AOD-9604: el fragmento modificado de hormona de crecimiento para la investigación del metabolismo de grasas

For informational purposes only. This article does not constitute medical advice. Consult a qualified healthcare provider for any health-related decisions.

What Is AOD-9604?

AOD-9604 (Anti-Obesity Drug 9604) is a synthetic peptide analog derived from the C-terminal region of human growth hormone (hGH). Specifically, it corresponds to amino acids 177-191 of the hGH sequence with an additional tyrosine residue added at the N-terminus. This modification was designed to stabilize the peptide and enhance its biological activity. The compound was originally developed by Metabolic Pharmaceuticals Limited (Melbourne, Australia) in collaboration with Monash University researchers who sought to isolate the fat-metabolizing properties of growth hormone from its other systemic effects, particularly the growth-promoting and diabetogenic actions mediated through IGF-1.

The fundamental premise behind AOD-9604 is that the C-terminal fragment of growth hormone contains the molecular region responsible for GH's lipolytic activity, and that this region can function independently of the full-length hormone. By using only this fragment (with minor modifications), researchers aimed to promote fat metabolism without elevating IGF-1 levels, altering blood glucose, or producing the other systemic effects associated with growth hormone administration.

Property	Detail
Name	AOD-9604 (Anti-Obesity Drug 9604)
Origin	Modified C-terminal fragment of hGH (aa 177-191) + N-terminal tyrosine
Developer	Metabolic Pharmaceuticals / Monash University
Molecular Weight	Approximately 1,817 Da
Administration (Research)	Subcutaneous injection; oral formulations studied
Mechanism	Lipolysis stimulation, lipogenesis inhibition
IGF-1 Effects	Does not stimulate IGF-1 production
Glucose Effects	Does not appear to affect blood glucose levels
FDA Status	Not approved as a drug; GRAS status for food use

Mechanism of Action

AOD-9604's mechanism of action centers on its interaction with fat metabolism pathways. Research has identified several key aspects of how the peptide may influence lipid homeostasis:

• Lipolysis stimulation: AOD-9604 has been shown in preclinical studies to stimulate the release of stored fat (triglycerides) from adipocytes through activation of beta-3 adrenergic receptor-associated pathways. This promotes the breakdown of fat into free fatty acids and glycerol for use as energy substrates.
• Lipogenesis inhibition: In addition to promoting fat breakdown, AOD-9604 appears to inhibit the formation of new fat (lipogenesis) by reducing the activity of enzymes involved in fatty acid synthesis within adipose tissue.
• No IGF-1 elevation: Unlike full-length growth hormone, AOD-9604 does not bind the GH receptor in a manner that activates the JAK-STAT signaling pathway responsible for IGF-1 production. This is a critical distinction, as IGF-1 elevation is responsible for many of GH's growth-promoting and potentially problematic effects.
• No glucose perturbation: Clinical studies have not observed significant changes in fasting glucose, insulin, or glucose tolerance with AOD-9604 administration, addressing one of the major safety concerns associated with GH therapy.

The exact receptor or binding target through which AOD-9604 exerts its lipolytic effects has not been fully characterized. Some research suggests it may interact with a distinct site on the GH receptor complex or with an as-yet-unidentified receptor involved in fat metabolism signaling. This mechanistic uncertainty remains an area of ongoing investigation.

Research Landscape

Preclinical Studies

Early preclinical research conducted at Monash University demonstrated that the hGH fragment 177-191 and its modified form AOD-9604 could reduce body fat in obese animal models (ob/ob mice) without affecting lean mass or overall growth. These studies showed dose-dependent reductions in fat mass, increased fat oxidation, and no effects on blood glucose or IGF-1 levels. The preclinical data were encouraging and supported the hypothesis that GH's lipolytic domain could be therapeutically exploited in isolation.

Clinical Trials

Metabolic Pharmaceuticals conducted several clinical trials evaluating AOD-9604 for obesity:

• Phase 1 studies: Established safety and tolerability at various dose levels. No significant adverse events were reported, and IGF-1 and glucose levels remained unaffected.
• Phase 2 studies: Showed some evidence of modest weight loss in obese individuals. One study demonstrated a statistically significant reduction in body weight compared to placebo over 12 weeks, though the magnitude of the effect was modest.
• Phase 2b/3 study: A larger trial failed to demonstrate statistically significant weight loss at the primary endpoint. Despite trends toward fat reduction, the results did not meet the threshold required for regulatory advancement as an obesity drug.

The failure of the larger clinical trial to meet its primary endpoint effectively ended the pharmaceutical development of AOD-9604 as an obesity treatment. Metabolic Pharmaceuticals subsequently shifted focus, and the compound did not progress to Phase 3 registration trials.

Key Studies

Despite the clinical disappointment for obesity, AOD-9604 has generated interest in other research areas. Studies have explored its potential effects on cartilage repair, with some preclinical evidence suggesting that the peptide may promote chondrocyte activity and cartilage regeneration. This line of research is distinct from the original metabolic application and remains preliminary. AOD-9604 received GRAS (Generally Recognized as Safe) status from the FDA for use as a food ingredient, which is a regulatory classification distinct from drug approval and does not imply efficacy for any therapeutic purpose.

Safety Profile

The clinical safety data for AOD-9604 is generally reassuring, though limited in scope and duration:

Parameter	Finding
IGF-1 Levels	No significant changes observed
Blood Glucose	No significant changes observed
Insulin Sensitivity	No adverse effects on insulin sensitivity
Common Side Effects	Mild injection site reactions, headache (similar to placebo rates)
Serious Adverse Events	None attributed to the compound in clinical trials
Antibody Formation	Low immunogenicity reported

It is important to note that the available safety data comes from relatively short-duration clinical trials. Long-term safety data for AOD-9604 is limited, and the compound has not undergone the extensive post-marketing surveillance that accompanies FDA-approved drugs.

Comparison to Related Compounds

AOD-9604 is closely related to the unmodified HGH Fragment 176-191, which represents the native C-terminal fragment of growth hormone without the additional N-terminal tyrosine modification. The addition of the tyrosine residue in AOD-9604 was intended to improve stability and bioactivity. Both compounds share the same fundamental mechanism of promoting lipolysis through the GH fragment domain, but AOD-9604 is the version that has undergone formal clinical development.

Compared to full-length growth hormone, AOD-9604 offers a theoretical advantage in selectively promoting fat metabolism without the growth-promoting, diabetogenic, or IGF-1-elevating effects of GH. However, its clinical efficacy for weight loss has not been established at a level comparable to modern agents like GLP-1 receptor agonists. For related research on fat metabolism peptides, see our article on Fat Loss Peptides: AOD-9604 and HGH Fragment.

Current Status

AOD-9604 is not approved as a drug by any major regulatory authority. It holds GRAS status for food applications in the United States. The compound is widely available through research peptide suppliers and has gained popularity in the peptide research community despite the lack of approved therapeutic indications. Its appeal lies primarily in its favorable safety profile relative to full-length growth hormone and the theoretical selectivity for fat metabolism. Researchers and individuals should be aware that the clinical evidence for meaningful fat loss with AOD-9604 is limited, and the compound remains investigational from a therapeutic standpoint.