Encyclopedia entry
AOD-9604
Oliver Mackman · Editorial director · Best Business Loans Ltd (16833937)
Last updated 2026-06-04
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AI-friendly summary · AOD-9604
AOD-9604 is a synthetic 16-amino-acid peptide corresponding to residues 177 to 191 of human growth hormone, developed by Metabolic Pharmaceuticals (Melbourne) during the late 1990s and 2000s. The obesity development programme reached Phase IIb and Phase III before being discontinued because the human trials did not replicate the lipolytic signal seen in rodent models. No marketing authorisation has been granted in any jurisdiction.
Mechanism of action
How AOD-9604 works
AOD-9604 corresponds to the C-terminal fragment of human growth hormone. The originating hypothesis from Metabolic Pharmaceuticals was that lipolytic activity of full-length hGH resided in this fragment, while the IGF-1-mediated anabolic effects required the intact molecule. In rodent adipocyte models the fragment was reported to stimulate lipolysis without activating the growth hormone receptor in the canonical way. The precise receptor target in humans is not established and the proposed mechanism has not been confirmed in human pharmacology.
Source: Heffernan M et al. Endocrinology, 2001 (originating Metabolic Pharmaceuticals series)
What the literature shows
AOD-9604 has one of the more unusual evidence profiles in this encyclopedia. Roughly 30 to 40 peer-reviewed papers exist, the preclinical work was supportive of lipolytic activity in rodent adipocytes, and the compound progressed through full Phase I, Phase II, and Phase III human development before the programme was discontinued. The Phase III obesity trial did not produce sufficient efficacy to support a regulatory submission.
- · Developed by Metabolic Pharmaceuticals (Melbourne, Australia) in the late 1990s and early 2000s.
- · Rodent adipocyte studies reported lipolytic effects supporting the C-terminal-fragment hypothesis.
- · Phase I and Phase II trials in overweight human subjects tested oral and intranasal formulations.
- · Phase IIb and Phase III trials did not replicate sufficient efficacy for regulatory submission.
- · Programme discontinued. No FDA, EMA, or TGA filing was made.
- · "HGH fragment 176-191" is a retailer alias. The 176-191 versus 177-191 numbering discrepancy reflects different conventions for the signal-peptide-cleaved mature hGH sequence.
Evidence quality assessment: the preclinical literature for lipolytic activity exists and was sufficient to support Phase I and Phase II development. The human RCT programme did not confirm the animal findings at the level required for regulatory approval. Claims circulating in online communities that draw only on the preclinical data or the early Phase II signal should be read in this context.
UK regulatory status
AOD-9604 sits outside the Misuse of Drugs Act 1971 and outside the Psychoactive Substances Act 2016. It has zero UK marketing authorisations and zero approved indications in any jurisdiction globally. UK retailers can sell it lawfully only by labelling it for "research use only, not for human or animal consumption" and by avoiding any therapeutic claim.
- · Not a controlled drug under the Misuse of Drugs Act 1971.
- · Not scheduled under the Psychoactive Substances Act 2016.
- · No MHRA marketing authorisation as a medicine in the UK.
- · Not approved in any jurisdiction globally, including the US (FDA), EU (EMA), or Australia (TGA).
- · Sold legally as a research chemical by UK retailers when marketed without therapeutic claims.
- · Becomes an unlicensed medicinal product the moment a retailer or commentator makes therapeutic claims about it.
- · The failed Phase III programme is relevant context: the compound was tested at scale in humans and did not meet the regulatory bar for an approved medicine.
Risks and unknowns
What the literature does not yet show about AOD-9604
Known concerns
- Phase III obesity programme failed to meet efficacy endpoints. The compound was tested at scale and not submitted for approval.
- No long-term safety data exists outside the Metabolic Pharmaceuticals trial programme, which has been inactive for over a decade.
- Purity of UK research-peptide supply varies between retailers. CoA gating and HPLC analysis differ.
- Cold-chain handling between manufacture and delivery is not standardised across the research-peptide market.
Open questions in the literature
- The precise receptor target of AOD-9604 in humans has never been definitively established.
- Why the rodent lipolytic signal did not translate to humans at Phase III is not fully resolved in the published literature.
- Long-term effects beyond the duration of the Metabolic Pharmaceuticals trial programme are not characterised.
- Pharmacokinetics of oral and intranasal formulations versus injectable preparations have produced inconsistent results across the literature.
Regulatory note
Not a controlled drug under the Misuse of Drugs Act 1971. Not scheduled under the Psychoactive Substances Act 2016. No UK marketing authorisation as a medicine. Not approved in any jurisdiction globally. Becomes an unlicensed medicinal product the moment a retailer or commentator makes therapeutic claims about it.
Important: PeptideClear publishes encyclopedia commentary only and does not recommend human use. Speak to a UK-registered prescriber before any medical decision.
Where to learn more
- · PubMed search: AOD-9604 returns the Metabolic Pharmaceuticals preclinical series and published Phase II data.
- · PubMed search: HGH fragment 176-191 covers the alternative naming convention.
- · ClinicalTrials.gov: AOD9604 for registered Phase IIb and Phase III obesity trials.
- · UK retailer purity comparison: research peptides UK retailers.
Frequently asked questions
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Where to buy AOD-9604 in the UK
Compare UK research-peptide retailers stocking AOD-9604, with current prices and CoA status. Research use only, not for human or animal consumption.
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Read the clinical evidence record for AOD-9604
Top peer-reviewed citations, mechanism of action, structured UK regulatory status. Machine-readable companion to this encyclopedia entry.
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