What it is
AOD-9604 is a 16-amino-acid synthetic peptide corresponding to the C-terminal region of human growth hormone (residues 176–191), with a tyrosine modification at the N-terminus to improve stability. It was developed by researchers at Monash University in Australia as part of an effort to isolate the lipolytic domain of hGH from its growth-promoting, insulin-desensitizing effects.[2]
The compound does not bind the GH receptor and does not stimulate IGF-1 production, distinguishing it from intact hGH and from GH secretagogues such as sermorelin or ipamorelin. AOD-9604 received Generally Recognized as Safe (GRAS) designation from the US FDA as a food ingredient in 2014, though it is not FDA-approved as a pharmaceutical drug. It is used in research settings and appears in some compounded preparations.
What researchers study it for
- Lipolysis and fat oxidation Heffernan et al. found that chronic AOD-9604 treatment significantly reduced body weight gain in obese mice, with increased in vivo fat oxidation and elevated plasma glycerol (a marker of lipolysis) compared to controls; importantly, AOD-9604 did not induce the hyperglycemia observed with intact hGH treatment at equivalent intervals.[2]
- Antilipogenic activity and adipose tissue metabolism Ng et al. demonstrated oral AOD-9604 reduced body weight gain in Zucker rats by more than 50% over 19 days, with increases in lipolytic activity and no adverse effect on insulin sensitivity; ex vivo analysis of human adipose tissue in a related study showed AOD-9604 increased lipolysis and decreased lipogenesis, suggesting the mechanism extends to human fat cells.[1]
- Beta-3 adrenergic receptor interaction Heffernan et al. used beta-3 adrenergic receptor (beta-3-AR) knock-out mice to investigate AOD-9604's mechanism; chronic treatment failed to produce weight loss or lipolytic changes in knock-out animals, implicating beta-3-AR expression upregulation as a contributor to the compound's sustained lipolytic effects.[3]
- Oral delivery and bioavailability Unlike most peptides, AOD-9604 and related hGH C-terminal fragments have been examined as orally active compounds; rodent studies demonstrated meaningful metabolic effects following oral administration, which was a primary driver of its early development as a potential anti-obesity pharmaceutical.[4]
- Cartilage repair and osteoarthritis Kwon and Park studied intra-articular AOD-9604 injections in a collagenase-induced rabbit knee osteoarthritis model, finding that AOD-9604 with hyaluronic acid produced significantly lower cartilage degeneration scores and shorter lameness periods than controls or hyaluronic acid alone, suggesting a potential cartilage-protective mechanism.[5]
Research context
AOD-9604's research history is unusual among peptides studied for fat metabolism. Its foundational science is solid: multiple independent studies from the Monash University group established consistent lipolytic and antilipogenic effects in rodent models, and ex vivo work in human adipose tissue added mechanistic plausibility for translational research.[1] The key distinguishing feature — that it acts independently of the GH receptor, avoiding the insulin resistance associated with intact hGH — was characterized early and held up across several animal studies.[2]
The compound progressed through Phase 2a and 2b clinical trials for obesity under the company Metabolic Pharmaceuticals, but the pivotal human obesity trials did not demonstrate sufficient weight loss to support regulatory approval, and pharmaceutical development was discontinued in the mid-2000s. The FDA GRAS designation it later received was as a food ingredient, not a drug approval. Research interest has since shifted partly toward joint health applications; the cartilage repair angle is supported by preclinical work, though no human clinical trials in osteoarthritis have been published as of this writing.[5] Most available evidence remains preclinical, and the gap between animal model results and human outcomes should be factored into any evaluation of the literature.
Typical research parameters
| Parameter | Detail |
|---|---|
| Common vial sizes | 2 mg, 5 mg (some vendors offer 500 mcg vials) |
| Supplied as | Lyophilized powder; reconstituted with bacteriostatic water |
| Storage | Refrigerate; lyophilized powder stable at room temperature short-term; protect from light |
| Stability | Lyophilized: 24+ months under appropriate conditions; reconstituted: approximately 28 days refrigerated |
| Administration studied | Subcutaneous injection (primary research use); oral administration was examined in animal studies and early clinical development; intra-articular injection studied in osteoarthritis models |
References
- [1] Ng FM, Sun J, et al. Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Horm Res. 2000;53(6):274-8. PubMed ↗
- [2] Heffernan MA, Thorburn AW, et al. Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment. Int J Obes Relat Metab Disord. 2001;25(10):1442-9. PubMed ↗
- [3] Heffernan M, Summers RJ, et al. 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;142(12):5182-9. PubMed ↗
- [4] Heffernan MA, Jiang WJ, et al. Effects of oral administration of a synthetic fragment of human growth hormone on lipid metabolism. Am J Physiol Endocrinol Metab. 2000;279(3):E501-7. PubMed ↗
- [5] Kwon DR, Park GY. Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model. Ann Clin Lab Sci. 2015;45(4):426-32. PubMed ↗