AOD-9604 is a synthetic 16 amino-acid fragment derived from the C-terminal region of human growth hormone (residues 177-191). It was developed by Metabolic Pharmaceuticals in the 1990s based on the hypothesis that the lipolytic action of GH could be isolated from its other metabolic effects. The research record is informative — though the clinical translation has been limited.
Structure and origin
The native sequence (Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe) corresponds to residues 177-191 of human GH. AOD-9604 adds an N-terminal tyrosine for stability. The fragment is the region of GH research showed responsible for lipolytic action — separate from the residues mediating insulin-like growth factor signalling.
Mechanism hypothesis
The original research hypothesis was that AOD-9604 would:
- Stimulate lipolysis in adipose tissue
- Inhibit lipogenesis
- Avoid the insulin resistance, glucose intolerance, and IGF-1 elevation associated with full-length GH
In rodent and ex vivo human adipose tissue research, this hypothesis held — AOD-9604 stimulated fat oxidation without measurable effects on insulin signalling or IGF-1 levels.
Pre-clinical adipose tissue research
Heffernan et al. (2001) reported significant lipolytic activity in rat epididymal fat pads ex vivo. Ng et al. (2000) showed reduced body fat in obese mouse models without changes in glucose metabolism. The pre-clinical signal was consistent.
Clinical trial record — mixed results
The clinical translation was less clear. A phase 2 obesity trial (Stier et al., 2013) examined oral AOD-9604 in 502 adults with obesity over 24 weeks. Weight loss was modest:
| Arm | Mean weight loss |
|---|---|
| Placebo | ~1.0% |
| AOD-9604 1 mg | ~2.6% |
| AOD-9604 30 mg | ~2.6% |
The effect was statistically significant but small — not competitive with GLP-1 class molecules that emerged subsequently. Development was discontinued for obesity.
Cartilage and joint research
A secondary research line examined AOD-9604 for osteoarthritis and cartilage repair. The hypothesis was that GH fragment activity might extend to chondrocyte function. In vitro and animal data has been suggestive but clinical translation is limited.
Why GLP-1 agonists displaced AOD-9604 research
The modest clinical efficacy of AOD-9604 (~2.6% weight loss at 24 weeks) compared poorly to the GLP-1 class (15-25% loss over similar durations). Research investment shifted to incretin agonists. AOD-9604 remains a research-grade peptide for mechanism studies but is no longer a leading clinical candidate.
Pharmacokinetic profile
- Subcutaneous bioavailability: high
- Oral bioavailability: low (limits oral formulation viability)
- Plasma half-life: ~2 hours after subcutaneous
- Primarily renal clearance
Stability and reconstitution
AOD-9604 is supplied lyophilised. Reconstitution in bacteriostatic water at 1–2 mg/mL is standard. The disulfide-cysteine pair in the sequence is sensitive to reducing conditions — avoid reducing agents in reconstitution buffers.
Open research questions
- Why the ex vivo lipolytic signal did not translate to larger clinical weight loss
- Potential synergy with GLP-1 agonists in combination protocols
- Cartilage research signal validation
- Tissue-specific bioavailability optimisation
Chempeptides supplies HPLC-verified AOD-9604 with batch CoA — see the catalogue.
Research use only.