Retatrutide: The Registry Record That Copies a Trial That Already Finished

Most entries here are about a compound whose reputation runs ahead of its evidence. Retatrutide is the reverse, and the most useful thing to say is still not the evidence.

The record that copies a finished trial

ClinicalTrials.gov carries a retatrutide entry, NCT07467447. Sponsor Hudson Biotech, classified as industry. Phase 2. Status recruiting. 300 estimated enrolment. One site, Peking University Shenzhen Hospital.

Its official title is character for character identical to that of Eli Lilly's NCT04881760: "A Phase 2 Study of Once-Weekly LY3437943 Compared With Placebo in Participants Who Have Obesity or Are Overweight With Weight-Related Comorbidities."

The detailed description reproduces its architecture too. Maintenance doses of 1, 4, 8 and 12 mg, 48 weeks of treatment, a Week 24 primary endpoint of percent change in body weight, alternative escalation schedules for the 4 mg and 8 mg arms. The real trial completed on 22 November 2022.

The credit for finding this cluster belongs elsewhere. On 31 July 2026, Morgan McSweeney published an investigation into eight registrations under that sponsor, all at the same single site, all submitted between 22 February and 14 March 2026, all marked recruiting. (Dr Noc)

Three say plainly what they are. The TB-500 entry opens "This fictional study is an example of a ClinicalTrials.gov-style record." The Melanotan II entry describes itself as "This example interventional study record." The tesamorelin entry carries "(Mock Study)" in its title. Two others clone Lilly assets: one reproduces the compound code LY3437943, the other the SURMOUNT-1 trial name and title verbatim. Lilly told that piece it has no relationship with the sponsor and did not authorise use of its protocol identifiers or the SURMOUNT-1 name.

What this entry adds is one number. That piece identified two records as copies of real Lilly trials and noted the code LY3437943 among them, without naming retatrutide as the cloned compound.

Now the part that matters. I read the complete brief summary and detailed description of NCT07467447. Neither contains the word fictional, example, mock, simulated, hypothetical or illustrative. Not once. Its acronym, GZBF, also mimics Lilly's protocol code convention, which runs to codes such as the genuine J1I-MC-GZBK. Any screen looking for the giveaway words passes this record through, and it is marked recruiting.

Think of a sheet of notes off one press. Three carry the word SPECIMEN across the face. The fourth does not, and its serial number was copied off a real bill. Nobody looks at the fourth and calls it currency.

NCT07467447 is the one retatrutide registry entry that must never be cited. Every other retatrutide record I checked, sixteen, is an Eli Lilly registration with no fictional, example or mock language. The cluster is covered from another angle in the BPC-157 entry.

What it is

Retatrutide, developed as LY3437943, is a single peptide with agonist activity at three receptors: those for glucose dependent insulinotropic polypeptide, glucagon like peptide 1, and glucagon. (PMID 35985340) Lilly describes it as an amino acid sequence carrying a C20 fatty diacid moiety that enables albumin binding. Half life is approximately 6 days, supporting once weekly subcutaneous dosing. (PMID 36354040)

Triple agonist is not the same as balanced agonist, and the difference is on Lilly's own page. In vitro the molecule is 8.9 fold greater than human GIP at the GIP receptor, 2.5 fold less than GLP-1 at the GLP-1 receptor, and 2.9 fold less than glucagon at the glucagon receptor.

Triple agonist describes the molecule the way three notes describes a chord. It tells you what is in there and nothing about which one you hear. On those numbers, the loud note is GIP.

What the phase 2 trials found

The pivotal obesity trial randomised 338 adults, with a BMI of 30 or above, or 27 to 29.9 with a weight related condition, to once weekly retatrutide at 1, 4, 8 or 12 mg or placebo for 48 weeks. NCT04881760, sponsor Eli Lilly and Company, completed 22 November 2022. (PMID 37366315)

Weekly dose	Weight loss at 24 weeks	Weight loss at 48 weeks
1 mg	7.2%	8.7%
4 mg	12.9%	17.1%
8 mg	17.3%	22.8%
12 mg	17.5%	24.2%
Placebo	1.6%	2.1%

Look at the two middle rows at 24 weeks. 17.3% and 17.5%. At the halfway mark, going from 8 mg to 12 mg bought 0.2 percentage points. Those arms separate only in the back half. Adverse events were predominantly gastrointestinal, dose related and mostly mild to moderate. Heart rate increases peaked at 24 weeks, then declined.

Phase 2 also ran in type 2 diabetes, where HbA1c fell up to 2.02% (PMID 37385280), and a liver fat substudy found reductions up to 82.4% (PMID 38858523).

What phase 3 found

TRIUMPH-1, NCT05929066, is a real Lilly master protocol. 2,335 participants, testing 4, 9 and 12 mg. At 80 weeks the efficacy estimand gave 19.0%, 25.9% and 28.3% weight loss against 2.2% on placebo. The treatment regimen estimand, the more conservative real world figure, came in at 17.6%, 23.7% and 25.0%. Announced by the company on 21 May 2026 and not published in a peer reviewed journal.

The ceiling shows in tolerability. At 12 mg against placebo, nausea ran 42.4% versus 14.8% and vomiting 25.3% versus 4.8%. Discontinuation for adverse events was 4.1% on 4 mg, 6.9% on 9 mg and 11.3% on 12 mg, against 4.9% on placebo. More than one in nine stopped the top dose.

Three further trials reported top dose weight loss of 20.8%, 22.6% and 28.7%. The last, in knee osteoarthritis, reported its largest pain reduction on the 9 mg arm, 4.5 WOMAC points against 4.4 on 12 mg. That attribution gets flipped constantly.

The first phase 3 diabetes readout is peer reviewed. TRANSCEND-T2D-1, in The Lancet on 6 June 2026: 537 adults, 40 weeks, A1C down 1.69% to 1.94% against 0.81% on placebo, no severe hypoglycaemia. (PMID 42250575) The outcomes trials have not reported.

Not approved anywhere

Lilly's own medical information is unqualified: retatrutide is investigational and not approved in any country or geography, and the 23 July 2026 release adds that it cannot be legally sold or marketed for human use. Every gram in civilian hands came from outside the legitimate supply chain.

One published legal path exists outside a trial: NCT07629401, an Eli Lilly individual patient expanded access record, status Available, physician initiated and case by case. As of 23 July 2026 Lilly had not filed a marketing application and said it plans to file in the first quarter of 2027, specifying a Biologics License Application rather than a New Drug Application. Reported verbatim, not interpreted.

The grey market

Public Citizen counted 14 hospitalisations connected to retatrutide in FDA's adverse event system by June 2026. (Public Citizen) The only peer reviewed report of harm I could find is a single case. A 32 year old man who bought retatrutide online escalated from 10 mg to 20 mg weekly, then injected a second dose the next day after forgetting the first, roughly 40 mg across two days. He presented with a week of intractable diarrhoea, dehydration and acute kidney injury, and recovered. It is not indexed in PubMed, so DOI 10.7326/aimcc.2025.1218 is the only identifier, and the journal would not load for me, so it is reported from secondary coverage rather than the primary record.

Then a preprint, not peer reviewed, analysing Reddit discussion of grey market use to December 2025. Among 13,589 users reporting current use, 7,823 had at least one mapped symptom. The most frequent reports were appetite increase, fatigue, increased energy, nausea and insomnia, not the gastrointestinal events of the trials. (DOI 10.64898/2026.05.28.26352819)

The top self reported effect of a drug whose entire mechanism is appetite suppression was increased appetite. No published explanation exists. Underdosed, degraded or misidentified product, reporting artefact and rebound after dose gaps are untested hypotheses. The preprint advances no mechanism beyond recommending pharmacovigilance.

Analytical work would settle much of that, and I could not find a single peer reviewed chemical analysis of grey market retatrutide product. That is a statement about my search, not a claim that none exists. The nearest analogue tested semaglutide instead: three vials bought online came back at 7.70% to 14.37% purity against a claimed 99%. (PMID 39509151) Results on one peptide are not results on another. That study is covered in the semaglutide entry.

The only vial level numbers I could find are vendor commissioned. A third party test on a BulkGLP 10 mg vial reported 99.76% purity but measured content of 12.05 mg against the 10 mg label, 121% of stated, on a sample disclosed as shop provided, not bought at retail. No sterility or endotoxin screen. (Peptigrity) Anyone dosing by that label is under informed. Reading a content line is walked through on an annotated retatrutide certificate in how to read a COA.

Where the circulating numbers come from

Reported as convention, because that is what it is. The reconstitution taught across vendor charts is 2 mL of bacteriostatic water into a 10 mg vial, giving 5 mg/mL, at which 1 mg is 20 units on a U-100 insulin syringe. Vial sizes vary by vendor; the guide I worked from references 10, 12, 24, 30 and 60 mg vials. No trial supplied drug this way.

The convention does not track the trial ladder. It splits in two directions from it.

1

2

3

4

0.1

1

10

mg per week · log scale

derived from researchcommunity convention

1. 1The circulating starting range · 0.25 to 1.5 mg per weekCharts start at 0.25 to 0.5 mg weekly, some splitting the week across three injections. No published trial used sub 1 mg as a maintenance target, or split dosing. The phase 2 diabetes 0.5 mg arm is the only published sub 1 mg exposure.
2. 2The circulating maintenance target · 4 mg per weekThe steady state those charts aim at, and the lowest maintenance dose in phase 3.
3. 3The highest dose in any published trial · 12 mg per weekPhase 2 used 1, 4, 8 and 12 mg, phase 3 used 4, 9 and 12 mg. No Lilly release or registry record I examined supports a 15 mg arm.
4. 4The dose in the one published case report · 20 mg per weekOne patient, not a norm. 20 mg is two thirds again the highest dose given in any trial, and 10 mg is not a dose any trial used. Both are vial numbers rather than trial doses: 10 mg is a standard vial, 20 mg two.

What nobody knows

Why appetite increase is the top self reported effect. It inverts the mechanism, it comes from 13,589 people, and nobody has published an explanation.

How widely the mis-transcribed ladder circulates. The registry shows the 12 mg arm started at 2 mg, so the "1 then 4 then 8 then 12" ladder people copy is not what the trial did. Whether that mistake is common or occasional would take a survey I have not run. It stays an impression, not a finding.

Regulatory status

FDA compounding. Retatrutide fails all three statutory gateways. It is not the subject of a USP or NF monograph, not a component of an FDA approved drug product, and not on the 503A or 503B bulks list. The shortage exemption that covered semaglutide never applied, because there is no approved product to be in shortage. FDA's bulks list page would not load for me, so this is taken from FDA's letter to the Federation of State Medical Boards.

FDA enforcement. On 31 March 2026 FDA issued warning letters to seven peptide sellers, posted 7 April 2026, decoding the obfuscated product names "GLP-3 RT" and "GLP1-R" as retatrutide. A research use only label does not exempt a product intended for human use. I could not load the letters, so that is reported from the warning letter index and industry summaries, not the primary record.

WADA. Retatrutide does not appear by name on the 2026 Prohibited List or Monitoring Program as far as I could find. That is not a reprieve. Category S0 captures any substance with no current approval by any governmental regulatory health authority for human therapeutic use, expressly including drugs under clinical development, and is prohibited at all times. Lilly says the compound is approved nowhere, so it lands in S0 by category. A therapeutic use exemption would not realistically be granted either, because the criteria require a legitimate therapeutic use an investigational drug cannot demonstrate. WADA's documents would not load for me, so that is reported from the Athletics Integrity Unit rather than the primary record.

My take

The evidence is not the weak point here, which is unusual for this reference. The trials were large, the results held across four conditions, and the tolerability ceiling is visible rather than buried.

The weak points are downstream. It is approved nowhere, so anything anyone holds came through a channel with no assay behind it. The one public analytical result on a retatrutide vial is vendor commissioned and found 21% more drug than the label claimed. The circulating doses are vial arithmetic, not trial arithmetic.

Then there is the registry record. It is a photocopy of real work filed under a new sponsor with a new date, and the only member of its family that does not confess. It reproduces the alternative escalation schedules for the 4 mg and 8 mg arms, a level of detail you reach for only if you want it to survive being read. The genuine trials produced better numbers than the copy claims to be looking for. It is still there, marked recruiting.

If you have a certificate of analysis for the batch you are actually holding, I would like to know what the content line said against the label. One vial came back at 121% of stated. I have no idea whether that is typical, and neither does anyone else.

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This content is for educational and informational purposes only and is not medical advice. Peptides discussed are research compounds and may not be approved for human use. Nothing here should be used to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any peptide, supplement, or protocol. Individual responses vary. Do not self-administer compounds without proper medical supervision.