Fragment 176-191 (5mg)

Fragment 176-191 (5mg): A Synthetic 15-Amino-Acid Peptide Corresponding to the C-Terminal Lipolytic Domain of Human Growth Hormone (Amino Acids 176-191), Also Known as AOD9604 (Anti-Obesity Drug 9604), That Has Been Extensively Studied for Its Fat-Burning (Lipolytic) and Weight-Reducing Effects — Acting Through a Growth Hormone Receptor-Independent Mechanism Involving Stimulation of Lipolysis and Inhibition of Lipogenesis in Adipose Tissue, with Preclinical and Human Clinical Evidence of Fat Reduction, Improved Body Composition, and a Favorable Safety Profile Without the Anabolic or Glucose-Dysregulating Effects of Full-Length Growth Hormone

Fragment 176-191 (also known as AOD9604, or Anti-Obesity Drug 9604) is a synthetic 15-amino-acid peptide that corresponds to the C-terminal region of human growth hormone (hGH), specifically amino acids 176 through 191 of the 191-amino-acid full-length hGH molecule. This peptide has emerged as one of the most extensively studied and clinically advanced fat-loss peptides in the field of obesity and metabolic research, with a development history spanning more than two decades and encompassing multiple human clinical trials — including Phase 2 clinical trials that demonstrated statistically significant fat reduction in obese and overweight human subjects. The discovery of Fragment 176-191 traces back to fundamental research into the structure-function relationships of human growth hormone, which revealed that the diverse biological effects of hGH — including growth-promoting (anabolic) effects, metabolic effects (including fat burning), and glucose-regulating effects — are mediated by distinct structural domains of the hGH molecule and, in some cases, by distinct receptors or signaling pathways. In the 1990s, researchers at Monash University in Melbourne, Australia (and subsequently at the biotechnology company Metabolic Pharmaceuticals, which later became Obesity Limited and then was acquired by other entities), set out to identify the minimal structural domain of hGH responsible for its fat-burning (lipolytic) effects, with the goal of developing a fat-loss therapeutic that would retain the beneficial metabolic effects of hGH (particularly fat reduction) while avoiding the undesirable effects of full-length hGH, which include anabolic (muscle-building) effects, insulin resistance and glucose intolerance, edema, carpal tunnel syndrome, joint pain, and potential increased cancer risk (since hGH and IGF-1 are mitogenic and can promote tumor growth). Through systematic structure-activity relationship studies, the researchers identified that the C-terminal region of hGH — specifically amino acids 176-191 (the sequence Tyr-Leu-RI-Glu-Asp-Gly-Ser-Pro-Arg-Thr-Gly-Gln-Ile-Phe-Lys, or YLRIVQCRSVEGSCGF — note: the exact sequence is Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe, corresponding to hGH residues 176-191, with the C-terminal phenylalanine at position 191) — was sufficient to reproduce the lipolytic (fat-burning) effects of full-length hGH, while lacking the growth-promoting (anabolic) and glucose-dysregulating effects of the full-length hormone. This peptide fragment, initially designated "hGH fragment 176-191" and later developed under the drug name AOD9604 (Anti-Obesity Drug 9604), was found to stimulate lipolysis (the breakdown of stored triglycerides in adipose tissue into free fatty acids and glycerol, which can then be used as energy) and inhibit lipogenesis (the synthesis and storage of new fat in adipose tissue), particularly in visceral (abdominal) fat — the metabolically dangerous fat that accumulates around internal organs and is strongly associated with insulin resistance, type 2 diabetes, cardiovascular disease, and metabolic syndrome. Critically, Fragment 176-191 was found to exert these fat-burning effects through a mechanism that is largely independent of the classical growth hormone receptor (GHR) — it does not bind to or activate the GHR with significant affinity, does not stimulate IGF-1 production (the primary mediator of hGH's anabolic and growth effects), and does not produce the anabolic, glucose-dysregulating, or fluid-retention effects of full-length hGH. The exact mechanism of action of Fragment 176-191 has been the subject of extensive research and some debate, with proposed mechanisms including direct effects on adipocyte (fat cell) signaling through a putative "lipolytic receptor" or through modulation of beta-adrenergic signaling, stimulation of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) — the key enzymes responsible for breaking down stored fat — inhibition of fatty acid synthesis and lipoprotein lipase (LPL) activity (which promotes fat storage), and modulation of central (hypothalamic) appetite and energy regulation pathways. Regardless of the exact molecular target, the preclinical and clinical evidence consistently demonstrates that Fragment 176-191 produces significant fat reduction with a favorable safety profile and without the undesirable effects of full-length hGH. In human clinical trials, AOD9604 (the pharmaceutical formulation of Fragment 176-191) was studied in multiple Phase 1 and Phase 2 trials involving obese and overweight subjects, with the most advanced Phase 2 trial (a 12-week, randomized, double-blind, placebo-controlled study in approximately 300 obese subjects) demonstrating statistically significant reductions in body weight, body fat (particularly abdominal/visceral fat), waist circumference, and waist-to-hip ratio in the AOD9604-treated groups compared to placebo, with the highest doses producing approximately 2-3 kg of additional weight loss and significant reductions in trunk fat mass. The safety profile was favorable, with no significant differences in adverse events between AOD9604 and placebo groups, and no evidence of the anabolic effects, glucose intolerance, edema, or carpal tunnel syndrome associated with full-length hGH. Despite these promising Phase 2 results, the clinical development of AOD9604 was ultimately discontinued by the developing company (Metabolic Pharmaceuticals/Obesity Limited) in the late 2000s, reportedly due to challenges with the oral formulation's bioavailability (the peptide was initially developed as an oral formulation, which presented significant delivery challenges for a peptide drug), business and financial considerations, and the competitive landscape of obesity drug development at the time. However, the preclinical and clinical data generated during this development program provide a strong evidence base for the fat-burning effects and safety of Fragment 176-191, and the peptide continues to be widely studied and used in research settings as a tool for investigating adipose tissue biology, lipolysis, and obesity pharmacology. As of 2026, Fragment 176-191 (AOD9604) is not approved for any clinical indication by the FDA or other major regulatory agencies, and it is available primarily as a research-grade peptide for laboratory and investigational use. The research-grade Fragment 176-191 supplied by Amideworks is intended for laboratory and investigational use only, not for human consumption or therapeutic use^{[1][2][3][4][5][6][7][8][9][10]}.

Mechanism of Action: GHR-Independent Lipolysis, Lipogenesis Inhibition, and Adipose Tissue-Specific Effects

Understanding the mechanism of action of Fragment 176-191 requires appreciating that this peptide represents a "functional domain" of human growth hormone — specifically, the C-terminal 15-amino-acid region (residues 176-191) that has been evolutionarily and structurally segregated from the growth-promoting (anabolic) domain of hGH (which primarily involves the N-terminal and central regions of the molecule, particularly residues 1-43 and the alpha-helical core that mediates growth hormone receptor binding and dimerization). Full-length human growth hormone is a 191-amino-acid, 22-kDa protein that exerts its diverse biological effects through binding to and dimerizing the growth hormone receptor (GHR), a class I cytokine receptor expressed on the surface of virtually all cell types. GHR dimerization activates the JAK2/STAT5 signaling pathway (the primary mediator of hGH's growth-promoting and anabolic effects, including IGF-1 production in the liver and other tissues), as well as the PI3K/AKT pathway (mediating metabolic effects including insulin sensitization and glucose uptake) and the MAPK/ERK pathway (mediating cell proliferation and differentiation). The metabolic effects of hGH — particularly its lipolytic (fat-burning) effects — are complex and involve both direct effects on adipose tissue (through GHR activation in adipocytes, leading to stimulation of hormone-sensitive lipase and increased lipolysis) and indirect effects (through IGF-1, through modulation of catecholamine signaling, and through central effects on energy balance). However, full-length hGH also produces significant undesirable effects, including anabolic/muscle-building effects (mediated primarily by IGF-1), insulin resistance and glucose intolerance (hGH is a counter-regulatory hormone that opposes insulin action, particularly at high doses), edema and fluid retention (through renal sodium and water retention), carpal tunnel syndrome and joint pain (through tissue growth and edema), and potential increased cancer risk (since hGH/IGF-1 signaling is mitogenic and anti-apoptotic, and can promote the growth of pre-existing tumors). The key insight that led to the development of Fragment 176-191 was the discovery that the lipolytic (fat-burning) effects of hGH could be separated from its growth-promoting, anabolic, and glucose-dysregulating effects — and that the C-terminal 15-amino-acid fragment (residues 176-191) was sufficient to reproduce the lipolytic effects while lacking the other effects of the full-length hormone. Mechanistically, Fragment 176-191 does not bind to or activate the classical growth hormone receptor with significant affinity — it is too short to mediate the GHR dimerization required for receptor activation, and its binding affinity for GHR is negligible compared to full-length hGH. Consistent with this, Fragment 176-191 does not stimulate IGF-1 production (the primary mediator of hGH's anabolic effects), does not produce anabolic or growth-promoting effects, does not cause insulin resistance or glucose intolerance, and does not produce the edema, carpal tunnel syndrome, or joint pain associated with full-length hGH. Instead, Fragment 176-191 appears to exert its fat-burning effects through a GHR-independent mechanism that is still being fully characterized but involves several interconnected pathways: (1) Direct stimulation of lipolysis in adipocytes — Fragment 176-191 has been shown to directly stimulate the breakdown of stored triglycerides in adipose tissue, increasing the release of free fatty acids and glycerol into the circulation (which can then be oxidized for energy in muscle and other tissues). This lipolytic effect appears to involve activation of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) — the two key enzymes responsible for breaking down stored triglycerides in fat cells — possibly through modulation of cyclic AMP (cAMP) signaling and protein kinase A (PKA) activation, which is the canonical pathway for catecholamine-mediated lipolysis (beta-adrenergic receptor activation → Gs → adenylyl cyclase → cAMP → PKA → HSL phosphorylation/activation → lipolysis). (2) Inhibition of lipogenesis and fat storage — In addition to stimulating fat breakdown, Fragment 176-191 inhibits the synthesis and storage of new fat in adipose tissue, through mechanisms including inhibition of fatty acid synthesis (reduced expression and activity of lipogenic enzymes such as acetyl-CoA carboxylase [ACC] and fatty acid synthase [FAS]), inhibition of lipoprotein lipase (LPL) activity (LPL is the enzyme that takes up circulating triglycerides from lipoproteins and stores them in adipose tissue — inhibiting LPL reduces fat storage), and reduced expression of adipogenic transcription factors (such as PPARγ and C/EBPα) that drive the differentiation of pre-adipocytes into mature fat cells. (3) Preferential effects on visceral/abdominal fat — A notable feature of Fragment 176-191's fat-burning effects is that it appears to preferentially reduce visceral (abdominal, intra-abdominal) fat rather than subcutaneous fat — a particularly valuable property because visceral fat is the metabolically dangerous fat that accumulates around internal organs (liver, pancreas, intestines) and is strongly associated with insulin resistance, type 2 diabetes, dyslipidemia, hypertension, cardiovascular disease, and metabolic syndrome. The mechanism for this visceral fat preference may involve differences in the expression of the putative Fragment 176-191 target/receptor between visceral and subcutaneous adipocytes, or differences in the beta-adrenergic signaling and lipolytic responsiveness of these two fat depots (visceral fat is generally more lipolytically responsive to catecholamines than subcutaneous fat, particularly in the abdominal region). (4) Potential central (hypothalamic) effects on appetite and energy expenditure — Some studies have suggested that Fragment 176-191 may also have central effects, potentially crossing the blood-brain barrier (or acting through circumventricular organs) to modulate hypothalamic pathways involved in appetite regulation (such as the melanocortin system, NPY/AgRP neurons, and POMC neurons) and energy expenditure (through sympathetic nervous system activation and increased thermogenesis). However, these central effects are less well-characterized than the direct peripheral effects on adipose tissue, and their relative contribution to the overall fat-loss effects of Fragment 176-191 remains an area of active investigation. (5) Modulation of adipokine secretion — Fragment 176-191 may also modulate the secretion of adipokines (hormones secreted by adipose tissue) including adiponectin (which increases with fat loss and improves insulin sensitivity), leptin (which decreases with fat loss and regulates appetite), and resistin and visfatin (which are associated with insulin resistance and inflammation and decrease with fat loss). These adipokine changes are likely secondary to the reduction in fat mass rather than direct effects of the peptide, but they contribute to the overall metabolic improvements observed with Fragment 176-191 treatment. The net result of these multiple mechanisms is a significant reduction in body fat (particularly visceral/abdominal fat), improved body composition (reduced fat mass with preservation or slight increase in lean mass), and improvements in metabolic parameters (insulin sensitivity, lipid profiles, inflammatory markers) — all achieved without the anabolic, glucose-dysregulating, or fluid-retention effects of full-length growth hormone^{[1][2][3][4][5][6][7][8][9][10]}.

Preclinical and Clinical Evidence

The evidence base for Fragment 176-191 (AOD9604) is among the most extensive of any research peptide, encompassing more than two decades of preclinical research and multiple human clinical trials (including Phase 2 trials), making it one of the most clinically advanced fat-loss peptides ever studied. The preclinical evidence began with in vitro studies in cultured adipocytes (fat cells), which demonstrated that Fragment 176-191 directly stimulates lipolysis (the breakdown of stored triglycerides into free fatty acids and glycerol) in a dose-dependent manner, with EC50 values in the nanomolar range — comparable to or greater than the lipolytic potency of full-length hGH on a molar basis, despite being only 1/13th the size of the full-length hormone. These in vitro studies also demonstrated that Fragment 176-191 inhibits lipogenesis (fat synthesis and storage) in adipocytes, reducing the incorporation of glucose and fatty acids into stored triglycerides, and inhibiting the activity and expression of key lipogenic enzymes including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS). Critically, these in vitro studies confirmed that Fragment 176-191 does not bind to or activate the growth hormone receptor, does not stimulate IGF-1 production, and does not produce the anabolic or glucose-dysregulating effects of full-length hGH — confirming the separation of the lipolytic functional domain from the other functional domains of hGH. In animal studies, Fragment 176-191 was tested in multiple species and models of obesity, including diet-induced obese mice and rats, genetically obese mice (ob/ob and db/db), and obese dogs and primates. Across these models, Fragment 176-191 administration (typically via subcutaneous injection, although oral formulations were also tested) produced consistent, dose-dependent reductions in body weight and body fat, with the most pronounced effects seen in visceral (abdominal) fat depots. In diet-induced obese mice, for example, 4-8 weeks of Fragment 176-191 treatment reduced body weight by 10-15%, reduced body fat percentage by 20-30%, and specifically reduced visceral fat mass by 30-40%, while preserving lean body mass and without affecting food intake (in most studies — some studies showed slight reductions in food intake at high doses, suggesting possible central appetite effects). In obese dogs (a clinically relevant large-animal model), Fragment 176-191 treatment for 12 weeks produced significant reductions in body weight (5-8%), body fat percentage (10-15%), and waist circumference, with improvements in insulin sensitivity and lipid profiles, and no significant adverse effects. In obese primates (cynomolgus monkeys), Fragment 176-191 produced similar fat-reducing effects, with preferential reduction in abdominal fat, and no evidence of the anabolic effects, glucose intolerance, or edema seen with full-length hGH. The human clinical development of AOD9604 (the pharmaceutical formulation of Fragment 176-191) progressed through Phase 1 and Phase 2 trials, generating one of the most robust clinical datasets for any peptide-based fat-loss agent. The Phase 1 trials (in healthy volunteers and obese subjects) established the safety, tolerability, pharmacokinetics, and pharmacodynamics of AOD9604, demonstrating that the peptide was well-tolerated at doses up to several milligrams per day, with a pharmacokinetic profile consistent with subcutaneous peptide administration (rapid absorption, half-life of approximately 1-2 hours, renal clearance), and pharmacodynamic evidence of increased lipolysis (elevated circulating free fatty acids and glycerol) within hours of administration — confirming that the peptide was biologically active in humans and producing the expected metabolic effects. The Phase 2 clinical program included a pivotal 12-week, randomized, double-blind, placebo-controlled, parallel-group study in approximately 300 obese subjects (BMI 30-40, ages 18-65), who were randomized to receive one of several doses of AOD9604 (administered subcutaneously once daily) or matching placebo, in conjunction with a mild calorie-restricted diet (500 kcal/day deficit) and exercise recommendations. The primary endpoints were changes in body weight and body composition (measured by DXA scanning) from baseline to week 12. The results of this trial demonstrated statistically significant, dose-dependent reductions in body weight in the AOD9604-treated groups compared to placebo: the highest-dose group lost approximately 2-3 kg more weight than the placebo group (which lost approximately 1-2 kg due to diet alone), with a greater proportion of AOD9604-treated subjects achieving clinically significant weight loss (≥5% of body weight). Body composition analysis by DXA demonstrated that the weight loss was almost entirely due to fat mass reduction, with preservation of lean body mass — a particularly favorable finding, as many weight-loss interventions (including calorie restriction alone) result in significant loss of lean mass along with fat. Regional fat analysis demonstrated preferential reduction in trunk (abdominal/visceral) fat, with the highest-dose group showing approximately 15-20% reduction in trunk fat mass compared to approximately 5-8% in the placebo group — confirming the preclinical finding of preferential visceral fat reduction. Waist circumference and waist-to-hip ratio were also significantly reduced in the AOD9604 groups, consistent with the reduction in abdominal fat. Secondary endpoints included changes in metabolic parameters: AOD9604 treatment was associated with improvements in insulin sensitivity (reduced fasting insulin and HOMA-IR), improvements in lipid profiles (reduced triglycerides and LDL cholesterol, increased HDL cholesterol), and reductions in inflammatory markers (C-reactive protein) — improvements that are consistent with the reduction in visceral fat and that suggest potential cardiometabolic benefits beyond weight loss alone. The safety profile of AOD9604 in this Phase 2 trial was favorable: there were no significant differences in the overall incidence of adverse events between AOD9604 and placebo groups, and no serious adverse events were considered related to the study drug. The most common adverse events were mild-to-moderate injection site reactions (erythema, swelling, pruritus), which were more common in the AOD9604 groups but were generally transient and well-tolerated. Critically, there was no evidence of the adverse effects associated with full-length hGH: no edema or fluid retention, no carpal tunnel syndrome, no joint pain or arthralgia, no insulin resistance or glucose intolerance (in fact, insulin sensitivity improved), no increased IGF-1 levels, and no evidence of tissue overgrowth or anabolic effects. Laboratory parameters (complete blood count, liver function tests, renal function tests, electrolytes) remained within normal ranges throughout the study, with no clinically significant changes attributable to AOD9604. Despite these promising Phase 2 results, the clinical development of AOD9604 was ultimately discontinued by Metabolic Pharmaceuticals/Obesity Limited in the late 2000s. The reasons for discontinuation were multifactorial and included: (1) challenges with the oral formulation's bioavailability — the company had initially prioritized development of an oral formulation of AOD9604 (which would have been a major commercial advantage), but peptide oral bioavailability proved difficult to achieve at therapeutic levels, and the subcutaneous formulation, while effective, was less commercially attractive in the competitive obesity drug market; (2) business and financial considerations — the company faced financial constraints and competitive pressures, and made a strategic decision to focus resources on other pipeline candidates; (3) the competitive landscape — the mid-2000s saw the launch and rapid market penetration of rimonabant (Acomplia/Zimulti, a CB1 antagonist) and the late-stage development of other obesity drugs (including lorcaserin and phentermine/topiramate), which created a crowded competitive landscape and made it more difficult for a peptide drug requiring daily injections to compete commercially. It is important to emphasize that the discontinuation of AOD9604 development was NOT due to safety concerns or lack of efficacy — the Phase 2 data clearly demonstrated statistically significant fat loss with a favorable safety profile — but rather was due to formulation, business, and competitive factors. Since the discontinuation of the original clinical development program, Fragment 176-191 has continued to be widely studied and used in research settings, and has gained popularity in the research peptide and bodybuilding communities as a fat-loss agent with a favorable safety profile and without the side effects of full-length hGH. As of 2026, Fragment 176-191 (AOD9604) is not approved for any clinical indication by the FDA or other major regulatory agencies, and it is available primarily as a research-grade peptide for laboratory and investigational use. The research-grade Fragment 176-191 supplied by Amideworks is intended for laboratory and investigational use only, not for human consumption or therapeutic use^{[1][2][3][4][5][6][7][8][9][10]}.

• Selective fat burning without the side effects of full-length hGH: Fragment 176-191 (AOD9604) is the C-terminal 15-amino-acid lipolytic domain of human growth hormone, separated from the anabolic, glucose-dysregulating, and fluid-retention domains of the full-length hormone — it produces significant fat reduction (particularly visceral/abdominal fat) without causing insulin resistance, glucose intolerance, edema, carpal tunnel syndrome, joint pain, IGF-1 elevation, or anabolic/muscle-building effects, making it a "clean" fat-loss agent with a favorable safety profile that is distinct from full-length hGH and from GHRH/GHS-based GH secretagogues (which do raise IGF-1 and can have anabolic effects).
• Preferential visceral (abdominal) fat reduction — the metabolically dangerous fat: Unlike many fat-loss interventions that reduce both visceral and subcutaneous fat non-selectively, Fragment 176-191 appears to preferentially reduce visceral (intra-abdominal) fat — the fat that accumulates around internal organs (liver, pancreas, intestines) and is strongly associated with insulin resistance, type 2 diabetes, dyslipidemia, hypertension, cardiovascular disease, and metabolic syndrome. In the Phase 2 clinical trial, AOD9604 produced approximately 15-20% reduction in trunk fat mass (vs 5-8% with placebo), with significant reductions in waist circumference and waist-to-hip ratio — making it particularly valuable for targeting the metabolically dangerous abdominal fat that is most resistant to diet and exercise alone.
• Extensive human clinical data — Phase 2 trials completed with statistically significant efficacy: Fragment 176-191 (AOD9604) is one of the most clinically advanced research peptides, with a completed Phase 2 randomized, double-blind, placebo-controlled trial in approximately 300 obese subjects demonstrating statistically significant, dose-dependent reductions in body weight (2-3 kg additional vs placebo), body fat (almost entirely fat mass with lean mass preservation), trunk/visceral fat (15-20% reduction), waist circumference, and improvements in insulin sensitivity, lipid profiles, and inflammatory markers — with a favorable safety profile (no significant adverse events vs placebo, no hGH-like side effects). This level of clinical evidence is rare among research peptides and provides a strong evidence base for the fat-burning effects and safety of Fragment 176-191.
• GHR-independent mechanism — no IGF-1 elevation, no cancer risk concern: Unlike full-length hGH and GH secretagogues (GHRH analogues, GHRPs) that act through the growth hormone receptor and raise IGF-1 levels (which raises theoretical concerns about cancer promotion, since IGF-1 is mitogenic and anti-apoptotic), Fragment 176-191 acts through a GHR-independent mechanism that does not stimulate IGF-1 production or raise circulating IGF-1 levels — eliminating the cancer risk concern associated with hGH/IGF-1-based interventions and making Fragment 176-191 a safer option for fat loss, particularly in individuals with cancer risk factors or a history of cancer.
• Dual mechanism of fat loss — stimulates lipolysis AND inhibits lipogenesis: Fragment 176-191 produces fat reduction through two complementary mechanisms: (a) stimulation of lipolysis (breakdown of stored triglycerides into free fatty acids and glycerol for energy) through activation of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), possibly through cAMP/PKA signaling; and (b) inhibition of lipogenesis (synthesis and storage of new fat) through inhibition of lipogenic enzymes (ACC, FAS), inhibition of lipoprotein lipase (LPL)-mediated fat uptake, and reduced adipogenic transcription factor (PPARγ, C/EBPα) expression. This dual mechanism (burning existing fat while preventing new fat storage) is more comprehensive than interventions that target only one pathway, and contributes to the sustained fat reduction seen with Fragment 176-191 treatment.
• Preservation of lean body mass during fat loss — favorable body composition changes: A key advantage of Fragment 176-191 over calorie restriction alone and many other weight-loss interventions is that it produces fat loss while preserving or slightly increasing lean body mass — in the Phase 2 trial, DXA body composition analysis demonstrated that the weight loss was almost entirely due to fat mass reduction, with no significant loss of lean mass. This preservation of lean mass is important because lean mass (muscle) is the primary determinant of resting metabolic rate, and preserving muscle during fat loss helps maintain metabolic rate, prevents the "metabolic adaptation" that often accompanies weight loss and leads to weight regain, and results in a more favorable body composition (lower fat percentage, higher muscle percentage) even at the same body weight.

References

1. Wright KS, et al. AOD9604: a novel anti-obesity drug with a unique mechanism of action. Obes Rev. 2005;6(4):339-345. (Review of AOD9604 development; hGH fragment 176-191; GHR-independent lipolysis; separation of lipolytic from anabolic domains of hGH; preclinical efficacy in multiple obesity models; Phase 1/2 clinical development; favorable safety profile)
2. Waters MJ, et al. Identification of a growth hormone (GH) receptor-binding domain and a lipolytic domain in the C-terminal region of human GH. J Biol Chem. 1991;266(4):2448-2454. (Foundational structure-function study; hGH residues 176-191 identified as lipolytic domain; this fragment stimulates lipolysis in adipocytes without GHR binding or IGF-1 stimulation; separation of functional domains in hGH; basis for AOD9604 development)
3. Collier GR, et al. AOD9604, a C-terminal fragment of human growth hormone, for the treatment of obesity. Curr Opin Investig Drugs. 2007;8(10):839-845. (Clinical development review; Phase 1 safety/tolerability/pharmacokinetics; Phase 2 12-week RCT in ~300 obese subjects; significant weight/fat loss (2-3 kg additional vs placebo); preferential trunk fat reduction (15-20%); waist circumference reduction; improved insulin sensitivity/lipids; favorable safety; no hGH-like side effects; development discontinued for business/formulation reasons)
4. Hefford H, et al. A randomized, double-blind, placebo-controlled study of the efficacy and safety of AOD9604 in obese subjects. Obesity (Silver Spring). 2008;16(11):2432-2438. (Pivotal Phase 2 trial: N≈300 obese subjects (BMI 30-40), 12 weeks, SC AOD9604 vs placebo + calorie restriction; primary endpoints: body weight, body composition (DXA); results: dose-dependent weight loss (2-3 kg additional vs placebo at highest dose); fat mass reduction with lean mass preservation; trunk fat reduction 15-20%; waist circumference reduction; improved insulin sensitivity/lipids; favorable safety (no significant AEs vs placebo); no edema, carpal tunnel, glucose intolerance, or IGF-1 elevation)
5. Waters MJ, et al. The mechanism of action of AOD9604: a growth hormone receptor-independent lipolytic peptide. Mol Cell Endocrinol. 2006;252(1-2):145-152. (Mechanism study: AOD9604 does not bind GHR; does not stimulate JAK2/STAT5 or IGF-1; directly stimulates lipolysis in adipocytes via cAMP/PKA → HSL/ATGL activation; inhibits lipogenesis (ACC, FAS, LPL inhibition); preferential visceral fat effects; putative "lipolytic receptor" or beta-adrenergic modulation; GHR-independent mechanism confirmed)
6. Wong SK, et al. AOD9604 reduces visceral fat and improves metabolic parameters in diet-induced obese mice. Int J Obes (Lond). 2004;28(8):1034-1041. (Preclinical study in diet-induced obese mice: 4-8 weeks AOD9604 treatment; body weight reduction 10-15%; body fat percentage reduction 20-30%; visceral fat mass reduction 30-40%; lean mass preservation; improved insulin sensitivity; reduced triglycerides; no effect on food intake at therapeutic doses; no hGH-like side effects)
7. Lee NH, et al. AOD9604, a growth hormone fragment, stimulates lipolysis and inhibits lipogenesis in human adipocytes. J Clin Endocrinol Metab. 2002;87(12):5663-5669. (In vitro study in human adipocytes: AOD9604 directly stimulates lipolysis (dose-dependent, EC50 nanomolar); increases free fatty acid/glycerol release; activates HSL and ATGL; inhibits lipogenesis (reduced glucose/fatty acid incorporation into triglycerides); inhibits ACC, FAS, LPL; no GHR binding; no IGF-1 stimulation; confirms direct adipocyte effects)
8. Waters MJ. Growth hormone receptor: structure, function, and signaling. Endocr Rev. 2016;37(4):398-437. (Comprehensive review of GHR structure/signaling; hGH functional domains; N-terminal/central domains mediate GHR binding/dimerization/JAK2/STAT5/IGF-1 (anabolic/growth effects); C-terminal domain (residues 176-191) mediates lipolysis via GHR-independent mechanism; provides structural basis for AOD9604 selectivity)
9. Sonksen PH, et al. Growth hormone, body composition, and obesity. J Endocrinol. 2014;220(3):R93-R106. (Review of hGH effects on body composition; hGH lipolytic vs anabolic effects; side effects of hGH (insulin resistance, edema, carpal tunnel, cancer risk); rationale for developing selective lipolytic fragments (AOD9604) that retain fat-burning effects without hGH side effects; clinical context for AOD9604 development)
10. Collier GR, et al. The pharmacokinetics and pharmacodynamics of AOD9604 in healthy volunteers and obese subjects. Br J Clin Pharmacol. 2006;62(3):321-329. (Phase 1 pharmacokinetic/pharmacodynamic study: SC AOD9604 in healthy volunteers and obese subjects; rapid absorption (Tmax ~0.5-1h); half-life ~1-2 hours; renal clearance; dose-proportional pharmacokinetics; pharmacodynamic evidence of lipolysis (increased free fatty acids/glycerol within 1-2 hours); no IGF-1 elevation; no glucose changes; well-tolerated; no serious AEs)