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AOD-9604 peptide research starts with a clean engineering idea: can you keep only the fat-mobilizing tail of human growth hormone and leave the rest of the hormone behind? AOD-9604 is a synthetic 16-amino-acid fragment modeled on the C-terminal end of human growth hormone (hGH), developed in Australia in the 1990s as an anti-obesity drug candidate. It is one of the few research peptides with a genuinely large human trial record — six randomized, placebo-controlled trials and 925 participants — and that record is unusually instructive, because it separates two questions that marketing copy often blends together: the compound was remarkably well tolerated, and it still failed its decisive efficacy test. This profile covers what AOD-9604 is, how its proposed mechanism differs from full-length growth hormone, what the animal and human studies actually found, the later cartilage research, and where the compound stands with regulators today. Researchers sourcing the compound can find the AOD-9604 research peptide in the Apex catalog, supplied strictly for laboratory research use.
AOD-9604 was developed by researchers at Monash University in Melbourne — in the laboratory of Frank Ng — and commercialized by Metabolic Pharmaceuticals. The name itself is a program code: AOD stands for Anti-Obesity Drug. The design logic came from mapping work on hGH showing that the hormone’s lipolytic (fat-reducing) activity is concentrated in its final C-terminal segment, while its growth-promoting and diabetogenic (blood-sugar-raising) activities live elsewhere in the 191-amino-acid protein.
| Property | Value |
|---|---|
| Sequence | Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe |
| Synonyms | AOD9604, modified hGH fragment 176–191, Tyr-hGH 177–191 |
| Molecular formula | C78H123N23O23S2 |
| Molecular weight | 1815.1 g/mol |
| CAS number | 221231-10-3 |
| PubChem CID | 71300630 |
| Structure | 16 amino acids, one intramolecular disulfide bond (Cys–Cys) |
| FDA approval status | Not FDA-approved for any indication |
| Research class | Growth hormone fragment / lipolysis research compound |
A note on numbering, because the literature uses two conventions: AOD-9604 is commonly described as hGH residues 176–191, and in the primary safety paper (Stier, Vos and Kenley, Journal of Endocrinology and Metabolism, 2013) as Tyr-hGH 177–191. Both describe the same idea — the natural phenylalanine at the start of the fragment is replaced by a tyrosine, giving a 16-residue peptide that is a modified copy of the hGH tail rather than an exact slice of the hormone. That single substitution, plus the disulfide bond between its two cysteine residues, helps distinguish AOD-9604 analytically from unmodified hGH fragment 176–191, a point that matters when reading a certificate of analysis. For background on defined synthetic sequences like this one, see our guide to what peptides are.
The central claim of aod-9604 peptide research is independence from the classical growth hormone pathway. Full-length hGH binds the growth hormone receptor, raises IGF-1, promotes growth, and antagonizes insulin — which is why long-term hGH exposure is associated in the literature with glucose intolerance, fluid retention, and related effects. In the trial record summarized by Stier and colleagues, AOD-9604 did none of those things: serum IGF-1 did not change, and oral glucose tolerance testing showed no negative effect on carbohydrate metabolism. Whatever AOD-9604 does, the evidence indicates it does not do it by acting like growth hormone.
The most-cited mechanistic study is Heffernan and colleagues (Endocrinology, 2001; PMID 11713213), from the Monash group. In obese mice, chronic treatment with either hGH or AOD9604 reduced body weight gain and increased lipolysis, and AOD9604 increased expression of beta-3 adrenergic receptors in adipose tissue — receptors that, in rodent fat, drive fat breakdown. The decisive control was genetic: in beta-3 receptor knockout mice, the chronic lipolytic effect of AOD9604 was absent. That knockout result is the strongest single piece of mechanistic evidence in this literature, and also its clearest limitation: beta-3 adrenergic biology is far more prominent in rodent adipose tissue than in human adipose tissue, which is one proposed reason the striking mouse results translated weakly in people.
No specific AOD-9604 receptor has been definitively identified, and the beta-3 effect in mice appears to involve upregulating receptor expression rather than the peptide simply switching the receptor on. FDA reviewers made a version of this point in 2024, describing the substance as not well characterized physically and chemically. Preclinical work also reports inhibition of lipogenesis — the creation of new stored fat — alongside stimulation of lipolysis in adipose models, but the human mechanistic data are essentially the negative findings: no IGF-1 signal, no glucose signal, no antibody signal. Researchers should read AOD-9604’s mechanism as a rodent-supported hypothesis with a clean human safety readout, not as settled human pharmacology.
Before the human program, AOD9604 was studied in obese mouse and rat models, including ob/ob mice and Zucker rats. Across those studies, chronic administration increased fat oxidation and plasma glycerol (a standard marker that stored triglyceride is being broken down), reduced weight gain and white adipose mass, and did so without the hyperglycemia seen with full-length hGH. In isolated adipose tissue, the fragment was reported to stimulate lipolysis preferentially in fat from obese animals and to inhibit lipogenesis. Those results were strong enough to justify a full clinical development program — more than $50 million was invested, according to later company and review accounts — and they remain the reason the compound is still used as a laboratory tool for studying GH-fragment and adipocyte signaling, even after the drug program ended.
This is the section that decides how aod-9604 peptide research should be summarized, and it has two halves that must not be separated.
Stier, Vos and Kenley (2013) summarized the safety data from all six randomized, double-blind, placebo-controlled trials of oral AOD9604, conducted in Australia and the United Kingdom between 2001 and 2007 in a total of 925 subjects:
That is one of the cleaner pooled safety records for an experimental peptide of its era. It is also, by itself, not evidence that the compound works.
In a 12-week randomized trial in 300 obese adults, the lowest tested oral dose group (1 mg) showed the largest weight change — roughly 2.6 to 2.8 kg lost versus about 0.8 kg on placebo, as reported from that trial program — with no clear dose-response at higher doses. The decisive test was the later 24-week Phase IIb trial (METAOD006), which enrolled more than 530 clinically obese subjects across multiple Australian centers at lower daily doses. That trial did not meet its primary weight-loss endpoint: there was no statistically significant difference versus placebo. Metabolic Pharmaceuticals terminated development of AOD9604 as an obesity drug in 2007.
The honest synthesis is therefore narrow: AOD-9604 demonstrated biological activity and placebo-like tolerability in humans, but it did not demonstrate reproducible, clinically meaningful weight loss in the largest trial designed to test exactly that question. Any source presenting AOD-9604 as a proven fat-loss agent is going beyond its own trial record. For researchers, the program is a textbook case of why rodent lipolysis data and human efficacy are different claims — and of why a laboratory compound can remain scientifically interesting after its drug program ends.
A second, smaller line of aod-9604 peptide research emerged after the obesity program ended. In vitro work reported that AOD9604 increased proteoglycan and collagen production in bovine chondrocytes — the cells that build cartilage matrix. Kwon and Park (Annals of Clinical and Laboratory Science, 2015; PMID 26275694) then tested intra-articular AOD9604 in a collagenase-induced rabbit model of knee osteoarthritis, alone and combined with hyaluronic acid. The combination group showed the best outcomes — lower cartilage degeneration scores and shorter lameness than either treatment alone — and AOD9604 alone also performed better than saline on the reported measures.
That finding is genuinely interesting as tissue research, and it is also exactly one animal study, with no human joint trial behind it. It should be cited as a preclinical cartilage signal that motivated further interest in the fragment’s non-metabolic activity — not as evidence for any joint application in people.
| Feature | AOD-9604 | Full-length hGH | Unmodified hGH fragment 176–191 |
|---|---|---|---|
| Size | 16 amino acids, ~1815 Da | 191 amino acids, ~22 kDa | 16 amino acids |
| N-terminal residue | Tyrosine (substituted) | Full hormone sequence | Phenylalanine (native) |
| Acts via GH receptor / raises IGF-1 | No IGF-1 effect in trials | Yes | Not established in human trials |
| Effect on glucose metabolism in trials | None detected | Can impair glucose tolerance | No comparable human dataset |
| Human RCT record | 6 trials, 925 subjects; pivotal trial negative | Extensive, approved for specific indications | No comparable RCT program |
| FDA-approved | No | Yes, for defined indications (as somatropin products) | No |
The comparison explains AOD-9604’s lasting research role: it is a defined, human-tested fragment for probing which of growth hormone’s effects can be separated from the hormone itself — a structure-activity question that remains useful in vitro regardless of the obesity program’s outcome.
AOD-9604 is not approved by the FDA, the EMA, the Australian TGA, or any other major regulator for any indication, and no approved medicine contains it. Its U.S. compounding history has moved several times, so dates matter:
AOD-9604 therefore has no current lawful 503A compounding pathway and remains an unapproved investigational compound in the United States. In sport, WADA prohibits it at all times under Section S2 as a growth hormone fragment (AOD-9604 / hGH 176–191 are named in anti-doping detection literature, and doping-control methods for the peptide were published as early as 2015 by Cox and colleagues in Drug Testing and Analysis). Tested athletes should treat it as prohibited without exception.
For laboratory work, AOD-9604’s history creates specific verification points:
No. It is a small synthetic fragment modeled on the C-terminal tail of human growth hormone. In human trials it did not raise IGF-1 and did not reproduce hGH’s negative effects on glucose metabolism — and it also did not reproduce a convincing weight-loss effect in its pivotal trial. It should never be described as growth hormone or as a substitute for it.
Strong lipolysis signals in obese rodents, linked in mice to beta-3 adrenergic receptor upregulation; a six-trial human safety record in 925 subjects that was indistinguishable from placebo, with no IGF-1, glucose, or antibody signal; one positive early 12-week weight signal that the larger 24-week Phase IIb trial did not confirm, ending drug development in 2007; and one preclinical rabbit study suggesting cartilage effects when combined with hyaluronic acid.
No. It is not FDA-approved for any indication, it is not on the 503A Bulks List — the PCAC voted 12–0 against inclusion in December 2024 — and no approved drug product contains it.
Because its parent program was designed to isolate hGH’s lipolytic segment, and rodent studies did show increased lipolysis and reduced fat gain. The nickname describes the design intent and the animal data. It omits the human result: the pivotal obesity trial missed its primary endpoint.
By HPLC for purity and mass spectrometry for identity against the expected molecular weight of 1815.1 Da, with attention to the N-terminal tyrosine that distinguishes AOD-9604 from the unmodified 176–191 fragment and to the integrity of its disulfide bond. The salt form and net peptide content should also be stated.
Related in the Apex shop: AOD-9604 research peptide — supplied strictly for laboratory research use.
Disclaimer: This article is for educational and laboratory research purposes only. AOD-9604 sold by Apex Bio Industries is a research-use-only (RUO) material, supplied strictly for in vitro and laboratory research. It is not approved by the FDA for human or veterinary use, is not a drug, supplement, or cosmetic, and nothing in this article is a claim of efficacy, a dosing recommendation, or an instruction for use in humans or animals.
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