AOD-9604: a growth hormone fragment whose obesity trials were never published

AOD-9604 is the "fat-burning fragment" of growth hormone. It is also a cautionary tale about the difference between a compound that has been in human trials and a compound whose human trials you can read.

What it is

Human growth hormone is 191 amino acids long. Work at Monash University in the 1990s identified the C-terminal region, residues 177 to 191, as the part responsible for the hormone's effect on fat metabolism (PubMed 11116208). AOD-9604 is that fragment with a tyrosine added at the N-terminus for stability. The intended advantage was lipolysis without the growth-promoting and glucose-raising effects of the whole hormone. Metabolic Pharmaceuticals of Melbourne developed it.

The evidence

Animal and in vitro. Oral AOD-9401, a closely related fragment, reduced weight gain in obese mice and stimulated lipolysis in isolated human fat cells (PubMed 10950816). Further rodent work followed.

Human. A 2004 pipeline review (PubMed 15134286) records phase 2a obesity trials under way by February 2002. The company later reported phase 2b results by announcement; the obesity programme was then discontinued. We searched PubMed on September 4, 2026 for any human interventional study of AOD-9604 and found none. What exists in the indexed literature is reviews that mention the programme.

That gap is the finding. A trial that has been run but not published cannot be examined for its design, its endpoints, its dropout rate or its adverse events. Sales pages that say AOD-9604 "has been through six human trials" are referring to studies nobody outside the sponsor has read.

Regulatory status

FDA placed AOD-9604 in Category 2 on September 29, 2023. The Category 2 page (content current as of April 22, 2026) lists it as nominated but withdrawn and keeps the concern in full: significant risk of immunogenicity for certain routes, complexities with impurities and characterisation, no or only limited safety-related information, and "FDA has also identified serious adverse events that may be associated with AOD-9604, though causality is not clear."

The Pharmacy Compounding Advisory Committee considered AOD-9604 in December 2024. It is not on the 503A bulks list, not in Category 1, and not an ingredient of any FDA-approved drug. The 503A explainer covers the process.

Safety signals

FDA's statement that it has identified serious adverse events possibly associated with AOD-9604 is the only regulator-level safety statement for any Category 2 peptide on this site apart from ipamorelin and CJC-1295. FDA did not publish the details, and "causality is not clear" is doing real work in that sentence. It remains the case that a body has looked at adverse event reports and chosen to say so.

Grade: D + X

D because there is no published controlled human trial; the sponsor's unpublished programme is noted and excluded. X for FDA's published safety concern. If the interest is weight loss, the peptides with published phase 3 trials and approved labels are the GLP-1 agonists.