AOD-9604: The HGH Fragment 176-191 Research Profile — Lipolysis, Cartilage Repair, and Metabolic Selectivity

What Is AOD-9604?

AOD-9604 (Anti-Obesity Drug 9604) is a synthetic 16-amino-acid peptide corresponding to the C-terminal fragment of human growth hormone (residues 176-191), with a tyrosine substitution at the N-terminus replacing the native phenylalanine. With a molecular weight of approximately 1815 Da, it was engineered by researchers at Monash University (Melbourne, Australia) in the 1990s with a specific goal: isolate the lipolytic (fat-mobilizing) properties of growth hormone while eliminating the growth-promoting, IGF-1-elevating, and diabetogenic effects associated with full-length HGH.

For dosing, reconstitution, and protocol details, see our AOD-9604 / HGH Fragment 176-191 Dosage Protocol Guide — Reconstitution, Administration & Research Protocols (2026).

The peptide's official sequence is Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe, with a disulfide bridge between the two cysteine residues (positions 7 and 14 in the fragment) that mirrors a structural feature of the parent molecule and is thought to contribute to receptor selectivity.

Unlike the growth hormone secretagogues (GHRP-6, Ipamorelin, CJC-1295), which trigger pituitary release of endogenous GH, AOD-9604 acts directly on peripheral adipose tissue. This direct mechanism bypasses the hypothalamic–pituitary axis entirely, making it a distinct research tool for studying fat metabolism independently from the broader anabolic and somatotropic effects that complicate full-GH research.

Structure and Chemistry

Amino Acid Sequence

AOD-9604 is a bicyclic peptide fragment. The full-length human growth hormone (191 amino acids) contains a C-terminal domain responsible for metabolic activity that is structurally separable from the N-terminal domain associated with receptor binding, growth promotion, and IGF-1 stimulation. By isolating and synthesizing residues 176–191 with the N-terminal tyrosine modification, researchers created a peptide that retains the metabolic fingerprint of GH without the anabolic payload.

The disulfide bridge between Cys-7 and Cys-14 (within the fragment numbering) creates a rigid, cyclic conformation. This structural constraint is believed to be important for receptor interaction — in particular, the engagement of beta-3 adrenergic receptors on adipocytes. Linear analogs lacking this bridge show reduced activity in preclinical models.

Physical Properties

Mechanism of Action: Selective Lipolysis Without GH Side Effects

Beta-3 Adrenergic Receptor Upregulation

The primary mechanism through which AOD-9604 exerts its effects on adipose tissue involves the beta-3 adrenergic receptor (β3-AR), a G-protein coupled receptor expressed predominantly in brown and white adipose tissue. β3-AR activation is a well-established trigger for lipolysis and thermogenesis, and its suppression in obesity is thought to contribute to reduced fat mobilization in obese individuals.

Research published in Endocrinology (Heffernan et al., 2001) demonstrated that both full-length human GH and AOD-9604 significantly increased β3-AR RNA expression in adipose tissue of obese mice, effectively restoring suppressed receptor levels toward those observed in lean controls. This normalization of β3-AR expression is a mechanistically distinct action from simply flooding the circulation with growth hormone.

The critical role of β3-AR was confirmed through a knockout experiment: when β3-AR was genetically removed from mice, chronic AOD-9604 treatment produced no measurable changes in body weight, fat mass, or lipolysis. This demonstrated that the β3-AR pathway is not merely contributory but required for AOD-9604's metabolic effects.

The cAMP–PKA–HSL Signaling Cascade

Once β3-AR is activated by AOD-9604, it couples to the stimulatory G-protein (Gαs), triggering adenylyl cyclase to convert ATP to cyclic AMP (cAMP). This second messenger accumulates within the adipocyte and activates protein kinase A (PKA), a serine/threonine kinase with broad downstream effects.

PKA's most relevant substrate in this context is hormone-sensitive lipase (HSL) — the primary intracellular lipase responsible for hydrolyzing stored triglycerides into diglycerides, monoglycerides, and ultimately free fatty acids plus glycerol. PKA phosphorylates HSL at key serine residues (Ser-563 and Ser-660), causing its translocation from the cytosol to lipid droplet surfaces and a 10- to 100-fold increase in enzymatic activity.

The resulting free fatty acids exit the adipocyte and enter circulation as a fuel source for peripheral tissues, including skeletal muscle and the liver. In animal studies, AOD-9604 treatment increased fat oxidation markers and reduced respiratory quotient values, consistent with enhanced lipid utilization relative to carbohydrate metabolism.

Inhibition of Lipogenesis via Acetyl-CoA Carboxylase

Beyond stimulating fat breakdown, AOD-9604 simultaneously inhibits lipogenesis — the synthesis of new fatty acids from precursors. Mechanistically, this appears to involve downregulation of acetyl-CoA carboxylase [PMID 11146367] (ACC), the rate-limiting enzyme in fatty acid biosynthesis. ACC catalyzes the conversion of acetyl-CoA to malonyl-CoA, the first committed step in de novo lipogenesis. When AOD-9604 reduces ACC activity, this dual action — increasing fat breakdown while decreasing fat synthesis — creates a net negative fat balance in adipose tissue under research conditions.

This dual mechanism is believed to be the reason AOD-9604 produced greater fat loss than placebo in early animal studies: not merely by mobilizing existing fat faster, but by limiting the resynthesis that would otherwise partially offset lipolytic gains.

GH Receptor Independence

A critical distinction from full-length HGH is that AOD-9604 does not bind to or activate the classical growth hormone receptor (GHR). The GHR is responsible for mediating virtually all of GH's anabolic, growth-promoting, and insulin-sensitizing (or desensitizing) effects. By bypassing GHR entirely, AOD-9604 avoids:

• •IGF-1 elevation (and associated mitogenic/proliferative effects)
• •Sodium and water retention
• •Insulin resistance and potential pro-diabetic effects
• •Bone and soft tissue proliferation
• •Carpal tunnel syndrome and joint pain associated with GH excess

This selectivity profile made AOD-9604 an attractive research candidate in the 2000s for obesity management in populations where GH-related side effects would be unacceptable.

Preclinical Research Evidence

Obese Mouse Models

The preclinical evidence base for AOD-9604 is most robust in rodent models of diet-induced obesity. A landmark study by Ng et al. (2001) in the International Journal of Obesity compared chronic administration of full-length HGH versus AOD-9604 in obese mice. Both compounds produced statistically significant reductions in body weight and fat mass relative to untreated controls, and the magnitude of fat loss was comparable between groups — despite AOD-9604 carrying none of HGH's anabolic activity.

Importantly, obese mice treated with AOD-9604 showed increased fat oxidation rates as measured by indirect calorimetry, without changes in food intake or energy expenditure through non-lipid pathways. This supported the hypothesis that the compound acts specifically on stored fat rather than inducing systemic hypermetabolism.

β3-AR Knockout Mice: Mechanistic Proof

As described in the Heffernan 2001 paper, mice genetically engineered to lack β3-AR showed no metabolic response to AOD-9604 at doses effective in wild-type animals. This mechanistic validation is scientifically important: it confirms that AOD-9604's effects are not mediated by a yet-to-be-identified receptor, and gives researchers a clear pharmacological target for investigating downstream interventions.

Cartilage and Chondrocyte Research

Beyond fat metabolism, AOD-9604 has been investigated in models of cartilage repair. A study by Thompson and colleagues, later tested in a collagenase-induced rabbit knee osteoarthritis model (Chiang et al., Annals of Clinical and Laboratory Science, 2015), explored whether intra-articular injection of AOD-9604 — alone or in combination with hyaluronic acid (HA) — could promote cartilage matrix regeneration.

Key findings included:

• •AOD-9604 alone produced measurable increases in cartilage matrix production in vitro and in vivo
• •Combined AOD-9604 + HA injections outperformed either agent alone on histological cartilage scoring
• •The combination showed superior suppression of inflammatory markers in synovial fluid compared to HA-only controls
• •No systemic adverse effects were attributed to intra-articular AOD-9604

These results positioned AOD-9604 as a potential adjunct in osteoarthritis management in animal models. However, researchers caution that rabbit models of OA are significantly simpler than human disease progression, and the path from these results to validated clinical use involves substantial additional investigation.

Clinical Development History

Phase I and Phase II Trials (Oral Administration)

Metabolic Pharmaceuticals, the Australian company that licensed AOD-9604 from Monash University, conducted six randomized, double-blind, placebo-controlled trials between 2001 and 2007, testing oral formulations at doses of 0.25 mg, 0.5 mg, and 1 mg per day. The choice of oral administration was clinically motivated — a pill formulation would be far more commercially viable than injectable GH therapies.

The Phase I program established a favorable safety profile. Across multiple dose cohorts, AOD-9604 showed tolerability indistinguishable from placebo, with no serious adverse events attributed to the compound and no participants withdrawing due to AOD-9604-related side effects. Critically, oral AOD-9604 did not elevate IGF-1, did not affect blood glucose or insulin levels, and did not produce any of the cardinal GH side effects (edema, arthralgia, carpal tunnel syndrome).

An early Phase II trial demonstrated that subjects receiving AOD-9604 lost an average of 1.8 kg more than placebo subjects over 12 weeks. This initial signal was promising enough to justify a larger, longer Phase IIb study.

Phase IIb: The Pivotal Trial and Discontinuation

The pivotal Phase IIb trial enrolled approximately 300 overweight adults in a 24-week protocol. Unfortunately, this trial failed to replicate the earlier weight loss signal at statistically significant levels. The primary endpoint — clinically meaningful reduction in body weight versus placebo — was not met, and Metabolic Pharmaceuticals discontinued further obesity drug development in 2007.

Several hypotheses exist for the disconnect between early-phase results and the pivotal trial:

1. Dose optimization: The oral doses tested may not have produced sufficient systemic exposure at the receptor level in a larger, more heterogeneous population.

2. Disease heterogeneity: Obesity is a metabolically diverse condition; β3-AR-dependent lipolysis may be more relevant in specific phenotypic subgroups.

3. Route-of-delivery limitation: The oral route introduces variable bioavailability due to intestinal peptidase degradation, and subcutaneous delivery (the route used in most post-trial research contexts) was not formally evaluated in the clinical program.

Nutraceutical Designation and GRAS Research

Following the drug development program's closure, the AOD-9604 IP was repositioned toward the nutraceutical market. A 2014 study published in the Journal of Endocrinology and Metabolism (Moré et al., 2014) evaluated safety and metabolism specifically to support GRAS (Generally Recognized As Safe) consideration. Results confirmed:

• •Oral bioavailability was demonstrated in pig plasma via mass spectrometry following oral dosing
• •No genotoxic activity in Ames test, chromosomal aberration assay, or bone micronucleus assay
• •Chronic oral administration in rats and cynomolgus monkeys showed no toxicological concerns at multiples of the proposed human intake dose

Despite these findings, the FDA's current position classifies AOD-9604 as a bulk drug substance that may present safety risks when used in compounded preparations, and it does not hold approved drug, dietary supplement, or food ingredient status in the United States.

Australian TGA Classification

Australia's Therapeutic Goods Administration (TGA) classifies AOD-9604 as a Schedule 4 substance under the Poisons Standard, meaning it requires a valid prescription from a licensed medical practitioner for legal acquisition and use. This prescription-only status reflects the TGA's determination that AOD-9604 carries sufficient pharmacological activity to warrant medical oversight, despite its exploratory status elsewhere.

Australian compound pharmacies have dispensed AOD-9604 under TGA's Special Access Scheme (SAS) and Authorized Prescriber pathways, primarily for weight management and, more recently, osteoarthritis-adjacent applications. The TGA's scheduling decision is not equivalent to product approval — it establishes a regulatory category without endorsing specific clinical indications.

An Adelaide University researcher, commenting in the context of the TGA review process, noted that clinical evidence supporting tissue repair benefits in humans remained limited at that time, emphasizing that animal model data should not be extrapolated directly to human therapeutic claims.

Safety Profile and Metabolic Advantages

No Hyperglycemia or Insulin Resistance

One of the most clinically relevant safety findings across the AOD-9604 research program is the absence of diabetogenic effects. Full-length growth hormone at pharmacological doses inhibits insulin action and can precipitate type 2 diabetes in predisposed individuals — a major limiting factor in GH therapy. AOD-9604, by bypassing the GH receptor, produced no measurable changes in fasting blood glucose, insulin sensitivity, or HbA1c markers across clinical trial participants.

This distinguishes AOD-9604 sharply from recombinant HGH and makes it a more tractable research tool for metabolic studies in models where insulin resistance is a confounding variable.

No IGF-1 Elevation

Insulin-like growth factor 1 (IGF-1) mediates many of GH's growth-promoting and potentially pro-oncogenic effects. Elevated IGF-1 has been associated in epidemiological studies with increased risks of certain cancers (notably prostate and colorectal), and chronic IGF-1 elevation is a concern with long-term GH therapy. AOD-9604 consistently showed no effect on circulating IGF-1 levels in all Phase I and Phase II clinical trials, as well as preclinical models.

For researchers investigating fat metabolism as an isolated endpoint, AOD-9604 therefore provides a cleaner experimental tool — one that doesn't introduce the IGF-1 signaling noise that would complicate interpretation of results.

No Appetite Suppression

Unlike GLP-1 agonists such as semaglutide, which primarily drive weight loss through central appetite suppression, AOD-9604 produces no measurable changes in food intake or satiety signaling. Animal studies confirmed that caloric consumption remained unchanged between AOD-9604-treated and placebo groups, with all fat mass differences attributable to altered lipid metabolism rather than reduced energy input.

This mechanistic distinction makes AOD-9604 a research tool that can study fat mobilization independently from feeding behavior — valuable for researchers trying to dissect specific metabolic pathways.

Adverse Effects in Clinical Research

Across the clinical trials and preclinical studies, the reported adverse effect profile of AOD-9604 was consistently minimal:

• •No serious adverse events attributed to AOD-9604
• •No withdrawals due to drug-related adverse effects
• •No effects on pituitary function or GH/IGF-1 axis
• •No changes in thyroid, adrenal, or gonadal hormone levels
• •Injection site reactions (redness, mild discomfort) reported at subcutaneous administration sites in post-trial community protocols

The apparent safety of AOD-9604 in human studies reflects its high receptor specificity — by engaging only β3-AR in adipose tissue without binding to GHR, GnRH receptors, or other neuroendocrine targets, systemic off-target effects are limited.

Research Protocols and Dosing

Important Disclaimer

The following information reflects dosing parameters used in preclinical research and community-derived research protocols. AOD-9604 is not approved by the FDA or any major regulatory body for therapeutic use in humans. All protocols are for research purposes only, and any human use should occur under direct medical supervision. This material does not constitute medical advice.

Clinical Trial Dosing (Oral)

The formal clinical program tested oral AOD-9604 at:

• •0.25 mg/day (250 mcg) — low-dose cohort
• •0.5 mg/day (500 mcg) — mid-dose cohort
• •1 mg/day (1000 mcg) — high-dose cohort

All doses were administered in the morning, fasted or with a light breakfast. The 12-week Phase II trial showing 1.8 kg additional weight loss versus placebo used the 0.5 mg/day dose.

Subcutaneous Research Protocol

Current subcutaneous protocols used in research contexts are not directly derived from the clinical trials (which tested oral administration) but have been developed through post-trial research community practice. Common parameters include:

• •Dose range: 200–500 mcg per injection
• •Frequency: Once daily (morning, fasted state)
• •Route: Subcutaneous injection, typically abdomen or upper thigh
• •Cycle length: 8–12 weeks
• •Titration approach: Many researchers begin at 200–300 mcg for the first 2–4 weeks, increasing to 400–500 mcg if well tolerated

The morning fasted state is chosen because β3-AR-mediated lipolysis is more active when circulating insulin levels are low. Feeding triggers insulin secretion, which activates phosphodiesterase enzymes that break down cAMP — the intracellular second messenger that AOD-9604 relies upon for its signaling cascade. Elevated insulin therefore attenuates AOD-9604's mechanism at the adipocyte level.

Pharmacokinetics

• •Half-life (IV): Approximately 3–4 minutes in plasma following intravenous administration
• •Downstream duration: Receptor-level and downstream enzymatic effects persist for an estimated 12–24 hours following plasma clearance
• •Oral bioavailability: Demonstrated in pig plasma via MS analysis; protracted absorption profile versus injection due to intestinal peptidase activity
• •Subcutaneous absorption: More gradual than IV; peak plasma concentrations typically within 30–60 minutes post-injection

Note that the very short plasma half-life after IV dosing reflects rapid enzymatic degradation of the peptide in circulation. The downstream signaling effects outlast the parent compound because cAMP accumulation and PKA activation persist after the initial receptor stimulation.

Reconstitution and Handling

For subcutaneous research use, lyophilized AOD-9604 is typically reconstituted with bacteriostatic water:

• •Add 1–2 mL of bacteriostatic water per 5 mg vial using an insulin syringe
• •Swirl gently (do not shake vigorously — peptide bonds can be disrupted by mechanical shear)
• •Store reconstituted solution at 2–8°C
• •Reconstituted AOD-9604 is typically stable for 4–6 weeks refrigerated
• •Protect from light; UV exposure degrades the disulfide bridge

AOD-9604 Compared to Other Weight-Management Research Peptides

vs. Full-Length HGH

Full-length recombinant HGH (191 amino acids) activates GHR and drives both fat mobilization and a broad anabolic program including IGF-1 elevation, protein synthesis, skeletal growth, sodium retention, and insulin resistance. AOD-9604 fragments out the lipolytic component while eliminating all GHR-mediated signaling. This makes AOD-9604 a more specific research tool for studying fat metabolism in isolation, though at the expense of the systemic metabolic improvements that GH can produce (including increased lean mass, which improves resting metabolic rate).

For researchers studying the relationship between fat mass, growth factors, and metabolic disease, AOD-9604 and HGH are complementary rather than interchangeable compounds.

vs. GH Secretagogues (CJC-1295, GHRP-6, Ipamorelin, Sermorelin)

Growth hormone secretagogues stimulate the pituitary to release endogenous GH. This indirect approach produces a pulsatile GH signal that physiologically mimics natural GH release and, at therapeutic doses, tends to increase both fat oxidation and lean mass simultaneously. Because secretagogues increase endogenous GH, they will also elevate IGF-1 (though typically less dramatically than exogenous HGH at supraphysiological doses).

AOD-9604's direct adipose tissue action bypasses this axis entirely. Researchers comparing the two approaches can use AOD-9604 to model "fat-selective GH activity" and secretagogue stacks to model "physiological GH restoration" — two distinct experimental conditions with different mechanistic implications.

vs. GLP-1 Agonists (Semaglutide, Tirzepatide)

GLP-1 receptor agonists including semaglutide and tirzepatide represent the current standard-of-care for pharmacological obesity management, producing 15–22% body weight reduction in clinical trials. Their mechanism is fundamentally different from AOD-9604: GLP-1 agonists work primarily through central nervous system GLP-1 receptors in the hypothalamus and brainstem to suppress appetite, slow gastric emptying, and reduce caloric intake. Fat loss is largely an indirect consequence of reduced energy consumption rather than direct lipid mobilization.

AOD-9604 produces no appetite changes, does not affect GLP-1 signaling, and has not demonstrated weight loss outcomes remotely comparable to semaglutide in controlled trials. The compounds are mechanistically complementary for research purposes — studying fat mobilization pathways (AOD-9604) versus appetite regulation pathways (GLP-1 agonists) requires different research tools.

vs. MOTS-c

MOTS-c, a mitochondria-derived peptide encoded within the 12S ribosomal RNA gene, influences metabolism through AMPK activation and enhanced glucose uptake in skeletal muscle. It improves insulin sensitivity, increases exercise endurance, and reduces age-associated adiposity in rodent models. While both MOTS-c and AOD-9604 affect fat mass, their mechanisms are orthogonal: MOTS-c acts primarily in muscle through energy-sensing pathways, while AOD-9604 acts in adipose tissue through adrenergic signaling. These non-overlapping mechanisms make them interesting candidates for combination research in metabolic disease models.

vs. 5-Amino-1MQ

5-Amino-1MQ inhibits NNMT (nicotinamide N-methyltransferase), an enzyme overexpressed in adipose tissue of obese individuals that suppresses NAD+ availability and reduces the activity of fat-burning pathways. By inhibiting NNMT, 5-Amino-1MQ increases NAD+ levels, activates SIRT1 (a longevity-associated deacetylase), and promotes fat browning in white adipose tissue. Like AOD-9604, 5-Amino-1MQ targets adipose tissue directly without affecting appetite — but through a completely different enzymatic target. This makes these compounds interesting comparators for researchers studying the multiple regulatory chokepoints in adipose tissue lipolysis.

Current Research Landscape and Regulatory Status

FDA Status

The FDA currently classifies AOD-9604 as a bulk drug substance that may present safety risks when used in compounded preparations. This designation, issued as part of the FDA's 503A compound pharmacy oversight process, means that FDA-regulated pharmacies are restricted from including AOD-9604 in compounded preparations without clear regulatory authorization. The FDA's concern stems not from documented clinical harm but from the compound's uncharacterized risk profile in non-supervised use contexts.

AOD-9604 is not approved as:

• •An FDA-approved drug
• •A dietary supplement (it does not qualify as a conventional food ingredient or vitamin)
• •A food additive

It exists in a regulatory gray zone in the United States — manufactured for research use, classified as a research chemical, and labeled for laboratory or research purposes only.

Australia

As noted, the TGA classifies AOD-9604 as Schedule 4 (prescription only). It is not registered on the Australian Register of Therapeutic Goods (ARTG) for any specific indication, but it can be accessed under SAS Category B for individual patients under specialist physician supervision.

Research Directions

Current areas of AOD-9604 research include:

1. Osteoarthritis and joint repair: Following the promising rabbit model data, researchers are investigating optimal intra-articular dosing, combination protocols with HA, and the molecular mechanism by which AOD-9604 promotes chondrocyte matrix synthesis.

2. Metabolic phenotyping tools: AOD-9604's receptor specificity makes it useful for dissecting β3-AR-dependent lipolysis from other fat-mobilizing pathways in metabolic disease models.

3. Topical and oral delivery systems: Research into nanoparticle encapsulation and modified oral delivery systems aims to improve bioavailability beyond what the original clinical trial formulations achieved.

4. Combination metabolic research: Some investigators explore AOD-9604 in combination with caloric restriction, exercise, or GLP-1 analogs to study whether direct lipolysis induction and appetite suppression have synergistic or additive effects on fat mass reduction.

Researchers sourcing AOD-9604 for these investigations should consult community supplier reviews to evaluate vendor reliability before committing to a long-term supply arrangement.

AOD-9604 Supplier Pricing Comparison (Live Data — August 2026)

Peptides.SO tracks AOD-9604 listings across 60+ active research suppliers. Price range: $0.55–$350 per vial, reflecting wide variation in vial size, concentration, and supplier tier.

Price interpretation: Low-end pricing ($0.55–$5) typically reflects bulk powder or very small vials where cost-per-mg is high. Mid-range ($25–$50) represents standard lyophilized vials with typical COA documentation. Premium pricing ($75+) usually indicates enhanced third-party testing documentation or specialty formats (nasal sprays, larger concentrations). For verified supplier reviews, see the Peptides.SO supplier comparison page.

Frequently Asked Questions: AOD-9604 Research

What is the key mechanistic difference between AOD-9604 and full-length HGH?

AOD-9604 is the C-terminal fragment 176-191 of human growth hormone. Unlike full HGH, it does not bind the growth hormone receptor (GHR) or activate the JAK2/STAT5 pathway responsible for IGF-1 secretion and anabolic effects. Instead, AOD-9604 appears to interact selectively with β-adrenergic receptors in adipose tissue, promoting lipolysis through a GHR-independent mechanism. This selectivity is why preclinical research showed metabolic effects without detectable anabolic or diabetogenic actions in animal models.

Why did the human obesity trials with AOD-9604 fail?

The Phase 2b/3 trials conducted by Metabolic Pharmaceuticals (2000s) did not demonstrate statistically significant weight loss vs. placebo at tested doses in the obese human population. Researchers have suggested several explanations: the dose extrapolation from rodent to human may have been insufficient, the 12-week trial duration may have been too short to detect meaningful differences, or the adipose receptor pharmacology may differ between species. FDA approval was not obtained (AOD-9604 was investigated under IND 59,673). The compound remains of research interest for articular cartilage applications based on separate preclinical findings.

What has research shown about AOD-9604 and cartilage repair?

Independent of the obesity research, studies in rabbit and sheep models have investigated AOD-9604's potential to promote cartilage regeneration. Research published in Osteoarthritis and Cartilage found that intra-articular AOD-9604 promoted chondrocyte anabolism and reduced cartilage degradation in OA models. These findings are mechanistically distinct from its lipolytic actions and involve different tissue targets. No human clinical trials of AOD-9604 for cartilage indications have been published in peer-reviewed literature as of 2026.

How should AOD-9604 be reconstituted for research use?

AOD-9604 is typically supplied as a lyophilized powder and should be reconstituted with bacteriostatic water or sterile water. Standard reconstitution uses 1-2 mL of diluent per 5 mg vial. The peptide is water-soluble at physiological pH and does not typically require acetic acid or DMSO for dissolution. See the Peptide Reconstitution Guide for full protocol details.

Is AOD-9604 the same as Fragment 176-191?

Yes — AOD-9604 and HGH Fragment 176-191 are the same compound and are used interchangeably in research literature. "AOD-9604" is the investigational name used in clinical development by Metabolic Pharmaceuticals; "Fragment 176-191" refers to its position within the 191-amino-acid HGH sequence. Both names appear in supplier catalogs and should refer to the same peptide with sequence: Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (with disulfide bridge between Cys9 and Cys17 in HGH numbering, positions 182 and 189).

Where can I find the Certificate of Analysis for AOD-9604?

Reputable research suppliers provide lot-specific COAs showing HPLC purity (≥98% for research grade), mass spectrometry MW confirmation (theoretical MW: ~1817 Da), and amino acid analysis. When evaluating suppliers, request lot numbers and verify the COA matches your vial. The COA Interpretation Guide explains how to read each section of a peptide COA. Third-party testing from independent labs (Janoshik, Colmaric) provides the highest confidence in compound identity and purity.

Internal Linking Opportunities

Researchers investigating AOD-9604 in the context of broader metabolic peptide research may find the following comparator articles useful:

• •Best Research Peptides for Weight Loss in 2026 — comprehensive overview of the fat-loss peptide research landscape
• •Growth Hormone Secretagogues Compared — detailed comparison of GHRP-6, Ipamorelin, CJC-1295, Sermorelin, and MK-677
• •GLP-1 Receptor Agonists: Complete Research Overview — mechanism and clinical evidence for semaglutide, tirzepatide, liraglutide
• •MOTS-c: Mitochondrial-Derived Peptide for Metabolic Homeostasis — mitochondrial peptide with complementary metabolic mechanisms
• •Peptide Research Dosing Calculator — dosing conversion tool for research applications

Research Supplier Comparison: AOD-9604 Pricing (August 2026)

Peptides.SO indexes 52 suppliers carrying AOD-9604 across 69+ active listings — the HGH fragment commands meaningful market supply relative to newer metabolic research peptides. Pricing is expressed per mg from verified, in-stock listings.

Pricing notes: Entries at <$0.05/mg typically reflect bulk-vial or data-entry outliers and are excluded from the table above. AOD-9604 is sold in 2mg, 5mg, and 10mg vial formats — per-mg cost varies with vial size. For comprehensive live pricing across all variants and suppliers, see the AOD-9604 price comparison page.

> For research use only. AOD-9604 is a research peptide not approved for human therapeutic use. All pricing data is sourced from Peptides.SO's live vendor index as of August 2026.

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Frequently Asked Questions: AOD-9604 Research

Q: What is AOD-9604 and how does it differ from full-length human growth hormone?

A: AOD-9604 (Advanced Obesity Drug 9604) is a synthetic 16-amino-acid fragment corresponding to the C-terminal domain of human growth hormone (hGH), specifically residues 176–191 of the hGH sequence. It contains the lipolysis-regulating region of hGH but lacks the N-terminal domain responsible for binding the GH receptor and mediating anabolic (IGF-1-elevating) effects. In preclinical studies, AOD-9604 reproduces the fat-burning properties of hGH without measurable effects on blood glucose, insulin, or IGF-1 levels — the metabolic and mitogenic effects central to hGH safety concerns.

Q: What is the current research and regulatory status of AOD-9604?

A: AOD-9604 completed Phase II clinical trials in Australia under Metabolic Pharmaceuticals (2001–2004) demonstrating lipid-related activity in obese subjects, then entered Phase IIb/III trials before the development program was discontinued due to commercial rather than safety concerns. The compound received GRAS (Generally Recognized As Safe) status from the FDA in 2014 for use as a food additive — a designation that relates to oral ingestion safety rather than therapeutic approval. AOD-9604 is not FDA-approved as a drug and remains a research compound for preclinical investigation.

Q: How does AOD-9604 stimulate lipolysis at the molecular level?

A: AOD-9604 activates β3-adrenergic receptors on adipocyte cell surfaces, triggering cAMP-mediated activation of hormone-sensitive lipase (HSL). HSL then phosphorylates stored triglycerides, releasing free fatty acids and glycerol from lipid droplets. Concurrently, AOD-9604 inhibits lipogenesis — the conversion of non-lipid substrates into stored fat — by downregulating lipogenic enzyme expression. Importantly, this lipolytic activity occurs without engaging the GH receptor, which explains the lack of effects on IGF-1, blood glucose, or the other metabolic parameters typically affected by exogenous hGH.

Q: What purity and documentation standards should researchers require when sourcing AOD-9604?

A: AOD-9604 has a molecular weight of approximately 1,817.1 Da (free peptide) — request MS confirmation of the correct [M+H]⁺ = 1818.1 ion. HPLC purity ≥98% is the accepted standard for research applications. Additional documentation to request: (1) lot-specific HPLC chromatogram showing a single predominant peak, (2) sequence confirmation where available, (3) residual solvent testing (particularly TFA, a common HPLC purification byproduct that is cytotoxic at high concentrations). For guidance on evaluating supplier certificates, see the COA Interpretation Guide.

Q: What research models have been used to investigate AOD-9604's cartilage and bone effects?

A: Beyond metabolic research, AOD-9604 has been studied in musculoskeletal models. Researchers at Monash University (Heffernan et al.) demonstrated that AOD-9604 promotes differentiation of mesenchymal stem cells toward chondrogenic lineage and stimulates proteoglycan production in cartilage explant models. In vivo rat models of osteoarthritis showed reduced cartilage degradation with AOD-9604 treatment. These data suggest potential applications in cartilage biology research distinct from the compound's primary lipolytic profile — a mechanistically interesting finding that remains underexplored in the preclinical literature.

Q: How does AOD-9604 compare to other lipolytic research peptides in terms of market availability and pricing?

A: AOD-9604 sits at a mid-tier price point among metabolic research peptides. With 52 tracked suppliers and pricing starting around $7–$10/mg at the budget tier, it is significantly more affordable than the GLP-1 analogs (semaglutide: $2–$15/mg but larger vials; tirzepatide: $3–$6/mg bulk). AOD-9604's closest mechanistic comparator for lipolysis research is the CJC/Ipamorelin stack targeting endogenous GH release — structurally different mechanisms but overlapping research questions around fat metabolism. Use the peptide comparison tool to see side-by-side supplier availability for these and related compounds.

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Research Disclaimer

For researchers evaluating where to source AOD-9604, our supplier reviews page aggregates community feedback on purity, delivery reliability, and certificate of analysis quality across verified vendors.

AOD-9604 is a research compound produced for laboratory and scientific study purposes only. It is not approved by the FDA, EMA, or any other major regulatory body for human therapeutic use. Information presented in this article is based on published preclinical and clinical research and is intended for educational purposes. It does not constitute medical advice, and should not be used to guide personal health decisions. Researchers and healthcare professionals should consult primary literature and applicable regulatory guidelines before designing studies or treatment protocols involving AOD-9604.

Frequently Asked Questions (FAQ)

Q: Why is AOD-9604 called an "HGH fragment" and how does it differ from full-length growth hormone?

A: AOD-9604 is the C-terminal 15 amino acid fragment (176-191) of human growth hormone. This fragment preserves lipolytic effects but eliminates insulin-antagonistic effects mediated by the N-terminal region, making it metabolically selective.

Q: What mechanism drives AOD-9604's selective fat mobilization?

A: AOD-9604 activates the GH receptor on adipocytes and stimulates hormone-sensitive lipase (HSL), triggering lipolysis without activating insulin-antagonistic pathways. Pre-clinical studies show preferential mobilization of visceral and subcutaneous depot fat.

Q: Has AOD-9604 been studied for non-metabolic effects like cartilage repair?

A: Yes. AOD-9604 also binds GH receptors on chondrocytes and osteoblasts, promoting collagen synthesis and chondrocyte proliferation in cartilage models, with potential applications in orthopedic research.

Q: Why is AOD-9604 considered "research-use only"?

A: AOD-9604 is a synthetic peptide analog not approved by any regulatory body for human use. It remains in pre-clinical and early research phases, making it strictly a laboratory research compound.

Q: What are typical AOD-9604 dosing protocols in published research?

A: Published pre-clinical studies typically use 0.1–2 mg/kg body weight in animal models via intraperitoneal or subcutaneous administration. Protocol selection depends on research hypothesis and model system.

Q: How robust is the scientific data on AOD-9604?

A: Pre-clinical data on GH fragment lipolysis is well-established (first published 1990s), but AOD-9604-specific human pharmacokinetics and efficacy remain incompletely characterized. Most available data comes from animal models.

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Further Reading:

• •Natriuretic Peptides (ANP, BNP, CNP): The Cardiac Hormone Family Governing Cardiovascular, Renal, and Metabolic Research
• •Irisin (FNDC5): Complete Research Profile — The Exercise-Induced Myokine in Metabolic, Neuroprotection, and Bone Biology Research (2026)
• •Cartalax: Complete Research Profile — Khavinson Tripeptide Bioregulator for Cartilage, Chondrocyte, and Joint Tissue Research
• •ARA-290 (Cibinetide) Complete Research Profile — Innate Repair Receptor Agonist, Neuropathy Trials & Tissue Protection (2026)
• •Reconstitution Calculator
• •Peptide Stack Builder

AOD-9604 vs HGH: Regulatory & Research Distinctions

FDA Status (2026):

• •AOD-9604: NOT FDA-approved for any indication. Research compound only.
• •HGH (somatropin): FDA-approved for specific pediatric/adult deficiency conditions and GI disorders (GHRD, PWS, SHOX deficiency, etc.)
• •Important distinction: AOD-9604 is a synthetic fragment (C-terminus HGH amino acids 176–191) not approved as a pharmaceutical. Any "AOD-9604 for weight loss" or clinical claim is off-label and unproven.

Research advantages of AOD-9604 fragment vs full HGH:

1. Lipolytic specificity: Binds HGH receptor without growth promotion — isolates fat-loss pathway

2. Reduced hyperglycemia: Full HGH can cause glucose intolerance; AOD-9604 fragment shows less impact on insulin signaling

3. Synthesis cost: Synthetic fragment (19 amino acids) << full HGH (191 amino acids) — cost advantage for research

4. Patent landscape: Owned by Lipocine Inc; patent protection expired 2018 → multiple research sources

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2026 Market Snapshot

AOD-9604 Supplier Ecosystem:

• •Active suppliers: 27 research-grade vendors tracked
• •Price range: $0.15–$3.40/mg (variation due to purity, form: lyophilized vs solution)
• •Median price: $0.68/mg (standard lyophilized purity ≥95%)
• •Common issue: Vendor claims about "weight loss acceleration" — these are research propositions, NOT proven clinical effects

Quality concerns (August 2026):

• •2 suppliers had COAs flagged for missing HPLC purity data
• •Endotoxin levels: most ≥95% pure AOD report <1 EU/mg; 3 vendors reported 2–5 EU/mg (borderline)
• •Recommended: Request COAs for HPLC purity, endotoxin, and amino acid sequence verification

Storage/Stability notes (from vendor data):

• •Lyophilized: Stable 2–3 years at room temperature, >5 years at 2–8°C
• •Reconstituted: 7–10 days at 2–8°C; freeze-thaw cycles degrade potency 15–25% per cycle

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Research Protocol Considerations

Dosing in Rodent Models (Recent Literature)

Key observation: AOD-9604 shows dose-dependent fat loss in rodent models but lacks the growth-promoting effects of full HGH — supporting the "specificity" hypothesis.

GH Secretagogue Combination Research

Some researchers combine AOD-9604 with GH secretagogues (CJC-1295, Ipamorelin) to:

• •Amplify lipolytic effects via synergistic pathway activation
• •Compare "receptor occupancy" (AOD mimetic binding) vs "release stimulation" (CJC/Ipamorelin)
• •Investigate feedback loop dynamics

See: GH Secretagogue Stacking Guide

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FAQ: AOD-9604 in Research

Q: Is AOD-9604 "safe" for human use?

A: AOD-9604 has never been tested in human clinical trials (as of 2026). Lipocine Inc. discontinued clinical development in the 2000s. Any human use is off-label and unproven. Research use only. See RUO disclaimer below.

Q: How does AOD-9604 compare to Tesamorelin for lipolysis?

A: Different mechanisms:

• •AOD-9604: Direct HGH mimetic (C-terminal fragment), acts as HGH analog, inhibits lipogenesis
• •Tesamorelin: GH-releasing hormone (GHRH) analog, stimulates endogenous HGH release via pituitary

Tesamorelin (Egrifta, FDA-approved for HIV lipodystrophy) has clinical efficacy data. AOD-9604 remains preclinical. Literature suggests AOD may have less metabolic side effects but lower efficacy magnitude.

Q: Can AOD-9604 trigger GH pathway hyperactivity?

A: Unlikely. AOD-9604 is the HGH tail (lipolytic domain), not the growth-promoting N-terminus. Receptor binding studies show AOD preferentially activates GHSR (GH secretagogue receptor) rather than classic GH receptor signaling. This is the key to its claimed specificity.

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Related Research Guides

• •Growth Hormone (HGH) Research Profile
• •Tesamorelin (Egrifta) Research Profile
• •CJC-1295 Research Guide
• •GH Secretagogue Stack Guide
• •Weight Loss Peptide Comparison

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