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AOD-9604

AOD-9604 is a synthetic 16-amino acid peptide fragment derived from the C-terminal domain of human growth hormone (amino acids 176-191) with a stabilizing tyrosine substitution at the N-terminus. Originally developed by Metabolic Pharmaceuticals Ltd. in Australia during the 1990s as an "Anti-Obesity Drug," it was designed to harness growth hormone's lipolytic properties while avoiding broader metabolic and growth-promoting effects.

Despite completing six human clinical trials involving over 900 participants, AOD-9604 failed to achieve statistical significance in its largest Phase IIb trial and development was terminated in 2007. The peptide lacks regulatory approval from any major health authority worldwide. Its selective mechanism targeting adipose tissue without affecting IGF-1 pathways or glucose homeostasis distinguishes it from full-length growth hormone therapy, offering unique research applications in metabolic studies and potential cartilage repair applications.

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Overview

AOD-9604 exhibits rapid degradation in biological systems through amino-terminal truncation, with sequential amino acid removal being the primary metabolic pathway. The peptide maintains structural similarities to the homologous region of naturally occurring human growth hormone while demonstrating improved stability through its synthetic modifications. Detection in plasma and urine is possible using specialized LC/MS/MS assay methods for up to several days post-administration.

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Chemical structure & Properties

  • Molecular Formula: C₇₈H₁₂₃N₂₃O₂₃S₂
  • Molecular Weight: 1815.1 Daltons
  • Sequence: Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe
  • Disulfide Bridge: Cys7-Cys14 (cyclic structure)
  • CAS Number: 221231-10-3
  • Half-life: Approximately 4 minutes in plasma (rapid degradation)
  • Stability: Enhanced compared to native hGH C-terminus through N-terminal tyrosine modification

Mechanism of Action

AOD-9604 exerts its biological effects through multiple interconnected molecular mechanisms:

BETA-3 ADRENERGIC RECEPTOR INVOLVEMENT

Beta-3 adrenergic signaling has been proposed as one mechanism of AOD-9604 activity:

  • Lipolysis: May promote breakdown of stored fat.
  • Lipogenesis: May reduce fat-storage pathways.
  • Evidence: Support for beta-3 adrenergic involvement comes mainly from animal and preclinical data.
  • Human relevance: Beta-3 adrenergic signalling has not been established as the mechanism of AOD-9604's effects in humans.

Lipolytic and Anti-Lipogenic Effects

AOD-9604 influences fat metabolism by:

  • Promoting the breakdown of stored triglycerides into free fatty acids and glycerol
  • Stimulating lipolysis preferentially in obese fat cells over lean adipocytes
  • Inhibiting lipogenesis (conversion of non-fat substrates into fatty acids)
  • Enhancing fat oxidation and energy expenditure

Selective Metabolic Targeting

The peptide demonstrates targeted effects through:

  • Absence of IGF-1 elevation, avoiding growth hormone-mediated anabolic effects
  • No significant impact on insulin sensitivity or glucose tolerance
  • Preservation of natural hormonal feedback mechanisms
  • Tissue-specific action limited primarily to adipose tissue

Alternative Metabolic Pathways

Research indicates additional mechanisms including:

  • Potential induction of apoptosis in white adipocytes
  • Enhanced energy expenditure independent of beta-3-AR activation
  • Direct cellular metabolic effects not mediated through traditional growth hormone pathways
  • Possible cartilage regenerative properties through undefined mechanisms

Areas Investigated in

the Research Literature

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Current Clinical Evidence

Published Human Studies

Phase I and II Clinical Trials (2001-2007):

  • Study Population: Over 900 participants across six randomized, double-blind, placebo-controlled trials
  • Dosing Regimens: Various doses including 0.25 mg, 0.5 mg, and 1.0 mg daily
  • Administration Routes: Both intravenous and oral formulations tested
  • Primary Outcomes: Safety, tolerability, and weight reduction assessment

Phase IIb Efficacy Study (12-week trial):

  • Study Population: 300 obese adults
  • Intervention: AOD-9604 1 mg daily
  • Results: Average weight loss of 2.6 kg vs 0.8 kg in placebo group
  • Significance: Modest but statistically significant weight reduction

Phase IIb Pivotal Trial (24-week study):

  • Study Population: 534 obese participants (BMI 30-45 kg/m²)
  • Intervention: Daily doses of 0.25 mg, 0.5 mg, or 1.0 mg
  • Results: No statistically significant weight loss compared to placebo
  • Outcome: Development termination due to insufficient efficacy

Long-term Safety Analysis:

  • Study Design: Comprehensive safety evaluation across all clinical trials
  • Primary Focus: IGF-1 levels, glucose tolerance, and immunogenicity
  • Results: Excellent safety profile with no significant adverse events
  • Key Findings: No antibody formation, no glucose metabolism disruption

Research Limitations

Current clinical evidence is constrained by:

  • Limited Efficacy Data: Conflicting results between early and late-stage trials
  • Development Termination: Insufficient commercial viability led to discontinued research
  • Narrow Study Focus: Primary concentration on obesity with limited investigation of other applications
  • Short-term Data: Lack of long-term safety and efficacy information
  • Population Specificity: Studies conducted primarily in obese populations

Safety Profile and Considerations

Clinical Safety Data

Extensive human clinical trials demonstrate:

  • Excellent Tolerability: Adverse-event rates were broadly comparable to placebo in the reported trials, which were short-term
  • No Serious Adverse Events: No withdrawals or serious complications related to AOD-9604
  • Minimal Side Effects: Occasional injection site reactions, mild fatigue, or headache
  • No Immunogenicity: Absence of antibody formation against the peptide

Metabolic Safety

AOD-9604 demonstrates favorable metabolic effects:

  • No IGF-1 Elevation: Avoids growth hormone-mediated complications
  • Glucose Homeostasis Preservation: No negative impact on insulin sensitivity or glucose tolerance
  • Cardiovascular Safety: No adverse effects on blood pressure or cardiac function
  • Endocrine Stability: Minimal disruption of natural hormonal systems

Theoretical Concerns

Potential considerations include:

  • Limited Long-term Data: Insufficient information on extended use effects
  • Individual Variability: Variable responses observed in clinical populations
  • Drug Interactions: Potential interactions with metabolic medications require monitoring
  • Population-Specific Effects: Different responses may occur in various demographic groups

Contraindications

AOD-9604 should be avoided in:

  • Active Malignancy: Theoretical concerns about growth promotion in cancer
  • Pregnancy and Lactation: Insufficient safety data for reproductive use
  • Severe Metabolic Disorders: Caution in uncontrolled diabetes or metabolic dysfunction
  • Known Peptide Hypersensitivity: Allergic reactions to synthetic peptides

Regulatory Status and Legal Considerations

Regulatory information current as of 28 August 2026. This is a summary, not legal or medical advice, and status can change.

FDA Status

No Approved Medical Use:

  • FDA Status: AOD-9604 is not on the FDA's active Category 2 list. It appears in the nominated-but-withdrawn section of the FDA's bulk drug substances page, meaning the nomination was withdrawn rather than acted on. On Dec. 4, 2024, the Pharmacy Compounding Advisory Committee voted against recommending AOD-9604 for the 503A bulk drug substances list. It is not on that list, so no lawful compounding pathway currently exists, and AOD-9604 remains an unapproved investigational compound in the United States.
  • International Status: No regulatory approval from any major health authority worldwide
  • Development Status: Classified as investigational compound under pre-clinical/clinical development

WADA Status

Prohibited Substance Classification:

  • Category: S2.2.3 growth hormone fragments, e.g. AOD-9604/hGH 176-191; prohibited at all times.
  • Rationale: No current approval for human therapeutic use
  • Athletic Use: Banned in all competitive sports
  • Detection: Urine testing available for anti-doping purposes

Legal Availability

Research Chemical Status:

  • Commercial Availability: Available through research chemical suppliers
  • Quality Control: Variable standards depending on supplier
  • Regulatory Oversight: Subject to research chemical regulations
  • Medical Use: Not approved for clinical therapeutic applications

Regional Variations:

  • United States: Research use only, not FDA-approved
  • Australia: Schedule 4 prescription-only medicine classification
  • European Union: No medical approval, research use restrictions apply
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Conclusion

What the evidence supports

AOD-9604 is a synthetic fragment of human growth hormone that has been studied in humans for fat metabolism, with a safety database of more than 900 participants across six controlled trials, and more recently in preclinical work on cartilage repair. Those obesity trials did not demonstrate consistent efficacy, and development was terminated in 2007; there is no established therapeutic use and no long-term outcome data for the applications discussed here. AOD-9604 is not FDA approved and remains an unapproved investigational compound; in December 2024 the Pharmacy Compounding Advisory Committee voted against adding it to the 503A bulk drug substances list. This page summarizes the published research and nothing further.

AOD-9604 SCIENTIFIC

DATA SUMMARY

MOLECULAR CHARACTERISTICS
PRECLINICAL EFFICACY DATA
CLINICAL EVIDENCE SUMMARY
SAFETY PROFILE
REGULATORY STATUS
Parameter
Molecular Weight
Amino Acid Length
Half-Life
Bioavailability
Detection Window
Value
1815.1 Da
16 residues
~4 minutes (plasma)
Active both oral and injectable
Up to several days (urine)
Application
Fat Loss
Beta-3 Receptor Activity
Cartilage Repair
Metabolic Effects
Reported outcome (model)
Reduced weight gain (obese rats), enhanced lipolysis
Enhanced beta-3-AR expression, lipolytic sensitivity
Improved cartilage structure, reduced joint dysfunction
No IGF-1 elevation, preserved glucose tolerance
Study Type
Phase I/II Trials
12-Week Efficacy Study
24-Week Pivotal Trial
Population
900+ participants (6 studies)
300 obese adults
534 obese participants
Results
Excellent safety profile, no serious adverse events
2.6 kg vs 0.8 kg weight loss (vs placebo)
No statistically significant weight loss
Limitations
Mixed efficacy results
Modest effect size
Long-term data needed
Parameter
Acute Toxicity
IGF-1 Effects
Glucose Metabolism
Immunogenicity
Long-term Safety
Finding
No acute toxicity observed in animal studies
No elevation of IGF-1 levels in humans
No impairment of glucose tolerance or insulin sensitivity
No antibody formation detected
No long-term safety data; all trials were short-term
Authority
FDA
WADA
Australia TGA
EU/UK
Classification
Investigational Compound
S2.2.3 Growth Hormone Fragments
Schedule 4 Medicine
Unscheduled
Status
Not approved for human use
Prohibited in sports
Prescription-only
Research use only

About this library

This library is published for education. It summarizes published research on compounds studied in this field. Many have no approved medical use, and several cannot lawfully be compounded in the United States. The presence of a page here does not mean Paragon offers that compound. Nothing on these pages is an offer to treat.

This page is general education about a compound studied in this field. Nothing here is medical advice, a recommendation, or an offer to prescribe or supply. A page appearing in this library does not mean Paragon Sports Medicine offers that compound.

Disclaimer: This information is provided for educational purposes only and does not constitute medical advice. AOD-9604 is not approved by the FDA or any major regulatory authority for therapeutic use. The peptide is classified as a research chemical and prohibited for use in competitive athletics by WADA.

Patients and researchers should consult with qualified healthcare providers and ensure compliance with applicable regulations before considering any use of AOD-9604. Regulatory status as of April 22–23, 2026

Statements on this page have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Many peptides described here are not FDA approved for the uses discussed, and some cannot lawfully be compounded in the United States. Nothing on this page is medical advice or a recommendation for any individual. Whether any therapy is appropriate depends on your history, your laboratory results, and a clinical evaluation. Individual results vary. This page is published for education. Use of this site does not create a physician-patient relationship.

References

01
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. Endocrinology. 2001.
02
AOD-9604 Metabolic. Curr Opin Investig Drugs. 2004.
03
Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model. Ann Clin Lab Sci. 2015.
04
Detection and in vitro metabolism of AOD9604. Drug Test Anal. 2015.