AOD-9604 – Research Peptide

What AOD-9604 is

AOD-9604 — “Anti-Obesity Drug 9604” — is a synthetic peptide corresponding to the C-terminal fragment of human growth hormone, residues 177–191, with an additional tyrosine added at the N-terminus. It carries an internal disulfide bond and is commonly written as hGH fragment 176-191^[1].

The design idea was elegant: isolate the region of growth hormone associated with fat metabolism, discard the rest, and get the metabolic activity without the diabetogenic and growth-promoting effects of the whole molecule. Metabolic Pharmaceuticals took it into human trials for obesity.

It did not work. That sentence is the most important one on this page and it is the one every other listing for this compound omits.

Structure and identity

AOD-9604 · C78H123N23O23S2 · 1815.1 g/mol · Source: PubChem CID 71300630

Sixteen residues; two cysteines forming the disulfide that accounts for both sulfur atoms in the formula. The anti-doping literature describes it precisely as “a peptide consisting of the C-terminal fragment of human growth hormone from amino acids 177–191 with an additional tyrosine residue at the N-terminus”^[1].

One practical stability note from the analytical literature, which matters for handling: in a 2026 validation study, AOD9604 and hGH 176-191 were among the compounds extensively degraded after one week in serum and plasma at 4 °C and 22 °C, while remaining stable for at least two months at −20 °C^[2]. This is not a robust peptide in solution at room temperature.

Where the evidence stands

This is the section most vendors skip. It is the most important one on the page.

The obesity programme that failed human

AOD-9604 entered Phase 2a trials for obesity by February 2002^[3]. Through the mid-2000s it appears repeatedly in reviews of the obesity pipeline — listed alongside rimonabant, cetilistat and lorcaserin as a “human growth hormone fragment” in clinical development for weight loss^[4][5].

Then it disappears from those reviews. It never reached Phase 3. It was never approved by any regulator anywhere for any indication. Metabolic Pharmaceuticals discontinued it as an obesity drug candidate.

A 2026 narrative review in Frontiers in Endocrinology, stratifying performance-enhancing peptides by evidence tier, places AOD9604 (hGH 176-191) among the GH-axis compounds lacking regulatory approval for physique or performance indications, with uncertainty around composition, dose and stacking in unregulated supply^[6]. A 2026 review in Sports Medicine classifies it explicitly as one of the unapproved peptides in a parallel “gray market” operating outside regulatory oversight — favourable animal data, scarce human safety data, potential for serious harm^[7].

A gap in the primary literature

Animal models animal

In a collagenase-induced knee osteoarthritis model in 32 New Zealand white rabbits, weekly ultrasound-guided intra-articular injections of 0.25 mg AOD9604, alone or with hyaluronic acid, were compared against saline and against hyaluronic acid alone. Gross morphological and histopathological scores were significantly lower (less cartilage degeneration) in all three treatment groups than in saline controls, and lowest in the combined AOD9604 + hyaluronic acid group; the lameness period was shortest in that group^[8].

That is a rabbit joint injection study with n=8 per group. It is not an obesity result, it is not a human result, and it is the strongest positive animal finding in the recent AOD-9604 literature. The distance between “cartilage scores in collagenase-injected rabbit knees” and anything a person would experience is very large, and we are not going to pretend otherwise.

What it does not do to GH signalling

One genuinely useful and well-verified finding: AOD-9604 does not interfere with the WADA hGH isoform immunoassay^[9]. That is a technical result about anti-doping test performance. It is often mis-sold as evidence that AOD-9604 “doesn’t affect growth hormone” or “doesn’t raise IGF-1.” It is not that. It is a statement about whether a particular antibody-based test cross-reacts with the fragment. Do not read it as a pharmacological or safety claim.

Detection and doping controls

AOD9604 is a routine anti-doping target. A validated solid-phase-extraction method detects it in urine down to 50 pg/mL. Six potential metabolites were identified after incubation in serum and urine; one — the fragment CRSVEGSCG — is substantially more stable than the parent compound and may extend the detection window^[1]. AOD9604 has been identified by Belgian authorities in seized pharmaceutical preparations^[10] and is included in multi-analyte screens covering prohibited peptides under 2 kDa^[11].

Limitations of the literature

The pivotal human data are not in the public scientific record. The most important experiment ever done with this compound — does it cause weight loss in obese humans — has no peer-reviewed publication that we can find. Whatever it showed, it was not enough to continue.

The mechanism story outran the clinical result. “The lipolytic domain of growth hormone” is a compelling sentence. It is a hypothesis about a fragment. The fragment was tested and the drug was abandoned.

Human safety data are thin. There is no published long-term human safety dataset. The 2026 reviews describe the human safety evidence for this class as scarce^[6][7].

Regulatory and anti-doping status

AOD-9604 is named by name on the WADA Prohibited List under S2.2.3, Growth Hormone (GH), its analogues and fragments — the clause reads “growth hormone fragments, e.g. AOD-9604 and hGH 176-191”^[12]. Section S2 substances are prohibited at all times, in and out of competition. There is no ambiguity here and no annual drift to hope for: it is on the list by name.

AOD-9604 has not been approved as a drug for any indication by the FDA or any other regulatory authority. Anti-doping lists change annually and by governing body. If you compete under any tested organisation, the only reliable source is that organisation’s current prohibited list — not this page, and not any vendor’s.

What we don’t know

• What the human obesity trials actually measured. The results were never published in the indexed literature.
• Whether the rabbit intra-articular cartilage finding means anything in any other species. No follow-up work exists.
• What repeated subcutaneous exposure does in a human over months. No study.
• Long-term safety in humans is uncharacterised. Per-kilogram dosing in animal models does not scale to humans, and nothing on this page should be read as implying that it does.

We supply this compound for laboratory research. The design rationale is interesting and the anti-doping chemistry is well characterised. The clinical file is a discontinued obesity programme with no published result. We are not going to pretend it is more than it is.