What Is Retatrutide? The Molecule and the Vial
What is retatrutide: an investigational Eli Lilly triple receptor agonist with real published human trial data and no marketing approval in any country.
MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
What is retatrutide, answered plainly: an investigational injectable agonist developed by Eli Lilly that acts at three receptors, the GIP receptor, the GLP-1 receptor and the glucagon receptor. It breaks the pattern of every other compound covered on this site, and it breaks it in the direction people do not expect. There is substantial published human trial evidence. There is also no approval anywhere in the world.
Both halves have to be carried in the same sentence or the answer misleads. Saying the evidence is thin would be false. Saying it is available would also be false. The gap here is regulatory, not evidential, which is the opposite of the usual situation on this site and demands a different kind of care.
Lowest cost per milligram we track
Retatrutide — Ascension Peptides
Independently assayed research material. With the code the 30 mg works out at $3.33/mg and the 10 mg at $4.00/mg.
The certificate that resolves for this compound is MZ Biolabs lot 03-01260229, reporting 99.94 percent purity and 11.67 mg against a 10 mg label, purity and quantity only, with no endotoxin or sterility screen. A second certificate is linked on the product page and does not load. Buying 3, 5 or 10 takes 3%, 5% or 10% off the list price. Free shipping starts at $250.
- One third-party assay per batch
- Free carriage over $250
- Same-day dispatch before 2pm CST
Laboratory research material only, not for human consumption. Affiliate links: we may earn a commission at no additional cost to you. Figures checked September 9, 2026.
What is retatrutide established to do, and what is it not
| Statement | Status | Where it comes from | Organism |
|---|---|---|---|
| Acts at three receptors as a single agent | Established pharmacology | Published preclinical and clinical development work | Human and preclinical |
| Produced substantial mean weight reduction in a Phase 2 trial | Published result | Phase 2 report in the New England Journal of Medicine, 2023, Jastreboff et al. | Human |
| Phase 3 evaluation is under way | Ongoing, results not yet published | The TRIUMPH programme | Human |
| Approved for use in any country | No | No regulator has issued a marketing authorisation | Not applicable |
| Available on prescription anywhere | No | There is no dispensing route from any pharmacy | Not applicable |
| The material in a research vial matches its label | Unverified | A seller's claim, not an assay | Not applicable |
The first three rows are unusually strong for a compound discussed on sites like this one. The last three are unusually blunt. Reading only the top half produces the marketing version; reading only the bottom half produces the dismissive version; the compound is accurately described only by reading both.
The published trial, reported as a trial
The Phase 2 results appeared in the New England Journal of Medicine in 2023, authored by Jastreboff and colleagues. The trial reported roughly 24 percent mean weight reduction at 48 weeks in the group assigned to the 12 mg dose. The Phase 3 TRIUMPH programme is ongoing and has not reported.
Those are trial figures and they belong to the trial. Every part of what makes that number meaningful sits inside the study: participants who met entry criteria, a manufactured product of known content, a supervised escalation to the assigned amount, monitoring throughout, a comparison group, and follow up over the full 48 weeks. Detach the number from any of that and it stops being a result and becomes a target, which is a different kind of object entirely.
This page reports the figure because reporting it accurately is the only honest option, and it does not build anything on top of it. A mean across a trial group is not a prediction for an individual, and 48 weeks under monitoring is not a duration anyone can copy at a bench.
Unapproved everywhere is a separate fact from unevidenced
These two get collapsed constantly, in both directions, and keeping them apart is most of what a reader needs from this page.
Unevidenced means nobody has shown the compound does anything in people. That is the accurate description of most of the compounds on this site, and it is not the description of this one.
Unapproved means no regulator has completed a review and authorised a product. That is the accurate description of this compound today. It carries specific consequences: there is no approved label, so there is no regulator assessed dosing section and no regulator assessed adverse reactions section; there is no prescription route, so no pharmacy can dispense it; and there is no manufacturing oversight attached to anything sold as a research chemical, so what arrives in a vial is a claim.
The published trial establishes something about the molecule. It establishes nothing whatever about the vial, because the trial did not use the vial.
What the vial reduces to: a label and a fill volume
Strip the pharmacology away and a research vial is an arithmetic object with two inputs. The label states a mass. The person preparing it chooses a volume of diluent. Concentration is the first divided by the second, and every subsequent number derives from that ratio.
| Labelled mass | Diluent added | Concentration | Mass in one U-100 unit | Mass in 10 units |
|---|---|---|---|---|
| 5 mg | 1 mL | 5 mg per mL | 50 mcg | 0.5 mg |
| 5 mg | 2 mL | 2.5 mg per mL | 25 mcg | 0.25 mg |
| 10 mg | 1 mL | 10 mg per mL | 100 mcg | 1 mg |
| 10 mg | 2 mL | 5 mg per mL | 50 mcg | 0.5 mg |
| 10 mg | 4 mL | 2.5 mg per mL | 25 mcg | 0.25 mg |
Two facts live in that table and both are worth stating explicitly. A unit is a volume, fixed at 0.01 mL on a U-100 barrel, and it carries a different mass in every row. And the total material in the vial never changes with the fill volume: rows three, four and five all contain 10 mg, differing only in how that mass is spread across the liquid.
That is laboratory handling arithmetic. It answers what a stated concentration means and how a mark on a barrel maps to a volume. It answers nothing about what should be in the syringe.
One further comparison is available from the same two inputs and is worth doing before ordering rather than after. Cost per milligram is the vial price divided by the labelled mass, so a 10 mg vial at price P costs P divided by ten per milligram and a 5 mg vial at price S costs S divided by five. The larger container is the better value only when P is below twice S, which is a check rather than an assumption, since packaging premiums are not consistent between listings. Note also what does not enter that calculation: the diluent volume. Rows three, four and five of the table all describe the same 10 mg of material at the same cost per milligram, differing only in how thinly it is spread. No reconstitution choice has ever made a vial contain more.
The one calculation this page does not run
The obvious next step, and the reason this compound is more hazardous to write about than the others here, is that a real published figure exists. With a concentration in hand, converting a trial dose into a volume and a unit reading is one division. It is tempting precisely because it is easy.
It is not done here, and the refusal is not squeamishness about arithmetic. Division would reproduce the number and none of the conditions that made the number mean anything. The trial figure came at the end of a supervised escalation, using a product whose content was verified, in people selected against entry criteria, with monitoring and a comparison group. A vial from a research supplier supplies none of that. What the division would produce is a volume that looks like the trial and shares nothing with it except a digit.
There is a second reason, narrower and just as decisive. The trial dose was administered as a known mass of a known substance. A research vial's labelled mass is unverified, so the numerator in that calculation is a claim. An unverified numerator divided by a chosen denominator yields a confident looking figure resting on nothing, and the confidence is the dangerous part.
Frequently Asked Questions
Is it accurate to say there is no human evidence for this compound?expand_more
No, and that sentence would be wrong in a way that matters. Phase 2 results in humans were published in the New England Journal of Medicine in 2023, and Phase 3 work is ongoing. The accurate criticism is about approval and about product verification, not about evidence.
If the evidence is real, why is it not available anywhere?expand_more
Because evidence and authorisation are different stages. A regulator reviews a full dossier covering efficacy, safety and manufacturing before granting a marketing authorisation, and no regulator has completed that for this compound. Published trial results are an input to that process rather than a substitute for it.
Does the trial result tell a buyer what is in a research vial?expand_more
Not at all. The trial used a manufactured product with verified content. A vial sold as a research chemical carries a seller's label, and no assay accompanies it unless one is independently commissioned.
Why does this page state a concentration table but no amount?expand_more
Because the two are different kinds of statement. A concentration is a ratio derived from two numbers on the bench, and division cannot be wrong about it. An amount for a person is a claim about biology that only a trial and a regulator can support.
What would change the last three rows of the first table?expand_more
A completed regulatory review resulting in an approved product, which would supply an assessed label, a dispensing route and manufacturing oversight in one step. The Phase 3 programme reporting is a step toward that and is not the same thing as it.