Tirzepatide: The Trials Are Real, Which Is Why Somebody Copied One

01What it is

Two gut hormones run this drug, glucose dependent insulinotropic polypeptide and glucagon like peptide 1, the signals that tell the body it has eaten. A 39 amino acid synthetic peptide that activates both the GIP and GLP-1 receptors, carrying a C20 fatty diacid that lets it be dosed once a week under the skin. (PMID 30473097) The dose range everything rests on came from a phase 2 diabetes trial: 318 patients, 26 weeks, tirzepatide at 1, 5, 10 and 15 mg weekly against dulaglutide and placebo. (PMID 30293770) Hold on to that 1 mg arm.

02What the trials found

HbA1c, the measure these diabetes trials turn on, is a blood test that reflects average blood sugar over recent months. SURPASS, for diabetes, is five numbered phase 3 trials plus an outcomes trial. SURPASS-2 is the one to look at: 40 weeks, 1,879 patients on metformin, against semaglutide 1 mg, with HbA1c falling 2.01, 2.24 and 2.30 points against 1.86. (PMID 34170647) SURPASS-CVOT put 6,586 patients against 6,579 on dulaglutide and met non-inferiority on cardiovascular death, heart attack or stroke combined. (PMID 41406444) Note what that is. An active comparator, not placebo, and superiority was not met.

SURMOUNT, for weight. SURMOUNT-1 is the big one, and the section after this one is about it. 72 weeks, double blind, placebo controlled, adults with obesity or overweight without diabetes. Weight change at 72 weeks was 15.0% at 5 mg, 19.5% at 10 mg and 20.9% at 15 mg, against 3.1% on placebo. (PMID 35658024)

SURMOUNT-4 is the one people forget. After a 36 week run-in, patients were randomised to keep going or switch to placebo, and the placebo group put the weight back on. (PMID 38078870) SURMOUNT-5 ran head to head at maximum tolerated doses, 20.2% against 13.7% for semaglutide. (PMID 40353578) The cleanest comparison anybody has run.

03The record that carries Lilly's protocol code

On 31 July 2026 Morgan McSweeney published an investigation into eight ClinicalTrials.gov records sharing one sponsor, Hudson Biotech, all of them recruiting, all naming a single site in Shenzhen. (Dr Noc) I ran the sponsor query and got the same eight. Six are grey market peptides, two use Eli Lilly compound codes, and three say in their own descriptions that they are examples.

The tirzepatide one is the worst. NCT07481747 clones SURMOUNT-1, recruiting, sample size 2,539, contact at a beijing-biotech.com domain. The title is character for character the real record's, and the sample size is what the real trial finished with, presented as an estimate for a trial that has not started.

Then the field that gives it away. The org study ID is I8F-MC-GPHK(b). I8F-MC-GPHK is Lilly's internal protocol code for SURMOUNT-1, listed as a secondary ID on the genuine record, and the clone has it with "(b)" tacked on the end. Search the registry for that string and exactly two records come back, Lilly's and this one, where there should only ever be one.

And nothing in it warns you. I read the brief summary and the detailed description and neither contains the word fictional, example, mock, simulated or synthetic. The only thing that caught this one was the sponsor.

Do not cite NCT07481747.

04How it compares

The evidence does not move sideways. A kidney failure figure belongs to the row it sits in.

05Where the dose came from

Label dosing, as label and not recommendation: 2.5 mg weekly for four weeks, then increases of 2.5 mg. Mounjaro is for glycaemic control in adults and children 10 and over with type 2 diabetes, capped at 15 mg in adults and 10 mg in children.

The convention defines a microdose as anything below the 2.5 mg label start, usually 0.25 to 1.5 mg weekly. I found those numbers only on vendor and telehealth pages.

One correction first. Randomised placebo controlled data below 1 mg does exist. Lilly's first in human study gave single doses from 0.25 mg and four weekly doses from 0.5 mg. But those measured how the drug behaves in the body and whether it was tolerated, not weight.

Here is the actual gap. The 1 mg arm of the phase 2 trial is the lowest tirzepatide dose ever carried through a randomised trial with a sustained weight endpoint, and it produced 0.9 kg over 26 weeks in people with type 2 diabetes. Protocols promising real weight loss at 0.5 to 1.5 mg are extrapolating past the only randomised weight data anywhere near their range, and that data is unflattering. (PMID 30293770)

Look closer, because the two effects do not shrink together. HbA1c fell 1.06 points at 1 mg against 1.94 at 15 mg, so on blood sugar the bottom dose kept more than half the effect, while on the scale it gave 0.9 kg out of a range reaching 11.3. An airliner throttled right back still runs its lights, its radios and its cabin air perfectly. None of that tells you it can leave the ground.

Side effects did not vanish down there either. In that same trial, gastrointestinal events ran 23.1% at 1 mg against 9.8% on placebo. (PMID 30293770) The practice has since been criticised in the peer reviewed nursing literature as anecdote driven. (PMID 42201545)

06What could go wrong

One note on sourcing first: FDA's copies of these documents errored every time I tried to fetch them and the court opinion was initially sealed, so this comes from industry summaries rather than the primary record, the Federal Register item excepted.

FDA took tirzepatide off the shortage list, the compounders sued, the court declined to stop the agency, and legal compounding ended. Then FDA moved to shut the door permanently, with a Federal Register notice proposing not to include semaglutide, tirzepatide and liraglutide on the 503B Bulks List, rejecting the argument that hyper-responders need sub-label doses. Patient preference, it says plainly, is not clinical need.

Separately the US International Trade Commission issued a general exclusion order, brought by Eli Lilly, banning imports of products containing tirzepatide and of "products purporting to contain tirzepatide."

A 2026 paper reports a previously unidentified impurity formed when tirzepatide reacts with certain vitamin B12 analogues, across ten samples from compounding pharmacies, medspas and telehealth networks. (PMID 42010938) All five authors are Eli Lilly employees, so that is the manufacturer testing a competitor category.

The branded products carry a warning of their own. Both labels carry a boxed warning for thyroid C-cell tumours, seen in rats with uncertain relevance to people.

07What nobody knows

Whether the small doses do anything worth having, since the only randomised weight data anywhere near them is the one arm above.

What is in a compounded or imported vial, which is why the exclusion order had to reach for the phrase purporting to contain.

What the impurity does to a person. The paper that reports it says the clinical effects are unknown.

08My take

Tirzepatide is the strangest entry here, because for once the science is not the problem. Somebody ran the trials, big and long and against active comparators, and published a withdrawal trial showing the weight comes back, which is not a result a sponsor volunteers unless the programme is honest. You cannot argue that nobody looked.

What has grown around that evidence moves two ways. Downward into doses tested exactly once, that did badly when they were. Sideways into compounded and imported product no trial ever used, where the regulator's own language has shifted to "purporting to contain."

Then there is the registry record. Every other fake in this project gave itself away in its own text. This one does not, because it was built by copying something genuine whole, file number included, which made it stronger everywhere except the one place a duplicate becomes visible. The evidence being real is what made it worth stealing.

Have you seen a clinic or telehealth site quote SURMOUNT-1's 20.9% while selling something that is not branded tirzepatide? Tell me which one, because that specific move is why this entry exists.

Frequently asked

Is tirzepatide FDA approved?+

Yes, twice. It is sold as Mounjaro for glycaemic control in type 2 diabetes, in adults and in children aged 10 and over, and as Zepbound for long term weight reduction in adults with obesity or with overweight plus a weight related condition, and for moderate to severe obstructive sleep apnoea in adults with obesity. Both labels carry a boxed warning for thyroid C-cell tumours, which were seen in rats and whose relevance to people is uncertain.

Is tirzepatide better than semaglutide for weight loss?+

On the measured endpoints of the trials that put it directly against semaglutide, tirzepatide came out ahead. SURMOUNT-5 compared the two at maximum tolerated doses and reported 20.2% weight loss against 13.7% for semaglutide, which is the cleanest comparison anybody has run.

Does microdosing tirzepatide actually work?+

The convention defines a microdose as anything under the 2.5 mg the label starts at, usually 0.25 to 1.5 mg weekly, and I found those numbers only on vendor and telehealth pages. The lowest tirzepatide dose ever carried through a randomised trial with a sustained weight endpoint is the 1 mg arm of the phase 2 diabetes trial, and it produced 0.9 kg over 26 weeks, against a range reaching 11.3 kg at the top of that same trial. Side effects did not vanish down there either, with gastrointestinal events at 23.1% on 1 mg against 9.8% on placebo. The practice has since been criticised in the peer reviewed nursing literature as anecdote driven.

Do you put the weight back on when you stop tirzepatide?+

SURMOUNT-4 is the trial that asked. After a 36 week run-in, patients were randomised either to keep going or to switch to placebo, and the placebo group put the weight back on. The sponsor published that one itself.

Is compounded tirzepatide the same as Mounjaro or Zepbound?+

No trial has used compounded material, so there is no trial answer to that. FDA took tirzepatide off the shortage list, the compounders sued, the court declined to stop the agency, and legal compounding ended. Separately, a 2026 paper reports a previously unidentified impurity that forms when tirzepatide reacts with certain vitamin B12 analogues, across ten samples from compounding pharmacies, medspas and telehealth networks. All five of its authors are Eli Lilly employees, and the paper says the clinical effects of that impurity are unknown.

Is NCT07481747 a real trial?+

No. It is a ClinicalTrials.gov record that clones the completed SURMOUNT-1 trial and is marked recruiting. Its org study ID is I8F-MC-GPHK(b), and I8F-MC-GPHK is Lilly's internal protocol code for SURMOUNT-1, listed as a secondary ID on the genuine record. Nothing in it warns you: I read the brief summary and the detailed description and neither contains the word fictional, example, mock, simulated or synthetic. It is not evidence and it should not be cited.

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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.