AOD-9604: Research Profile

Palmetto Peptides Research Team

February 22, 2026

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AOD-9604 (Anti-Obesity Drug 9604) is a synthetic peptide fragment corresponding to the C-terminal region of human growth hormone (hGH), specifically amino acids 176–191. Unlike full-length growth hormone, AOD-9604 does not bind the GH receptor in a manner that activates systemic anabolic or diabetogenic effects — instead, its biological activity is focused on lipolytic (fat-burning) mechanisms, making it a highly specific research tool for studying adipose tissue metabolism without the insulin-antagonizing effects associated with full GH administration.

Background: GH and Fat Metabolism

Growth hormone has long been known to stimulate lipolysis — the breakdown of stored triglycerides in adipocytes into free fatty acids and glycerol, which are released into circulation as fuel. However, supraphysiological GH also causes insulin resistance and other metabolic side effects that limit its research utility as a pure lipolytic agent. The identification of the C-terminal fragment responsible for GH's lipolytic effects — without the anabolic and diabetogenic properties — led to the development of AOD-9604 as a selective lipolytic research compound.

Structure and Mechanism

AOD-9604 is a 16-amino acid peptide (Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe) with a disulfide bond between the two cysteine residues, mirroring the structural feature present at this region of the native GH molecule. This disulfide-stabilized structure is important for maintaining the correct conformation required for biological activity.

Lipolytic Mechanisms

Research has proposed that AOD-9604 exerts its lipolytic effects through mechanisms that differ from full-length GH's receptor-mediated signaling:

Stimulation of beta-3 adrenergic receptor activity in adipocytes, promoting cAMP-mediated activation of hormone-sensitive lipase (HSL)
Inhibition of lipogenesis (de novo fat synthesis) in fat cells — reducing lipid accumulation without requiring GH receptor binding
Possible direct effects on fat cell metabolism through mechanisms not fully characterized, as the compound's specific receptor has not been definitively identified

Importantly, AOD-9604 does not bind IGF-1 receptors and does not stimulate IGF-1 production, distinguishing its metabolic profile from full-length GH at research-relevant doses.

Key Research Findings

Preclinical Obesity Models

Research in diet-induced obese mouse models demonstrated that AOD-9604 reduced body weight and fat mass through enhanced fat oxidation without affecting lean mass or causing the insulin resistance associated with exogenous GH. Studies published by Heffernan et al. at Monash University established that AOD-9604 administered intraperitoneally produced significant reductions in adiposity in obese rodents, with effects comparable to full-length GH but without the diabetogenic side effects.

Clinical Research

AOD-9604 progressed through Phase I-III clinical trials for obesity under development by Metabolic Pharmaceuticals. Phase II data showed modest weight loss effects in human subjects, though Phase III results were insufficient for regulatory approval. Notably, clinical safety data established a favorable tolerability profile — no significant effects on blood glucose, insulin sensitivity, IGF-1 levels, or cardiovascular parameters were observed at studied doses. This safety profile has sustained research interest in the compound as a lipolytic research tool.

Cartilage and Bone Research

An unexpected research finding was AOD-9604's apparent effects on cartilage and bone metabolism. Studies suggested anti-inflammatory and potentially chondroprotective effects in osteoarthritis models, leading to research into the compound's utility beyond metabolic applications. While the mechanism for these effects is less established than its lipolytic activity, this research avenue has generated interest in AOD-9604 as a multi-application research compound, particularly alongside BPC-157 in joint and connective tissue models.

AOD-9604 vs. Full-Length Growth Hormone

Receptor binding: AOD-9604 does not activate GH receptor signaling; full-length GH does
IGF-1: AOD-9604 does not elevate IGF-1; full GH does substantially
Insulin resistance: AOD-9604 does not cause insulin resistance; full GH does at supraphysiological doses
Anabolic effects: AOD-9604 lacks the anabolic protein synthesis effects of GH
Lipolysis selectivity: AOD-9604 selectively targets fat metabolism; full GH affects multiple tissues

Research Protocols

AOD-9604 is reconstituted from lyophilized powder in bacteriostatic water prior to use. Research protocols in animal models have typically used daily subcutaneous administration, with body composition assessment via DEXA or MRI as primary endpoints. Researchers studying AOD-9604 alongside metabolic peptides like Semaglutide or Tirzepatide should note the distinct mechanisms — AOD targets adipocyte lipolysis directly, while GLP-1/GIP receptor agonists primarily reduce food intake.

Frequently Asked Questions

Why was AOD-9604 developed from hGH amino acids 176–191 specifically?

Systematic studies of hGH fragment activity mapped the lipolytic domain to the C-terminal region. The 176–191 fragment with its disulfide bond retained meaningful lipolytic activity while losing the N-terminal sequences required for GH receptor binding and IGF-1 stimulation — creating a naturally delineated pharmacological profile.

Is AOD-9604 the same as the hGH fragment?

AOD-9604 is sometimes referred to as "hGH fragment 176–191" — they are the same compound. The "AOD-9604" designation originated from Metabolic Pharmaceuticals' development program. Researchers may encounter both names in the literature.

How does AOD-9604 relate to GH-releasing peptide research?

Compounds like Ipamorelin and Sermorelin stimulate endogenous GH secretion from the pituitary. AOD-9604 bypasses the pituitary entirely and acts directly on adipose tissue. These represent mechanistically distinct approaches to studying GH-related fat metabolism in research settings.

References

Heffernan M, et al. (2001). The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knockout mice. Endocrinology. PMID: 11356686
Ng FM, et al. (2000). Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone. Hormone Research. PMID: 10895041
Stanley TL, Grinspoon SK. (2015). Effects of growth hormone-releasing hormone on visceral fat, metabolic, and cardiovascular indices in human studies. Growth Hormone & IGF Research. PMID: 25656379

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