AOD-9604: A Growth Hormone C-Terminal Fragment With Human Trial Data but No Clear Path Forward

This content is provided by Superpower Health for educational and informational purposes only. AOD-9604 is currently unavailable through Superpower due to FDA Category 2 classification. AOD-9604 is not FDA-approved for any indication. This page is not a substitute for medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.

A compound can have a credible molecular rationale, a decade of preclinical work, and a completed Phase 2b human trial — and still not be available by prescription. AOD-9604 is in that position. The evidence base that once supported it as a promising fat-loss compound has not disappeared. The regulatory pathway that made it accessible through compounding pharmacies has closed.

Here is what AOD-9604 is, what the research actually showed, why the pivotal human trial mattered, and where the compound stands today.

Key Takeaways

• Regulatory Status: FDA Category 2 bulk drug substance as of April 2026; compounding restricted pending further FDA review. No FDA-approved indication exists. Australian TGA rejected an obesity indication following the Phase 2b failure.
• Research Stage: Completed Phase 2b human obesity trial (failed to meet primary endpoint); GRAS status granted for dietary supplement use; preclinical cartilage data only for joint/OA indications
• Availability: Currently unavailable through most compounding pharmacies due to FDA Category 2 classification; gray-market injectable products continue to circulate but are unregulated
• Prescribing information: No FDA drug label exists. See PubChem CID 10270282 for compound reference data.
• How it works: Synthetic C-terminal fragment of human growth hormone (amino acids 177-191, plus an N-terminal tyrosine) studied for lipolytic and antilipogenic activity in fat tissue
• What the research shows: Preclinical data demonstrated lipid-metabolism activity; the single adequately powered human obesity trial did not replicate those effects versus placebo

Where AOD-9604 Comes From and How It Works

Origin and discovery

AOD-9604 traces its origins to foundational work at Monash University in the early 1990s, where researcher Frank M. Ng and colleagues investigated whether the lipolytic activity of full-length human growth hormone could be isolated from its insulin-antagonizing effects. In work published in 1993, Wu and Ng demonstrated that a synthetic version of the hGH C-terminal sequence spanning residues 177 to 191 reproduced the antilipogenic activity of intact growth hormone in rat adipose tissue. A companion study by Wijaya and Ng in the same year showed the fragment also reduced insulin-stimulated glucose transport in rat adipocytes, consistent with hGH's overall metabolic signature. Metabolic Pharmaceuticals, an Australian biotechnology company, subsequently developed a stabilized version of this fragment by adding a tyrosine residue at the N-terminus — the molecule designated AOD-9604 — and pursued it as an obesity drug candidate.

Proposed mechanism

Full-length human growth hormone stimulates lipolysis (the breakdown of stored fat into free fatty acids) and inhibits lipogenesis (the conversion of glucose into fat) through activation of MEK-ERK and other downstream pathways. A 2020 review by Kopchick, Berryman, Puri, and colleagues established that GH's adipose effects operate largely through these pathways and are accompanied by whole-body insulin resistance — a known liability of chronic GH exposure. The hypothesis behind AOD-9604 was that the C-terminal fragment might retain the fat-metabolism activity while bypassing the hGH receptor interaction responsible for the diabetogenic side effects. Preclinical characterization published by Ng and colleagues in Hormone Research in 2000 described AOD-9604 specifically: the tyrosine-stabilized fragment reduced weight gain in obese Zucker rats without adversely affecting insulin sensitivity. A companion paper by Ng and colleagues in the Journal of Molecular Endocrinology in 2000 characterized the closely related fragment AOD9401 in the same Zucker rat model and reported reductions in body-weight gain and adipocyte size without glucose intolerance, reinforcing the claim that the antilipogenic activity of the hGH C-terminal domain could be separated from the diabetogenic effects of the full-length hormone. A structural analysis by Ogru and colleagues, published in the Journal of Peptide Research in 2000, confirmed a lipolysis-stimulating, lipogenesis-inhibiting profile. Research by Heffernan, Jiang, Thorburn, and Ng published in the American Journal of Physiology — Endocrinology and Metabolism in 2000 demonstrated that oral administration of a synthetic hGH fragment reduced weight gain in obese animals through mechanistic activity in adipose tissue. A follow-on study by Heffernan and colleagues published in 2001 in Endocrinology tested AOD-9604 in both obese and beta-3-adrenergic-receptor knockout mice and showed evidence that the fragment's lipolytic activity does not require the standard hGH receptor, suggesting a distinct cellular pathway. Whether that pathway operates the same way in humans remained unresolved.

What the preclinical and human evidence shows

The preclinical evidence for AOD-9604's lipid-metabolism effects is substantive by the standards of early drug development. Multiple rodent studies from independent investigators consistently showed reduced fat mass, increased fat oxidation, and reduced body weight gain without signs of glucose intolerance. An early in-vivo study by Natera, Jiang, and Ng published in Biochemistry and Molecular Biology International in 1994 showed that chronic administration of synthetic hGH 177-191 reduced cumulative body weight gain and adipose tissue mass in obese mice. A 2001 paper by Heffernan and colleagues in the International Journal of Obesity and Related Metabolic Disorders showed chronic treatment increased fat oxidation and reduced weight gain in obese mice. However, as Berryman and List noted in a 2017 review published in the International Journal of Molecular Sciences, the relationship between growth hormone and adipose tissue involves complex trade-offs between fat-mass reduction, lean-mass preservation, and metabolic risks — complexity that the rodent models did not fully capture. When the compound reached adequately powered human trials, the results were different from what the preclinical data predicted.

What the Human Evidence Looks Like

How many human studies exist

The primary human data for AOD-9604 centers on a Phase 2b obesity trial conducted by Metabolic Pharmaceuticals, with results reported around 2007. Earlier Phase 2a work, documented by Wilding in a 2004 investigational-drug profile published in Current Opinion in Investigational Drugs, confirmed that Metabolic had advanced AOD-9604 into clinical trials by 2002 based on the preclinical weight-reduction data. Halford, in a 2006 review in the same journal, placed AOD-9604 in context with the broader late-2000s obesity drug pipeline — a pipeline that proved to produce mostly failed candidates. Zieba, writing in Postępy Higieny i Medycyny Doświadczalnej in 2007, reviewed antiobesity drugs then in clinical development and grouped AOD-9604 among the investigational candidates moving through the 2000s obesity pipeline ahead of the Phase 2b readout. The Phase 2b trial represented the pivotal test of the compound's clinical efficacy.

What those studies measured and the Phase 2b failure

The Phase 2b obesity trial is the central fact about AOD-9604's clinical history, and it must not be obscured. The trial was adequately powered, placebo-controlled, and designed to detect weight loss over 24 weeks. It failed to meet its primary weight-loss endpoint versus placebo. A 2013 review by Misra in Current Cardiology Reviews documented that development of AOD-9604 was terminated in 2007 after a 24-week Phase 2b trial in 536 subjects failed to induce significant weight loss, despite an earlier 12-week trial showing a 2.6 kg vs. 0.8 kg placebo weight reduction. The primary publication from the pivotal Phase 2b trial was never submitted to a peer-reviewed journal — the failure is documented via the Misra review and company disclosures. Following the Phase 2b outcome, Metabolic Pharmaceuticals did not advance AOD-9604 to Phase 3 trials. The Australian Therapeutic Goods Administration rejected an obesity indication. The compound received GRAS (Generally Recognized As Safe) status from the FDA for use as a dietary supplement ingredient — a designation that speaks to safety profile but says nothing about therapeutic efficacy. The lipolytic mechanism observed in rodents did not translate to statistically significant weight loss in the one adequately powered human trial.

Regulatory and Legal Status

FDA classification and Category 2 status

As of April 2026, AOD-9604 is classified as an FDA Category 2 bulk drug substance. Category 2 substances are those under evaluation by the FDA's Pharmacy Compounding Advisory Committee, where compounding is restricted pending further review. This classification does not mean the compound has been found unsafe — it means the FDA has not yet made a final determination on its eligibility for compounding under Section 503A. AOD-9604 has never held an FDA-approved drug indication. The prior availability of AOD-9604 through compounding pharmacies in the United States operated in a gray area that the February 2026 reclassification actions clarified by restricting compounding of Category 2 substances. Vanhee and colleagues, in a 2014 paper published in Drug Testing and Analysis, documented that AOD-9604 was circulating as an unregulated injectable product in Belgium despite having no drug approval — a pattern that the FDA and international regulators have worked to address.

What would need to change for availability to resume

For AOD-9604 to become available through U.S. compounding pharmacies, the FDA would need to move it from Category 2 to Category 1 status following completion of its evaluation — which would require either sufficient safety and clinical data, or a determination that the compound meets the criteria for compounding eligibility without established efficacy. A manufacturer could also seek a new drug application by designing trials that meet current FDA endpoints, but given the Phase 2b failure in obesity and the absence of an approved indication in any market, this pathway faces significant evidentiary and commercial hurdles. State-level variation in compounding pharmacy regulations adds additional complexity.

WADA and sport ban status

As of the 2026 WADA Prohibited List, AOD-9604 is prohibited in sport. Cox and colleagues, in a 2015 paper in Drug Testing and Analysis, confirmed the compound's structure and WADA-banned status and described a stable metabolite for urine detection. A companion study by Orlovius and colleagues published in Drug Testing and Analysis in 2013 demonstrated that AOD-9604 does not register on the WADA hGH isoform immunoassay, consistent with the compound's proposed mechanism of acting independently of the standard hGH receptor pathway. Competitive athletes subject to WADA testing should be aware that the compound is detectable by sport anti-doping laboratories.

What this means practically

As of April 2026, AOD-9604 cannot be legally obtained through compounding pharmacies in the United States under the restrictions associated with Category 2 classification. Products marketed as AOD-9604 and sold through online vendors operate outside FDA oversight. Independent testing of unregulated peptide products has documented contamination, incorrect dosing, and misidentified compounds in products sold outside licensed pharmacy channels. The absence of regulated manufacturing oversight means the identity, purity, and potency of gray-market injectables cannot be assumed.

Comparators and Alternatives

AOD-9604's most instructive comparator in the GH-axis fat-metabolism category is tesamorelin, which succeeded where AOD-9604 did not. Tesamorelin is a stabilized analog of full-length growth hormone-releasing hormone (GHRH). Falutz, Allas, Blot, and colleagues published a landmark Phase 3 randomized controlled trial in the New England Journal of Medicine in 2007, demonstrating that tesamorelin produced a 15.2% reduction in visceral adipose tissue over 26 weeks in HIV-infected patients with lipodystrophy, with improvements in triglycerides and body image. A pooled Phase 3 analysis by Falutz, Mamputu, Potvin, and colleagues published in the Journal of Clinical Endocrinology and Metabolism in 2010 showed sustained visceral fat reduction and lipid improvement over 52 weeks without clinically meaningful adverse metabolic effects. Stanley, Feldpausch, Oh, and colleagues published a randomized controlled trial in JAMA in 2014 showing tesamorelin significantly reduced both visceral adipose tissue and liver fat in HIV patients over six months. Stanley, Fourman, Feldpausch, and colleagues, in a 2019 Lancet HIV trial, further reported that tesamorelin reduced hepatic fat fraction in HIV-associated non-alcoholic fatty liver disease, with 35% of treated participants achieving normal liver fat versus 4% on placebo. Tesamorelin's trial success does not validate AOD-9604 — these are distinct molecular entities with different mechanisms and very different evidence bases. The contrast is clinically instructive: the GH-axis fat-loss category is not categorically failed; the specific compound that failed is AOD-9604. This comparison is for scientific context only. These compounds have fundamentally different regulatory statuses and evidence bases.

Regarding GLP-1 receptor agonists: AOD-9604 and GLP-1 agonists (semaglutide, tirzepatide) operate through entirely different mechanisms and have nothing structurally or functionally in common. The GLP-1 category has robust Phase 3 human efficacy data. AOD-9604 does not. No meaningful comparison between these compound classes is warranted based on the available evidence.

A Secondary Research Direction: Cartilage and Joint Repair

Following the Phase 2b obesity failure, investigators examined whether AOD-9604's mechanistic profile might be relevant outside weight loss. The most cited work in this direction is an animal study by Kwon and Park, published in the Annals of Clinical and Laboratory Science in 2015, in which 32 New Zealand white rabbits with collagenase-induced knee osteoarthritis (2 mg type II collagenase intra-articularly, twice) were randomized to weekly ultrasound-guided intra-articular injections of saline, 6 mg hyaluronic acid, 0.25 mg AOD-9604, or the combination over 4 to 7 weeks; AOD-9604 alone enhanced cartilage regeneration versus saline, and the AOD-9604 plus HA combination outperformed either agent alone on histologic and functional endpoints. The combination of AOD-9604 plus hyaluronic acid outperformed either agent alone. Rahman, Lee, and Seeds, writing in JAAOS Global Research and Reviews in 2026, grouped AOD-9604 with growth-hormone secretagogues such as ipamorelin, CJC-1295, tesamorelin, and sermorelin as IGF-1 and satellite-cell-signaling candidates of potential interest in orthopaedics, while emphasizing the "current lack of clinical trials" as the defining limitation of this category. These findings are preclinical. No human randomized trial of AOD-9604 for osteoarthritis, cartilage repair, or any orthopaedic indication has been published. The cartilage data should be read as hypothesis-generating animal work, not as clinical evidence for joint use.

Safety: What Is and Is Not Known

Clinical safety data

AOD-9604 received GRAS status for dietary supplement use, reflecting a determination that it is safe at the doses studied for that application. Within the Phase 2b obesity trial, the compound did not produce the glucose-intolerance effects associated with full-length hGH — a finding consistent with the preclinical data and with the proposed mechanism of acting independently of the hGH receptor. However, as Mendias and Awan noted in a 2026 narrative review published in Sports Medicine, unapproved peptides marketed direct-to-patient show favorable preclinical data but "rigorous human safety data are scarce, and there is potential for serious harm." No chronic toxicology data, no reproductive toxicity studies, and no long-term human safety data beyond the Phase 2b trial exist in the published literature.

Risks from unregulated sources

Products sold as AOD-9604 through online vendors and gray-market channels are not subject to pharmaceutical-grade manufacturing standards. They have not been evaluated by the FDA for safety, efficacy, or quality. The Obesity Medicine Association's 2024 position-statement FAQ, authored by Bays, Fitch, Brown, and colleagues and published in Obesity Pillars, called for stakeholder action on the confusion created by unapproved peptides in obesity care and emphasized that clinician and patient confusion about unregulated products poses genuine safety risks. Contamination, dosing inconsistency, and misidentification are documented concerns with gray-market injectable products of this type, as documented in the Vanhee 2014 case report.

Who Should Not Use AOD-9604

Based on AOD-9604's proposed mechanisms, the following groups face elevated theoretical risk. Because no comprehensive human safety data exists, this list is not exhaustive. A licensed provider would need to evaluate individual risk factors before any clinical use were undertaken.

• Active or history of hormone-sensitive malignancy: Any compound that interacts with growth hormone-related signaling pathways carries theoretical concern regarding proliferative effects in individuals with a history of hormone-sensitive cancers. This has not been specifically studied for AOD-9604 in humans.
• Pregnancy and breastfeeding: Safety has not been established. No reproductive toxicity data exists for AOD-9604.
• Competitive athletes subject to anti-doping rules: AOD-9604 is WADA-prohibited and detectable in urine. Use would result in a doping violation.
• Individuals with active metabolic or endocrine disorders: The compound acts on adipose tissue through pathways related to growth hormone signaling. Individuals with pre-existing metabolic disorders should not use unregulated compounds without clinical supervision.
• Anyone seeking access through unregulated online channels: Products sold outside licensed pharmacy channels carry contamination and dosing risks that cannot be mitigated by the end user.

Which Biomarkers Are Relevant if You Are Exploring GH-Axis Fat Metabolism?

Understanding baseline metabolic biology is a reasonable step regardless of which compounds are accessible. For anyone interested in GH-axis influences on fat metabolism — whether or not any specific peptide is available — these markers provide objective context about where you currently stand.

• IGF-1: The primary downstream marker of growth hormone activity. IGF-1 levels reflect the integrated GH secretory pattern over days, not single GH pulses, making it the most clinically useful marker for assessing the GH axis at baseline. Context: AOD-9604 was designed to avoid stimulating IGF-1 elevation, but a baseline reading establishes whether the GH axis is functioning normally before any intervention.
• Fasting glucose: Full-length hGH is known to antagonize insulin signaling. A baseline fasting glucose measurement establishes whether insulin sensitivity is already a concern — relevant context for evaluating any compound that intersects with GH-related pathways.
• Triglycerides: One of the most directly relevant metabolic markers for a compound studied in the context of fat oxidation. Triglycerides reflect the liver's management of fatty acids and are sensitive to changes in fat metabolism, diet, and activity. Tesamorelin, the GH-axis peptide that did succeed in human trials, showed meaningful triglyceride improvements in Phase 3 data — making this a relevant reference marker for the GH-axis fat-metabolism category broadly.
• HbA1c: A 90-day average of blood glucose reflecting longer-term insulin sensitivity. Useful alongside fasting glucose to characterize the full metabolic baseline, particularly when assessing any compound that interacts with GH-related pathways where insulin resistance is a theoretical concern.
• Fasting lipid panel (including HDL, LDL, and total cholesterol): Lipid parameters provide context for fat metabolism at the whole-body level. Changes in fat oxidation, if they occurred, would be expected to influence these markers over time. Baseline values are necessary for interpreting any subsequent changes.
• hs-CRP: High-sensitivity C-reactive protein as a systemic inflammation marker is useful for anyone exploring metabolic interventions. Adipose tissue is an active inflammatory organ, and chronic low-grade inflammation is associated with adiposity and metabolic dysfunction.

The Bottom Line

AOD-9604 represents a scientifically credible hypothesis — a growth hormone fragment engineered to retain lipid-metabolism activity without hGH's diabetogenic effects — that was not supported by the pivotal human trial. The preclinical evidence is real; the Monash University research group produced rigorous mechanistic work across multiple studies. The failure of the Phase 2b obesity trial to meet its primary endpoint versus placebo is also real, and it is the most important single fact about this compound. The compound's current Category 2 classification reflects an incomplete regulatory process, not a resolution. Understanding what is and is not known about the GH axis — through objective biomarker data — provides a more durable foundation for clinical decisions than the status of any single compound at any given moment.

That principle is central to Superpower's approach to preventive health: objective biomarker data should inform every clinical decision, whether the compound in question is available today or still working through regulatory review.

IMPORTANT SAFETY INFORMATION

AOD-9604 is not FDA-approved for any indication. It is currently classified as an FDA Category 2 bulk drug substance; compounding under Section 503A is restricted pending further FDA review. AOD-9604 received GRAS (Generally Recognized As Safe) status for dietary supplement use only — this status does not constitute FDA approval for therapeutic use or validation of clinical efficacy. Superpower is a technology platform that connects members with licensed healthcare providers and testing services. Superpower does not prescribe or dispense medications and does not currently offer or facilitate access to AOD-9604.

The Phase 2b human obesity trial of AOD-9604 did not meet its primary weight-loss endpoint versus placebo. Human safety and efficacy for therapeutic indications have not been established through adequate and well-controlled clinical trials.

Contraindications: Do not use if you are a competitive athlete subject to WADA anti-doping rules (AOD-9604 is on the WADA Prohibited List and detectable in urine). Do not use if you have a history of hormone-sensitive malignancy. Do not use if pregnant or breastfeeding (reproductive safety not established). Do not obtain from unregulated online sources — gray-market injectable products lack pharmaceutical-grade manufacturing oversight.

Warnings: No chronic toxicology data or long-term human safety data exist beyond the Phase 2b trial. No reproductive toxicity studies have been published. Products sold outside licensed pharmacy channels carry contamination and dosing risks. The compound's interaction with growth hormone-related signaling pathways has not been fully characterized in humans.

Common side effects reported in clinical context: No systematic adverse event profile has been published from the Phase 2b trial. GRAS safety data at dietary supplement doses did not identify significant adverse effects. Long-term side effects at any dose are unknown.

As of April 2026, no completed human efficacy trials for AOD-9604 exist beyond the failed Phase 2b obesity study. Data from animal models cannot be extrapolated to confirm efficacy in humans. Full compound reference data available at PubChem CID 10270282.

Additional Questions

Can a doctor still prescribe AOD-9604?

As of April 2026, AOD-9604's Category 2 classification restricts its compounding under Section 503A, meaning it is not available through the licensed compounding pharmacy pathway that previously distributed it. There is no FDA-approved drug formulation of AOD-9604 that a licensed prescriber can prescribe. Whether prescribing through alternative pathways is possible would depend on specific state regulations and should be directed to a licensed healthcare provider.

What is the FDA Category 2 peptide list, and will these compounds become available again?

FDA Category 2 designates bulk drug substances under evaluation by the Pharmacy Compounding Advisory Committee, where compounding is restricted while the evaluation is pending. For a Category 2 compound to become available through compounding, the FDA would need to reclassify it to Category 1 following completion of its review — a process that depends on the availability of adequate safety and clinical data, the regulatory record, and the FDA's determination of compounding eligibility. The timeline for any specific compound's reclassification is not publicly established, and no guarantees exist that Category 2 compounds will be reclassified.

What is the difference between AOD-9604 and tesamorelin?

These are structurally unrelated compounds that target fat metabolism through different mechanisms. Tesamorelin is a stabilized GHRH analog that stimulates the pituitary to release endogenous growth hormone. AOD-9604 is a synthetic C-terminal fragment of hGH itself, proposed to act on adipose tissue directly without stimulating pituitary GH release. Tesamorelin has FDA approval for HIV-associated lipodystrophy, supported by multiple Phase 3 randomized controlled trials including the Falutz and colleagues 2007 NEJM study. AOD-9604 has no FDA-approved indication and failed its Phase 2b obesity trial. This comparison is for scientific context only. These compounds have fundamentally different regulatory statuses and evidence bases.