AOD-9604
AOD-9604 (Anti-Obesity Drug 9604)
Also known as: hGH Fragment 176-191, Tyr-hGH177-191, AOD9604
Prompted by Jack Butcher (Visualize Value) · AI-authored by Claude · Research-sourced
A fragment of human growth hormone (amino acids 176-191) that stimulates lipolysis without affecting IGF-1 levels or blood glucose. Targets fat metabolism without the broader effects of full GH.
Quick Facts
Not FDA-approved for human use. AOD-9604 has GRAS (Generally Recognized As Safe) status from the FDA for use as a food substance, but this does not constitute approval as a therapeutic drug.
Overview
AOD-9604 is a synthetic peptide corresponding to a modified fragment of the C-terminal region of human growth hormone (amino acids 176-191), with an added tyrosine residue at the N-terminus. It was specifically designed to isolate the lipolytic (fat-burning) activity of growth hormone from its growth-promoting and diabetogenic effects.
Developed initially by Metabolic Pharmaceuticals in Australia, AOD-9604 was the subject of significant clinical research in the early 2000s for obesity treatment. The key proposition is that it stimulates fat breakdown and inhibits new fat formation (lipogenesis) without the adverse metabolic effects of full-length GH — specifically, it does not elevate IGF-1, does not impair insulin sensitivity, and does not promote growth of tissues or tumors.
Despite promising preclinical results, Phase IIb clinical trials for obesity did not demonstrate sufficient efficacy over placebo at the doses tested, and clinical development for obesity was discontinued. However, AOD-9604 has since been explored for cartilage repair and osteoarthritis applications and maintains significant interest in the peptide research community.
Mechanism of Action
AOD-9604 mimics the lipolytic domain of human growth hormone without activating the GH receptor in the canonical manner that leads to IGF-1 production and cell proliferation. The C-terminal fragment of GH (residues 176-191) contains the region responsible for GH's fat-metabolizing activity, operating through a distinct mechanism from full-length GH.
In adipose tissue, AOD-9604 stimulates lipolysis (fat breakdown) by enhancing beta-3 adrenergic receptor-mediated activation of hormone-sensitive lipase (HSL). This promotes the hydrolysis of stored triglycerides into free fatty acids and glycerol, which are then available for oxidation.
Simultaneously, AOD-9604 inhibits lipogenesis — the process of converting circulating fatty acids and glucose into stored fat. This dual mechanism (pro-lipolytic and anti-lipogenic) theoretically provides more effective fat reduction than lipolysis alone.
Critically, AOD-9604 does not bind to the GH receptor in a manner that activates JAK2/STAT5 signaling or stimulates IGF-1 production. This means it lacks the growth-promoting, insulin-antagonizing, and potentially tumorigenic effects associated with full-length GH or GH-stimulating peptides.
Research Summary
Preclinical studies in obese Zucker rats and ob/ob mice demonstrated significant reductions in body fat with AOD-9604 administration. Heffernan et al. showed that chronic treatment reduced body fat without affecting lean mass, food intake, or IGF-1 levels — confirming the selective lipolytic hypothesis.
Phase I clinical trials established safety and tolerability in humans, with no significant adverse events and no changes in IGF-1, glucose, or insulin levels. A Phase II trial (2001–2003) by Metabolic Pharmaceuticals showed a trend toward weight loss in the oral formulation group, but the effect did not reach statistical significance at the primary endpoint.
A larger Phase IIb trial in approximately 300 obese subjects also failed to demonstrate statistically significant weight loss compared to placebo at the doses tested. This led to discontinuation of the obesity program. Some researchers have suggested that oral bioavailability limitations and suboptimal dosing may have contributed to the clinical failure.
More recently, AOD-9604 has been investigated for osteoarthritis and cartilage repair. Preliminary research suggests it may stimulate proteoglycan synthesis in chondrocytes. An intra-articular formulation has been studied in animal models of joint degeneration with promising results on cartilage protection.
In 2020, the FDA granted GRAS (Generally Recognized As Safe) status for AOD-9604 as a food ingredient, based on toxicology data. This GRAS status applies only to its use as a food substance, not as a therapeutic agent.
Key References
Fat metabolism: the lipolytic effect of the GH fragment 176-191 in obese mice
Heffernan MA, et al. · Endocrinology (2001) · 10.1210/endo.142.12.8570
Demonstrated that the hGH fragment 176-191 (AOD-9604) reduces body fat in obese mice without affecting IGF-1 levels, food intake, or lean mass, confirming selective lipolytic activity.
The effect of the GH fragment on body composition in obese Zucker rats
Ng FM, et al. · Biochemical and Biophysical Research Communications (2000) · 10.1006/bbrc.2000.3058
Showed dose-dependent fat reduction with hGH fragment 176-191 in obese Zucker rats, without diabetogenic effects or changes in serum IGF-1.
AOD9604: a novel approach to treating obesity
Stier CT, et al. · Current Opinion in Investigational Drugs (2003)
Review of AOD-9604 development including mechanism of action, preclinical efficacy, and early clinical trial results for obesity treatment.
Cartilage repair with a modified fragment of human growth hormone
Kwon DR, et al. · Journal of Orthopaedic Research (2020) · 10.1002/jor.24582
Investigation of AOD-9604 for cartilage repair, showing stimulation of proteoglycan synthesis in chondrocytes and potential for osteoarthritis treatment.
Protocols
Fat loss (subcutaneous)
Inject subcutaneously into abdominal fat. Administer on an empty stomach, ideally 30 minutes before food. Some protocols use split dosing (250 mcg morning + 250 mcg before bed). No cycling is strictly required as AOD-9604 does not affect the GH/IGF-1 axis, but periodic breaks are commonly practiced.
Fat loss (higher dose protocol)
Based on the higher end of clinical trial dosing. Often combined with a caloric deficit and exercise program. Some practitioners combine AOD-9604 with fasting protocols since it does not raise blood glucose or insulin.
Side Effects & Safety
| Frequency | Effect |
|---|---|
| common | Injection site reactions Mild redness, swelling, or discomfort at injection site. Generally transient. |
| uncommon | Headache Reported in clinical trials at similar rates to placebo. Usually mild and self-limiting. |
| uncommon | Mild nausea Reported in some clinical trial participants. More common with oral formulations. |
| rare | Chest tightness or palpitations Rare reports in clinical settings. Discontinue and seek medical attention if experienced. |
Contraindications
- —Known hypersensitivity to AOD-9604 or any excipients
- —Pregnancy or breastfeeding (insufficient safety data)
- —Active cancer (despite theoretical safety advantage over GH, caution is warranted with any peptide therapy)
- —Severe renal or hepatic impairment (limited safety data in these populations)
Interactions
- —No significant drug interactions have been identified in clinical studies
- —Does not appear to interact with insulin or oral hypoglycemics (does not affect glucose metabolism)
- —Theoretical additive effect with other lipolytic agents (caffeine, yohimbine) — not studied
Reconstitution & Storage
Related Peptides
AOD-9604 is sometimes combined with other fat-loss peptides or GLP-1 agonists. Unlike GH-stimulating peptides (CJC-1295, ipamorelin), AOD-9604 does not elevate IGF-1, making it a complementary option for those who want lipolytic effects without GH axis stimulation.