AOD-9604

Overview

AOD-9604 (Anti-Obesity Drug 9604) is a synthetic peptide corresponding to a modified fragment of human growth hormone (hGH), specifically the C-terminal region spanning amino acids 176 through 191. It was developed in the 1990s by Professor Frank Ng and colleagues at Monash University in Melbourne, Australia, based on the observation that the fat-metabolizing activity of growth hormone resides in a different region of the molecule than its growth-promoting and diabetogenic effects.

The core hypothesis behind AOD-9604 is that growth hormone's lipolytic (fat-burning) activity can be isolated from its other biological activities. Full-length hGH stimulates growth, increases IGF-1 levels, and can impair insulin sensitivity — side effects that limit its utility as an anti-obesity agent. AOD-9604 was designed to retain the fat-metabolizing properties while avoiding these unwanted effects.

The peptide was developed commercially by Metabolic Pharmaceuticals Ltd. (later acquired by Calzada Ltd.) and progressed through Phase II clinical trials for obesity. While early results showed promise, a large Phase IIb trial reported in 2007 failed to demonstrate statistically significant weight loss over placebo at 24 weeks, effectively ending its development as a pharmaceutical anti-obesity agent.

More recently, AOD-9604 has attracted attention for potential cartilage repair and osteoarthritic applications, with the compound receiving Generally Recognized as Safe (GRAS) status from the US FDA in 2020 as a food ingredient — an unusual regulatory pathway for a peptide.

Structure

AOD-9604 is a 16-amino-acid peptide with a tyrosine addition at the N-terminus:

Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe

• Molecular weight: ~1,817 g/mol
• CAS Number: 221231-10-3

Structural features:

• Corresponds to hGH amino acids 177–191 with an added N-terminal tyrosine (hence "Tyr-hGH177-191")
• Contains a disulfide bond between the two cysteine residues (Cys-182 and Cys-189 in full-length hGH numbering), forming a loop structure
• This disulfide loop is critical for biological activity — reduction of the bond abolishes lipolytic function
• The peptide lacks the regions of hGH responsible for GH receptor dimerization, IGF-1 stimulation, and growth-promoting effects

Mechanism of Action

Lipolysis Stimulation

AOD-9604's primary studied mechanism is the stimulation of fat breakdown (lipolysis) without activating the classical GH receptor signaling cascade:

• Mimics the lipolytic action of the C-terminal domain of hGH
• Stimulates lipolysis in adipose tissue through a mechanism that appears independent of the canonical GH receptor (GHR)
• Enhances beta-3 adrenergic receptor-mediated fat oxidation
• Increases fatty acid release from adipocytes
• The exact receptor or binding target mediating these effects has not been definitively identified

No IGF-1 Elevation

A critical distinction between AOD-9604 and full-length hGH:

• AOD-9604 does not activate the GH receptor in a manner that stimulates hepatic IGF-1 production
• No elevation of circulating IGF-1 levels has been observed in clinical studies
• This means AOD-9604 avoids the growth-promoting and potentially diabetogenic effects mediated through the GH-IGF-1 axis

Anti-Lipogenic Effects

In addition to promoting fat breakdown, AOD-9604 has been shown to inhibit lipogenesis (new fat formation):

• Reduced incorporation of fatty acids into triglycerides in adipocyte cultures
• Inhibited lipogenic enzyme activity
• The dual action (pro-lipolytic and anti-lipogenic) distinguishes it from agents that only stimulate fat burning

Cartilage and Joint Effects

More recent research has explored AOD-9604's effects on cartilage:

• Stimulation of proteoglycan and collagen synthesis in chondrocytes
• Potential chondroprotective effects in osteoarthritis models
• These findings are the basis for current clinical development in joint health applications

Research Summary

Pharmacokinetics

• Half-life: Estimated at approximately 30–60 minutes (limited published PK data)
• Route: Subcutaneous injection (clinical trials); oral formulations under investigation (GRAS application)
• IGF-1 effect: None — does not elevate circulating IGF-1
• Insulin effect: No adverse effects on insulin sensitivity documented in clinical trials
• Metabolism: Presumed proteolytic degradation; the disulfide bond provides moderate stability
• Oral bioavailability: Under investigation; the GRAS food ingredient pathway suggests potential for oral peptide delivery formulations, though bioavailability data has not been publicly disclosed in detail

Dosing Protocols

The following dosing information is compiled from published research and community discussion for educational purposes only. No FDA-approved human dosing guidelines exist for most research peptides. Always consult a qualified healthcare professional.

Reconstitution

Dosing Schedule

Syringe Measurements (U-100 insulin syringe)

Cycle Guidelines

• Cycle length: 8-12 weeks (up to 16 weeks)
• Route: Subcutaneous injection
• Timing: Morning, on an empty stomach
• Injection sites: Rotate between abdomen, thighs, and upper arms

Common Discussion Topics

1. Failed obesity trial — The Phase IIb trial failure is central to discussions about AOD-9604. Community opinions are divided on whether the compound is ineffective for weight loss or whether the trial design (dose selection, duration, patient population) was inadequate.

2. hGH fragment without hGH effects — The concept of isolating GH's fat-metabolizing properties from its growth and IGF-1 effects is appealing. Community discussion focuses on whether AOD-9604 truly delivers "GH-like fat loss" without GH side effects.

3. GRAS status — The 2020 GRAS determination is unusual for a peptide and has generated discussion about potential oral supplement formulations, though GRAS status as a food ingredient does not constitute approval for therapeutic claims.

4. WADA ban and AFL controversy — AOD-9604 was at the center of a high-profile doping scandal in Australian rules football in 2012-2013, leading to its addition to the WADA Prohibited List. This event significantly increased public awareness of the compound.

5. Cartilage repair potential — The shift from anti-obesity to joint health applications represents a pivot in the compound's development trajectory and generates interest in the regenerative medicine community.

6. Combination with GH secretagogues — Discussion around whether AOD-9604 can be meaningfully combined with CJC-1295/Ipamorelin stacks, or whether the fat-metabolizing effects overlap.

Related Compounds

• CJC-1295 — a GHRH analog that stimulates endogenous GH (which includes fat-metabolizing effects but also elevates IGF-1)
• Ipamorelin — a GH secretagogue; the GH released includes the same C-terminal region that AOD-9604 mimics
• HGH Fragment 176-191 — the unmodified fragment without the N-terminal tyrosine; sometimes conflated with AOD-9604 but lacks the tyrosine modification
• Tesamorelin — an FDA-approved GHRH analog specifically indicated for HIV-associated lipodystrophy (abdominal fat)
• 5-Amino-1MQ — a non-peptide compound discussed in fat metabolism contexts; acts through NNMT inhibition rather than GH pathways