AOD-9604
Metabolic & Fat-Loss Research
PRECLINICAL SUPPORT
NOT ESTABLISHED
NOT APPROVED
What Is AOD-9604?
AOD-9604 is a synthetic 16-amino-acid peptide derived from the C-terminal region of human growth hormone (hGH). More specifically, FDA describes AOD-9604 as the 177–191 fragment of hGH with an additional tyrosine attached to the N-terminal end. It is sometimes referred to as Tyr-hGH(177–191) or the hGH fragment 176–191.
AOD-9604 was originally developed as a potential treatment for obesity. Researchers were interested in whether a small portion of the growth hormone molecule could influence fat metabolism and lipolysis without producing all of the growth-promoting effects associated with full-length growth hormone.
Important: AOD-9604 is not the same thing as human growth hormone. Although it is derived from part of the hGH molecule, its biological activity, clinical evidence, safety profile, and regulatory status must be evaluated independently.
Why Are Researchers Interested?
Research interest in AOD-9604 originally centered on whether the peptide could influence fat metabolism without activating the traditional growth-hormone pathway. Scientists have investigated areas including:
Animal studies provided some of the original enthusiasm. In obese mice, AOD-9604 was associated with increased fat oxidation and reduced body-weight gain without interacting with the hGH receptor in the same manner as full-length growth hormone.
What The Research Suggests
Preclinical Research Supports Effects on Fat Metabolism
Some of the strongest positive findings involving AOD-9604 come from animal research. A 2001 study involving obese mice found that AOD-9604 reduced body-weight gain and increased fat oxidation and markers of lipolysis. Unlike full-length growth hormone, it did not appear to interact directly with the hGH receptor or stimulate cell proliferation through that receptor.
Another mouse study found changes in fat metabolism and beta-3 adrenergic receptor expression following AOD-9604 administration. These experiments helped establish the scientific rationale for studying AOD-9604 as a possible metabolic compound.
Human Weight-Loss Results Were Much Less Convincing
The human evidence tells a different story. FDA's review found that several early studies were small, incompletely reported, or did not demonstrate statistically significant weight loss compared with placebo.
Most importantly, a larger randomized, double-blind, placebo-controlled obesity study enrolled 536 adults, with 502 randomized to AOD-9604 or placebo alongside a diet-and-exercise program. The study did not demonstrate a statistically significant difference in weight loss between AOD-9604 and placebo at its primary endpoint. The company subsequently discontinued development of AOD-9604 as an obesity treatment.
That distinction is essential when discussing AOD-9604: a biological rationale for fat metabolism is not the same as demonstrated clinical weight-loss effectiveness.
AOD-9604 Does Not Appear to Act Like Full-Length Growth Hormone
One reason researchers initially found AOD-9604 interesting was the possibility that it could retain some metabolic effects of growth hormone without producing the broader growth-promoting effects of hGH.
A 2013 publication summarizing six randomized, double-blind, placebo-controlled human studies reported that AOD-9604 did not significantly increase serum IGF-1 and did not produce the same negative effects on glucose metabolism associated with full-length growth hormone.
Cartilage Research Is Preclinical
AOD-9604 has also attracted attention in orthopedic and regenerative research. A 2015 study investigated intra-articular AOD-9604, alone and combined with hyaluronic acid, in a rabbit model of knee osteoarthritis. Researchers reported improvements in measures of cartilage degeneration in treated animals.
This is interesting laboratory research, but it is important to emphasize that it was an animal study. FDA's review found insufficient human clinical evidence to evaluate AOD-9604 for proposed osteoporosis or osteoarthritis uses.
Evidence At A Glance
Biological / Metabolic Rationale
Animal research demonstrates biological activity involving fat oxidation, lipolysis, and energy metabolism.
Human Weight-Loss Effectiveness
The major Phase 2B obesity program did not demonstrate statistically significant weight loss compared with placebo, and development for obesity was discontinued.
Growth Hormone / IGF-1 Effects
Published human safety data reported no meaningful increase in IGF-1 and did not demonstrate the glucose-metabolism effects associated with full-length growth hormone.
Injectable Weight-Loss Benefits
FDA did not identify adequate human evidence establishing the safety and effectiveness of subcutaneous AOD-9604 for obesity.
Cartilage / Joint Benefits
Positive findings have been reported in a rabbit osteoarthritis model, but human therapeutic effectiveness has not been established.
Safety & Limitations
Earlier human studies reported generally favorable short-term tolerability. A 2013 paper summarizing six randomized, placebo-controlled trials reported no AOD-9604-related serious adverse event or withdrawal and found no anti-AOD-9604 antibodies in the patients who underwent antibody testing.
However, FDA's later and more comprehensive regulatory review identified substantial limitations in the available safety data. FDA noted that AOD-9604 is a peptide capable of presenting immunogenicity, aggregation, impurity, and product-characterization concerns, particularly when compounded.
FDA also identified serious adverse events reported in human studies, including diarrhea, chest tightness, and various cancers, while emphasizing that causality was unclear and the available information was insufficient to determine whether those events were caused by AOD-9604.
This distinction matters: limited evidence of harm is not the same thing as evidence that a treatment is safe. FDA states that available safety information is insufficient to determine whether compounded AOD-9604 would cause harm when administered to humans.
Regulatory Status
AOD-9604 is not FDA-approved for obesity, weight loss, body composition, joint repair, anti-aging, or any other therapeutic indication. FDA evaluated AOD-9604 free base and AOD-9604 acetate in connection with the Section 503A bulk-drug-substance process.
What About Compounding?
AOD-9604 had previously been nominated for FDA's 503A bulk-drug-substance process, but those nominations were withdrawn. FDA nevertheless proceeded with an evaluation of the substances.
In December 2024, FDA's Pharmacy Compounding Advisory Committee considered AOD-9604 free base and AOD-9604 acetate together. FDA's current safety information also lists AOD-9604 among bulk drug substances whose nominations were withdrawn and identifies potential significant safety concerns associated with compounded AOD-9604.
Regulatory Status: Not FDA-Approved — AOD-9604 is not FDA-approved for weight loss or any other therapeutic indication. FDA has identified potential safety concerns involving compounded AOD-9604, and its regulatory and compounding status should be evaluated under current federal and state requirements.
AOD-9604 vs. Human Growth Hormone
AOD-9604 was specifically investigated because researchers hoped to separate certain metabolic properties associated with hGH from its broader growth-promoting activity. Research involving one should not be presented as evidence for the other.
AOD-9604
A synthetic 16-amino-acid peptide based on the C-terminal region of human growth hormone, investigated for effects on fat metabolism and lipolysis without the broader growth-promoting activity of full-length hGH.
Human Growth Hormone (hGH)
A 191-amino-acid hormone produced naturally by the pituitary gland that affects growth, metabolism, IGF-1 signaling, and numerous tissues throughout the body.
Why the Difference Matters: Research involving full-length human growth hormone should not be presented as evidence that AOD-9604 produces the same effects, and research involving AOD-9604 should not be used to imply that it carries all of the established clinical effects of hGH.
Research & Publications
FDA Evaluation — AOD-9604-Related Bulk Drug Substances
U.S. Food and Drug Administration — 2024
FDA's detailed scientific review of AOD-9604 free base and AOD-9604 acetate, including identity, human studies, effectiveness, safety, immunogenicity, manufacturing concerns, and regulatory considerations.
View FDA AOD-9604 EvaluationFDA Pharmacy Compounding Advisory Committee — Final Minutes
U.S. Food and Drug Administration — 2024/2025
Official FDA meeting record documenting the committee's consideration of AOD-9604 and its vote against inclusion of AOD-9604 free base and acetate on the 503A Bulks List.
View FDA Final Summary MinutesSafety and Tolerability of AOD-9604 in Humans
Journal of Endocrinology and Metabolism — 2013
Summarizes safety information from six randomized, double-blind, placebo-controlled human studies and examines IGF-1, glucose metabolism, adverse events, and antibody formation.
View Human AOD-9604 StudyAOD-9604, Fat Oxidation and Weight in Obese Mice
International Journal of Obesity — 2001
A preclinical study examining body weight, fat oxidation, lipolysis, glucose metabolism, and growth-hormone receptor activity in obese mice.
View on PubMedAOD-9604 and Lipid Metabolism
Endocrinology — 2001
Animal research examining AOD-9604, lipid metabolism, lipolysis, and beta-3 adrenergic pathways.
View on PubMedAOD-9604 in a Rabbit Osteoarthritis Model
Preclinical Animal Research — 2015
A preclinical study examining intra-articular AOD-9604, alone and with hyaluronic acid, in rabbits with experimentally induced knee osteoarthritis.
View on PubMedFDA — Potential Safety Risks With Compounded AOD-9604
U.S. Food and Drug Administration
FDA's current information concerning peptide impurities, immunogenicity, active pharmaceutical ingredient characterization, limited human safety information, and reported adverse events associated with AOD-9604.
View FDA Safety ResourceAOD-9604 is an investigational peptide with an established history of scientific research, but biological activity should not be confused with established treatment effectiveness.
Positive findings from animal studies involving fat metabolism, cartilage, or other biological effects should be evaluated separately from evidence in humans.
Current human evidence has not established AOD-9604 as an effective weight-loss treatment, and evidence supporting commonly marketed subcutaneous AOD-9604 injections remains limited.
This page is provided for educational purposes only. AOD-9604 is not offered for sale, prescription, or distribution through this website.