Retatrutide + AOD-9604
One of these failed its pivotal trial in 2007 and was abandoned.
Retatrutide is the most effective weight loss compound ever tested. AOD-9604 went through a 536-person trial over 24 weeks. It missed its primary endpoint, the single result a trial is designed to prove, at every dose. The company terminated development three months later. The detailed results were never published.
Appetite from one side, fat cells from the other.
Retatrutide works by suppressing appetite and changing how the body handles energy. AOD-9604 is meant to work further down the chain, acting on fat cells themselves to break down stored fat and slow the making of new fat.
The appeal is that AOD-9604 was built to be the safe half of growth hormone. Researchers at Monash University in the 1990s took the part of the growth hormone molecule associated with fat metabolism and left behind the parts that raise IGF-1 and disturb blood sugar. On that measure it worked: across roughly 900 participants in six trials there were no rise in IGF-1, the growth hormone marker, no blood sugar problems and no notable safety signal.
So people add it to a GLP-1 hoping for extra fat loss on top of appetite suppression, without the blood sugar and IGF-1 problems the growth hormone compounds bring.
Both had a promising Phase 2. Only one survived the bigger trial.
The test that separates a real compound from a hopeful one is whether an early positive result holds up when the trial gets larger. Both of these had that test.
The Phase 2b trial is the single most important fact about AOD-9604, and most vendor pages leave it out entirely.[7] It was large enough to detect a real effect, it ran for twice as long as the positive study, and it tested three doses. None of them beat a placebo.
The sources cannot quite agree on the trial itself, which is its own kind of evidence. Three describe 536 subjects and one says 534. Three describe a 24-week trial and one calls it twelve weeks.[1][2][3] We have used the majority figures throughout this page. The disagreement exists because there is no paper to check against, only investor communications and secondhand accounts, and that is the clearest signal of what happens when a result goes unpublished.
There is a real argument that the trial tested an oral form and that injection might behave differently. It is worth knowing that the argument has never been tested, that the company holding the compound chose to stop rather than run that study, and that nineteen years have passed since.
Safe, and that is a different claim from working.
AOD-9604 has an unusually clean safety record for this category. Around 900 participants across six trials, no IGF-1 elevation, no glucose disturbance, no notable adverse signal.[3] It even holds GRAS status, the FDA category for ingredients generally recognised as safe in food, which almost nothing else in peptides does.[1]
Those are two separate findings and they both hold. The compound appears safe and the one adequately powered trial found it did not work. A clean safety profile on an ineffective compound means the cost is money and injections instead of harm.
Against that, retatrutide on its own produced 28.3% average weight loss over 80 weeks. Anyone adding AOD-9604 to it is adding the weaker half by a very wide margin, to a compound already doing more than any other tested.
The half that works has the side effects.
AOD-9604's clean safety record is easy to read as a reason to add it. The compound it is being added to is the one worth knowing about.
In TRIUMPH-1, at the top dose against placebo: nausea in 42.4% against 14.8%, diarrhoea 32.0% against 13.5%, constipation 26.1% against 10.9%, vomiting 25.3% against 4.8%. About 11.3% stopped because of side effects, against 4.9% on placebo.[9]
Heart rate rose by around 6.7 beats per minute at the top dose, higher than tirzepatide or semaglutide produce, and that traces to the glucagon receptor retatrutide adds.[9] Most of the stomach and gut effects appear in the first week or two after each dose increase and settle over about four to six weeks.
Adding a compound with no measurable effect does not change any of that. The tesamorelin version of this stack covers the full side effect picture, including what people buying online report compared with trial participants.
Neither is approved, and both are banned in sport.
Retatrutide is not approved by any regulator anywhere. Five Phase 3 trials have reported positive results and a US filing is planned for the first quarter of 2027.[5]
AOD-9604 has no approved use anywhere. As of April 2026 it sits in Category 2 on the FDA's 503A list, the register of ingredients compounding pharmacies may work with. Category 2 means not allowed, pending further review.[1] It also sits under section S2 of the WADA prohibited list, banned in competition and out of it.[4]
Retatrutide's regulatory position comes from a compound that works and has not finished the process. AOD-9604's comes from a compound that finished the process and did not work.
What people ask about this stack
Does AOD-9604 work for fat loss?
Its only human trial large enough to answer the question says no. A 24-week Phase 2b study in 536 obese adults tested three doses against placebo and no arm produced statistically significant weight loss. Metabolic Pharmaceuticals terminated development in March 2007 on that result. An earlier and smaller 12-week study had shown 2.6 kg against 0.8 kg on placebo, and that finding did not replicate in the larger trial.
Is AOD-9604 safe?
By the available evidence, yes. Roughly 900 participants across six trials produced no IGF-1 elevations, no glucose problems and no notable adverse signal. It also holds GRAS status as a dietary ingredient. Safety and efficacy are separate questions, and this compound has a good answer to one of them.
Why do sources give different numbers for the trial?
Because there is no published paper to check against. Three accounts say 536 subjects and one says 534. Three say the trial ran 24 weeks and one says twelve. We use the majority figures. Every source agrees on the thing that matters, which is that the primary endpoint was not met at any dose and development stopped.
The failed trial was oral. Does injecting it change things?
Unknown. It is a fair question and nobody has run the study. The company holding the compound chose to end development rather than test an injectable version, and nineteen years have passed. Anyone injecting it today is relying on an untested assumption to explain away the one large trial that exists.
Has anyone studied the combination?
No study we could find has given retatrutide and AOD-9604 together, in people or animals. This is our own searching, not a systematic review, and we will correct this page for anyone who can point to a trial.
How does retatrutide compare?
In its Phase 3 programme it produced 28.3% average weight loss over 80 weeks at the top dose, against 2.1% to 3.2% on placebo across trials. Tirzepatide reached 22.5% and semaglutide 20.7% in their own trials. Retatrutide is the strongest result anyone has published, and it is not approved yet. The tesamorelin version of this stack covers its trial record in detail.
Can athletes use it?
No. AOD-9604 sits under section S2 of the WADA prohibited list, banned in competition and out of it, for any athlete subject to testing. Compare against the other stacks.
What this page is built on
Every source we checked reports the AOD-9604 Phase 2b result the same way. None of them links to a published paper, because the detailed results were never published. Where this page says a result was not statistically significant, it means the difference from placebo was small enough that chance could explain it.
- 01AOD-9604 evidence and status review. Source for the 24-week Phase 2b trial in 536 subjects failing its primary endpoint, the FDA Category 2 classification as of April 2026, the Australian regulator rejecting an obesity indication, GRAS status for dietary supplement use, and the 2013 Misra review in Current Cardiology Reviews documenting the 2007 termination.
- 02Phase IIb OPTIONS trial, 2006 to 2007. 536 obese subjects randomised to 0.25, 0.5 or 1 mg per day of oral AOD-9604 or placebo over 24 weeks. No treatment arm demonstrated statistically significant weight loss against placebo. Metabolic Pharmaceuticals terminated development in March 2007.
- 03Earlier Phase 2a result of 2.6 kg weight loss against 0.8 kg on placebo over 12 weeks, and the safety database of over 900 participants across six trials with no IGF-1 elevation and no glucose disturbance.
- 04AOD-9604 under section S2 of the WADA prohibited list, in competition and out of competition, and the note that the detailed Phase 2b results were never published in a peer-reviewed journal.
- 05Retatrutide Phase 3 programme. TRIUMPH-1 NCT05929066, 2,339 adults over 80 weeks, 28.3% at the top dose. The lead registration is NCT05567796. Four further Phase 3 trials in type 2 diabetes, established heart disease and knee osteoarthritis. US filing planned for the first quarter of 2027.
- 06Jastreboff et al., phase 2 obesity trial of retatrutide. New England Journal of Medicine, 2023. 24.2% at the top dose at 48 weeks against 2.1% on placebo.
- 07Assessment that the Phase 2b failure is the most important clinical fact about AOD-9604 and that most vendor pages omit it.
- 09TRIUMPH-1 adverse event figures against placebo, and the roughly 6.7 bpm heart rate rise at the top dose with its onset and settling pattern.
- 08Peptide Decoding vendor pricing data, 12 September 2026. Lowest in-stock single-compound listings: retatrutide $32.48, AOD-9604 $19.99.