AOD9604: Six Human Trials, One Discontinued Program, One Honest Spec Sheet

What is AOD9604?

AOD9604 is a 16-amino-acid synthetic peptide corresponding to the C-terminal region of human growth hormone (residues 177–191), with an N-terminal tyrosine substituted for the native phenylalanine. Molecular formula: C78H123N23O23S2. Molecular weight: 1815.1 Da. CAS number: 221231-10-3. Also known as HGH Fragment 176-191, Tyr-hGH177–191, and hexadecapeptide AOD9604.

The compound was developed by Metabolic Pharmaceuticals (Australia) as an anti-obesity investigational drug. Its defining pharmacological characteristic: it does not bind the growth hormone receptor and does not trigger IGF-1 production. That selective mechanism is the compound's core research premise — lipolysis without the hormonal cascade that makes full-length hGH problematic in metabolic contexts ^[1][2].

AOD9604 is not FDA-approved for any indication. It is not a controlled substance under DEA scheduling. Its 503A compounding pharmacy status was under FDA Pharmacy Compounding Advisory Committee review as of December 2024; the nominator had withdrawn the nomination in September 2024. The development program was terminated in 2007 after the Phase IIb trial did not meet its primary weight-loss endpoint ^[4].

AOD9604 Peptide: Structure and Research Context

The AOD9604 peptide occupies a specific niche in the research literature: a fragment study. The hypothesis was that the lipolytic activity of full-length hGH resides in its C-terminal domain, and that isolating that domain — re-engineered with a tyrosine at the N-terminus for stability — would produce selective fat-metabolism effects without the receptor-level side effects of the parent hormone.

Preclinical data in obese mice and Zucker fatty rats supported the hypothesis. In obese ob/ob mice treated for 14 days via continuous infusion, AOD9604 reduced body weight gain and increased fat oxidation without inducing hyperglycemia or suppressing insulin secretion — a result that full-length hGH could not match ^[1]. In Zucker fatty rats, the compound stimulated hormone-sensitive lipase (HSL), inhibited acetyl-CoA carboxylase (ACC), and reduced adipocyte diameter from approximately 110 to 80 micrometers over 20 days ^[3].

The beta-3 adrenergic receptor (beta3-AR) data cemented the mechanism: both AOD9604 and full-length hGH normalized beta3-AR mRNA expression in obese mice; when administered to beta3-AR knockout mice, the chronic weight-loss effect of both compounds was absent — directly demonstrating the receptor pathway's requirement ^[2]. Six randomized double-blind placebo-controlled human trials followed. The mechanism of action: how AOD9604 stimulates lipolysis and AOD9604 dosage protocols studied in clinical research are covered in full on their respective pages.

AOD9604 Research Benefits: Lipolysis, Joint Health, and Metabolic Safety

Three research benefit areas emerge from the published literature:

1. Selective lipolysis. AOD9604 stimulates fat breakdown via the beta3-AR/cAMP/HSL pathway without GH receptor activation. In preclinical models, this produced dose-dependent fat reduction and elevated plasma glycerol (index of lipolysis), without hyperglycemia or lean-mass loss ^[1][3]. The clinical data was weaker — the Phase IIb trial did not show statistically significant weight loss versus placebo — but the preclinical mechanism signal is well-documented.

2. Metabolic safety profile. No IGF-1 elevation was detected at any dose across all six human trials ^[5]. Oral glucose tolerance testing showed no adverse glucose effects across the program; a trend toward benefit was observed in subjects with impaired glucose tolerance at the 1 mg oral dose ^[6][21]. Zero participants across approximately 900 subjects developed anti-AOD9604 antibodies over up to 24 weeks of treatment ^[13].

3. Cartilage and joint health research. A secondary research direction emerged after the obesity program ended. Intra-articular injection of AOD9604 in a rabbit osteoarthritis model reduced lameness recovery time; combined AOD9604 plus hyaluronic acid produced the largest cartilage morphology and histopathology improvements ^[11]. In vitro bovine chondrocyte studies showed upregulation of proteoglycans and collagen — key extracellular matrix components ^[12]. No human osteoarthritis trials have been published.

AOD9604 Regulatory and Legal Status

AOD9604 is not FDA-approved for any indication. The development program was discontinued in 2007 after the Phase IIb OPTIONS study (METAOD006) did not demonstrate statistically significant weight loss versus placebo at 24 weeks. The compound is not a DEA-controlled substance. Its 503A compounding pharmacy eligibility was under FDA PCAC review as of December 2024 [RS1].

For athletes: AOD9604 is classified under WADA 2026 Prohibited List Section S2.2.3 — Growth Hormone, its analogues and fragments. It is prohibited at all times in competitive sport. Validated detection methods exist, with a stable CRSVEGSCG metabolite fragment extending urinary detection windows ^[14]. This site is an editorial digest of the published research record. See AOD9604 regulatory and legal status for the full regulatory Q&A.

Is AOD9604 a Steroid or Hormone?

No. AOD9604 is a 16-amino-acid peptide, not a steroid. It does not share the four-ring steroidal backbone and does not activate androgen, estrogen, or glucocorticoid receptors. It is structurally derived from human growth hormone but activates distinct cellular pathways at the adipocyte level — specifically the beta3-adrenergic receptor cascade — independently of the GH receptor ^[1][2]. It is also not full-length hGH. The AOD9604 vs HGH fragment 176-191 section on the research page covers the naming overlap in detail.