1. What is it?
AOD-9604 is a synthetic peptide developed from a human growth hormone fragment. The aim was to use an action related to fat metabolism without reproducing the hormone's full effects. This was a hypothesis, not guaranteed effectiveness. A hormone fragment is not a weaker, automatically safe version. The separate molecule needs its own evidence on effects, processing in the body and risks. [177] [175]
2. Why do people turn to it?
Interest in AOD-9604 most often relates to reducing body fat. Cartilage repair is another topic. These goals must be assessed separately: a joint experiment does not demonstrate weight loss, and a metabolic change in mice does not confirm repair of a human knee. Human weight-loss studies have been conducted, but did not provide the hoped-for confirmation of effectiveness. Cartilage research includes a rabbit model of joint disease. [177] [176]
3. How does it work?
In studies of obese mice, AOD-9604 affected processes involved in fat metabolism. Changes in body weight and fat tissue were observed during a short experiment. Such findings can suggest directions for further research, but do not replace measurements in humans. A mouse's body, follow-up duration and feeding conditions differ from the life of someone with long-standing obesity. An effect on fat breakdown alone also does not guarantee lasting weight reduction. [175]
4. What do studies actually show?
The OPTIONS programme randomly allocated 502 adults with obesity to study groups. According to the FDA assessment, it did not meet its planned effectiveness target for weight reduction. Development of AOD-9604 as an obesity medicine ended in 2007. For someone seeking weight loss, this matters more than a favourable mouse experiment. Failure in a large trial should not be ignored just because the proposed mechanism sounds convincing. [177]
5. What do we still not know?
A separate study involved 32 rabbits with experimentally induced knee osteoarthritis. Researchers assessed cartilage and movement after AOD-9604, including in combination with hyaluronic acid. The findings encouraged further research. However, they do not tell us whether a person with chronic knee pain would experience lasting improvement. An induced disease in an animal differs from years of damage to a human joint in its course, loading and accompanying conditions. Examining tissue under a microscope is useful, but patients also need better walking, less pain and lasting effects. This paper does not provide such clinical data. [176]
6. What are the risks?
The FDA notes that information for assessing AOD-9604 safety is limited, with potential concerns about immune reactions and impurities. It also records serious events whose causal relationship with the substance has not been established. It would therefore be wrong to claim either that AOD-9604 definitely caused them or that the risk has been ruled out. Safety findings for one formulation cannot freely be transferred to another, particularly when the route of administration differs. [174]
7. Is it an approved medicine?
AOD-9604 is not an FDA-approved obesity medicine. Assessing a compounding ingredient does not approve a treatment. Rabbit-cartilage research also does not authorize treatment of human joints. Here it remains an investigational substance, with failure of an important weight-loss programme and no basis for calling it a proven regenerative treatment. [177] [176]
8. What is new in research?
As of 3 November 2026, the reviewed sources contained no new large clinical trial overturning the earlier conclusion that convincing weight-loss effectiveness had not been demonstrated. The FDA assessment and the limitations of published experiments remain the relevant reference points. An old mouse or rabbit study does not become new evidence when it is described again. A breakthrough would require new human data showing lasting improvement and safety, rather than another explanation of a mechanism. [177] [175] [176]
Where does this information come from?
References link to the publications and documents used. Each source includes its material type and what was reviewed; findings concern the substance, form and study population described.
Show sources and how they were checked
- FDA Evaluation of AOD-9604-Related Bulk Drug Substances (AOD-9604 (free base) and AOD-9604 acetate)
FDA assessment dated 5 November 2024 for the PCAC meeting on 4 December 2024; identity, history of human studies, effectiveness and safety limitations reviewed. Accessed: 3 November 2026.
- The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice
Mouse study; December 2001; PubMed abstract read · DOI: 10.1210/endo.142.12.8522. Accessed: 03.11.2026.
- Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model
Study in 32 rabbits with experimentally induced joint disease; summer 2015; PubMed abstract reviewed. Accessed: 3 November 2026.
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks
FDA; page read on 03.11.2026; used the description of risks of injected GHK-Cu and AOD-9604, without drawing conclusions about current compounding eligibility. Accessed: 03.11.2026.