharmaceuticals Limited in the early 2000s. The trial enrolled over 300 participants and evaluated oral AOD-9604 at various doses over 12 weeks. While the peptide demonstrated a favourable safety profile and some positive trends in weight reduction, the primary efficacy endpoint was not met with statistical significance [2]. This trial outcome was a significant setback for the clinical development programme and contributed to the company ultimately ceasing development.
However, the safety data from this trial are noteworthy. AOD-9604 did not produce the adverse metabolic effects associated with full-length GH, including changes in fasting glucose, insulin levels, or IGF-1 concentrations. This supports the hypothesis that the lipolytic fragment can be separated from the metabolic side-effect profile of intact GH.
Cartilage Repair and Osteoarthritis
An unexpected and promising area of research for AOD-9604 emerged from studies examining its effects on cartilage tissue. Preclinical research conducted by Metabolic Pharmaceuticals and later by other groups demonstrated that AOD-9604 may stimulate proteoglycan and collagen synthesis in chondrocytes [3].
In vitro studies showed that AOD-9604 enhanced the proliferation of chondrocytes and stimulated the production of extracellular matrix components essential for cartilage integrity. Animal models of osteoarthritis treated with intra-articular AOD-9604 injections showed improvements in cartilage structure and reduced markers of cartilage degradation compared to controls.
These findings led to the development of AOD-9604 as a potential treatment for osteoarthritis, with clinical trials conducted in Australia evaluating intra-articular injection for knee osteoarthritis. Preliminary results from these studies suggest potential benefits for joint function and pain reduction, though large-scale confirmatory trials are still needed.
Bone and Musculoskeletal Effects
Separate from its cartilage effects, some preclinical research has explored whether AOD-9604 may influence bone metabolism. Studies in animal models suggest that AOD-9604 may support osteoblast activity and bone mineral density without the proliferative risks associated with full-length GH or IGF-1. However, this area of research remains in its early stages, and human data are not yet available.
Dosage Information
The following dosage information is derived from published clinical and preclinical research and is provided for educational purposes only. This is not a prescribing recommendation.
In the Phase IIb obesity trial, oral doses of AOD-9604 ranged from 1 mg to 50 mg daily. The subcutaneous dosing protocols most commonly referenced in the research literature involve doses of 250 mcg to 300 mcg administered once daily, typically in the morning in a fasted state.
The rationale for fasted administration relates to the peptide’s mechanism of action. Since AOD-9604 is thought to stimulate lipolysis, administering it during a fasted state — when insulin levels are low — may theoretically enhance its fat-mobilising effects, as insulin is a potent inhibitor of hormone-sensitive lipase.
For intra-articular administration in osteoarthritis research, doses of 1.2 mg to 2.4 mg per injection have been studied, with varying treatment frequencies.
It is important to note that optimal dosing for AOD-9604 has not been definitively established for any indication, as the peptide has not completed Phase III clinical development for its metabolic applications.
Side Effects and Safety Considerations
One of the most notable aspects of AOD-9604 is its favourable safety profile in published studies. In the Phase IIb clinical trial involving over 300 participants, the adverse event profile was comparable to placebo. Key safety findings include:
- No effect on blood glucose: Unlike full-length GH, AOD-9604 did not alter fasting glucose or insulin sensitivity at the doses studied
- No IGF-1 elevation: AOD-9604 did not increase serum IGF-1 levels, suggesting absence of proliferative growth effects
- No significant fluid retention: Unlike GH therapy, clinically significant oedema was not reported
- Injection site reactions: Mild redness or discomfort at injection sites, resolving spontaneously
- Headache: Reported at rates comparable to placebo
- Gastrointestinal discomfort: Mild nausea or stomach upset reported occasionally with oral formulations
The absence of IGF-1 elevation is particularly significant from a safety perspective, as it suggests that AOD-9604 may not carry the theoretical cancer risk associated with sustained IGF-1 elevation seen with full GH therapy or GH secretagogues.
Despite the favourable short-term safety data, long-term safety studies spanning years of continuous use have not been conducted. As with any peptide lacking full regulatory approval, users should exercise caution and seek medical supervision.
Frequently Asked Questions
How is AOD-9604 different from HGH?
AOD-9604 is a fragment of the human growth hormone molecule, consisting of only amino acids 176-191 plus a stabilising tyrosine residue. Unlike full HGH, research suggests it does not bind to the classical GH receptor, does not elevate IGF-1 levels, and does not appear to affect blood glucose or insulin sensitivity. It is designed to isolate the fat-metabolising properties of GH while avoiding its broader metabolic side effects.
Why did clinical trials for obesity not succeed?
The Phase IIb trial did not meet its primary efficacy endpoint for statistically significant weight loss compared to placebo, despite showing positive trends. Several factors may have contributed, including the oral formulation used (which may have reduced bioavailability), the dose range selected, and the 12-week study duration, which may have been insufficient to detect meaningful body composition changes.
Is AOD-9604 approved anywhere in the world?
AOD-9604 has achieved regulatory recognition in Australia, where it has received TGA registration and is available via prescription through compounding pharmacies. Australia remains one of the few jurisdictions where this peptide has formal regulatory status. It is not approved by the FDA, MHRA, or most other regulatory agencies.
Can athletes use AOD-9604?
No. AOD-9604 is included on the World Anti-Doping Agency (WADA) prohibited list under category S2 — Peptide Hormones, Growth Factors, Related Substances and Mimetics. Its use is prohibited in competition and out of competition for all athletes subject to WADA anti-doping rules.
Does AOD-9604 affect muscle growth?
Unlike full-length growth hormone, AOD-9604 does not appear to promote significant muscle hypertrophy based on available evidence. It does not elevate IGF-1, which is a primary mediator of GH’s anabolic effects on muscle tissue. Its primary researched activity relates to fat metabolism and, more recently, cartilage repair.
References
- Ng FM, Sun J, Sharma L, Libinaka R, Jiang WJ, Gianello R. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res. 2000;53(5):274-278.
- Metabolic Pharmaceuticals Limited. Phase IIb clinical trial results for AOD-9604 in obesity. ASX Announcement. 2007.
- Yuen A, Layton G, Gianello R, et al. rHGH 176-191 stimulates proteoglycan synthesis in chondrocytes. J Bone Miner Res. 2006;21(Suppl 1):S424.
- Heffernan M, Jiang WJ, Thorburn AW, Ng FM. Effects of oral administration of a synthetic fragment of human growth hormone on lipid metabolism. Am J Physiol Endocrinol Metab. 2000;279(3):E501-E507.
Continue Reading