Retatrutide
Properties
| Substance class | Synthetic peptide of 39 amino acid residues, developed by Eli Lilly and Company under the code LY3437943. FDA's substance record gives the full systematic name, from which the structure can be read directly: three residues are non-standard (2-methylalanine at positions 2 and 20, 2-methyl-L-leucine at position 13), the C-terminus is a serinamide rather than a free acid, and the lysine at position 17 carries an N6 side chain built from L-gamma-glutamate, two units of 2-[2-(2-aminoethoxy)ethoxy]acetyl, and a 19-carboxy-1-oxononadecyl (C20 diacid) fatty-acid group. That acylation is the structural feature that distinguishes it from an unmodified peptide and underlies its long circulating persistence. | source |
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| Sequence | YAQGTFTSDYSILLDKKAQAAFIEYLLEGGPSSGAPPPS. READ THIS CAVEAT BEFORE USING THE STRING. FDA's substance registry renders the backbone in standard single-letter code, which silently flattens the three non-standard residues: the "A" at position 2 and the "A" at position 20 are 2-methylalanine (Aib), and the "L" at position 13 is 2-methyl-L-leucine. The string also omits the C-terminal amide and the acyl side chain on Lys17. It is a backbone index, not a synthesis specification. | source |
| Other names | LY3437943; LY-3437943. Registered as an International Nonproprietary Name (INN 12350) and a United States Adopted Name (USAN JK-35), unlike most compounds in this category, which circulate under common names that no naming body has ever assigned. | source |
| Cas number | 2381089-83-2 | source |
| Unii | NOP2Y096GV | source |
| Sodium salt identifiers | Retatrutide sodium is a separate registered substance from retatrutide, with its own UNII, LQ42M82ZU6. FDA's substance record for the sodium form carries no CAS number. As with BPC-157's free base and acetate forms, a source that says "retatrutide" may mean either, and a number attached to one does not transfer to the other without checking. | source |
| Molecular formula | C221H342N46O68. PROVENANCE: PubChem titles this record "Retatrutide (sodium salt)" although the formula it carries contains no sodium atom, so the depicted species is the free form. Recorded with that discrepancy stated rather than silently resolved. | source |
| Molecular weight | 4731 g/mol | source |
| Molecular weight independent measurement | An independent Australian laboratory analysis of products sold as retatrutide states the expected molecular weight of authentic retatrutide as 4730.477 Da, and reports that the measured molecular weights of all three samples it tested closely matched it. This is an independent analytical figure rather than a computed one, and it is recorded alongside the PubChem value rather than in place of it. Da | source |
| Mechanism | A single peptide with agonist activity at three receptors: the glucagon receptor (GCGR), the glucose-dependent insulinotropic polypeptide receptor (GIPR), and the glucagon-like peptide-1 receptor (GLP-1R). The originating Eli Lilly paper reports that in vitro it shows balanced GCGR and GLP-1R activity but more GIPR activity. | source |
| Distinction from single and dual agonists | The third receptor is the difference. Approved incretin products act at GLP-1R alone, or at GIPR and GLP-1R together; retatrutide adds glucagon receptor agonism. In the originating paper's obese-mouse experiments the authors attribute the additional body-weight effect to GCGR-mediated increases in energy expenditure layered on top of the GIPR- and GLP-1R-driven reduction in calorie intake. That mechanistic split is an animal finding from the discovery paper, not a human measurement. | source |
| Half life | Approximately 6 days in people with type 2 diabetes. Reported in the phase 1b multiple-ascending-dose trial (NCT04143802), which also found the pharmacokinetics to be dose proportional and concluded that they suggest suitability for once-weekly dosing. This is a trial measurement in a supervised setting, recorded as pharmacology, not as guidance. days | source |
| Dosing frequency in published trials | Every published trial below used once-weekly subcutaneous administration, with stepwise dose escalation from a low starting amount. This is a record of how the registered trials were designed. It is not a protocol, and nothing about it transfers outside a trial: the material, the escalation schedule, the monitoring and the discontinuation criteria were all controlled by the sponsor and the investigators. | source |
| Detection window in plasma | An anti-doping laboratory that developed an LC-HRMS method to World Anti-Doping Agency criteria reported limits of detection of 6.14 ng/mL in plasma and 2.44 ng/mL in urine, an extended plasma detection window of approximately 56 days after the first dose in four self-administering users, and that neither intact retatrutide nor metabolite-derived signals were detected in urine at any timepoint. Plasma concentration-time profiles were nonmonotonic, which the authors read as prolonged subcutaneous absorption with depot-like release. This is analytical chemistry, not a study of any effect in a person. | source |
| Storage | Not established, and there is no authority that could establish it. There is no approved product label for retatrutide in any country and no pharmacopoeial monograph, so no manufacturer storage condition, in-use period or shelf life has been published for it. FDA's published guidance on storage and in-use limits for GLP-1 products addresses compounded drugs; that guidance cannot be applied to retatrutide, because on the same page FDA states retatrutide "cannot be used in compounding under federal law". Any storage figure circulating for this compound therefore traces to a supplier page rather than to a determination by anyone. No peer-reviewed forced-degradation or shelf-life study for retatrutide was located during data entry. | source |
| Approval status | Not approved anywhere. FDA states, naming the substance directly, that retatrutide and cagrilintide "are not components of FDA-approved drugs and have not been found safe and effective for any condition." Page content current as of 09/01/2026. | source |
| Approval status outside the united states | Also none. A peer-reviewed Australian analysis published in September 2026 describes retatrutide as "not being approved for therapeutic use in Australia or internationally". Reporting on the phase 3 topline results, The Pharmaceutical Journal states that "The drug is currently an investigational molecule and does not have regulatory approval." | source |
| Fda compounding status | Prohibited. FDA's published statement reads "Retatrutide and cagrilintide cannot be used in compounding under federal law." On the same page FDA records that it has warned telehealth companies for marketing unapproved drugs such as retatrutide including by direct marketing to consumers, active pharmaceutical ingredient distributors for selling retatrutide and other GLP-1 drugs to compounders, and outsourcing facilities for repackaging retatrutide. This is a stricter position than the one FDA takes on compounds it is merely still evaluating for the 503A Bulks List. | source |
| Fda position on research use labelling | FDA states it "has warned companies that have illegally sold unapproved drugs containing semaglutide, tirzepatide, retatrutide, survodutide or mazdutide that are falsely labeled 'for research purposes' or 'not for human consumption.'" The agency's position is that such labelling does not determine regulatory status; the seller's own marketing does. | source |
| Fda enforcement position | In a warning letter dated March 31, 2026 to a firm offering a product it called "Retatrutide" (and also "GLP-1-R peptide"), FDA's Center for Drug Evaluation and Research stated "these products are unapproved new drugs under section 505(a) of the Federal Food, Drug, and Cosmetic Act" and that introducing them into interstate commerce violates the Act. FDA wrote that despite the firm's "Research Use Only" and "not intended for human consumption" labelling, evidence from its website established that the products were intended to be drugs for human use. The determination attaches to that firm's products as marketed with those claims; it is not a finding about the molecule in the abstract. | source |
| Regulatory submission status | No marketing application has been filed. Reporting Lilly's July 23, 2026 announcement of two further phase 3 results, Pharmaceutical Executive records that Lilly "plans to submit a biologics license application for U.S. approval in the first quarter of 2027" and is completing the chemistry, manufacturing and controls data package required for it. An announced intention to file is not a filing, and a filing is not an approval. | source |
| Expanded access programme | A pre-approval expanded access record, NCT07629401, was first posted on June 5, 2026 and is listed as available. It provides single-patient access for adults with severe obesity and at least two serious or life-threatening obesity-related complications who are refractory to the best approved therapy and cannot enrol in a trial. Requests must be initiated by the patient's own physician; the record states that patients and caregivers should be directed to their physician rather than contacting the sponsor. This is the only route outside a clinical trial that the sponsor operates, and it is not a consumer route. | source |
| Trial programme size | 33 registered studies with retatrutide as an intervention, as returned by the ClinicalTrials.gov API on 2026-09-16: 14 phase 1, 4 phase 2, 14 phase 3, and 1 expanded access record carrying no phase. 32 of the 33 list Eli Lilly and Company as lead sponsor; the remaining one lists Hudson Biotech. Registered enrolment ranges from 29 participants in a renal impairment study to 10000 in the cardiovascular and kidney outcomes trial. | source |
| Indications studied | Per the registered conditions fields on ClinicalTrials.gov: obesity and overweight, type 2 diabetes, knee osteoarthritis, obstructive sleep apnea, chronic kidney disease, atherosclerotic cardiovascular disease, metabolic dysfunction-associated steatotic liver disease, chronic low back pain, and maintenance of weight reduction. Also registered are phase 1 studies in healthy participants, in renal and hepatic impairment, in Japanese and Chinese participants, and drug-drug interaction studies. Listing a condition as studied is not a statement that anything was shown for it. | source |
| Phase 3 programme structure | The registrational programme, TRIUMPH, consists of four phase 3 multicentre randomised double-blind studies of weekly subcutaneous retatrutide against placebo in over 5800 participants, using a basket design that evaluates obesity and two related complications, obstructive sleep apnea and knee osteoarthritis, at the same time. TRIUMPH-1 and TRIUMPH-2 are the two weight-management basket trials. Separate phase 3 programmes cover type 2 diabetes (TRANSCEND) and cardiovascular and kidney outcomes (TRIUMPH-Outcomes, NCT06383390). | source |
| Anti doping status | Not established by any source this file could verify, and deliberately not inferred. No statement from a national or international anti-doping authority naming retatrutide was retrievable during data entry. What was verified is narrower: the United States Anti-Doping Agency publishes that "GLP-1s are not prohibited in sport" and that the World Anti-Doping Agency is monitoring their use to determine whether they should be prohibited in future. That page names semaglutide, dulaglutide and exenatide, all of them approved drugs; it does not name retatrutide, and retatrutide differs from every product it does name in not being approved by any health authority. This site does not extend that statement to retatrutide in either direction. Athletes should ask their own anti-doping authority rather than rely on this entry. | source |
| Composition of non pharmaceutical supply | Measured once, in a small independent sample, and it did not match the label. An Australian analysis of three products sold as retatrutide and labelled as containing 10 mg each found that all three did contain retatrutide by molecular weight, but that content per vial was 5.13 mg (51.3% of labelled), 16.5 mg (165.0%) and 19.0 mg (190.0%) — roughly half to almost double the labelled amount. Elemental impurity testing found no arsenic, cadmium, chromium, nickel or mercury above quantitation limits; lead was detected at 0.7 mg/kg, copper at 0.9 mg/kg and zinc at 3.7 mg/kg, all of which the authors interpreted as substantially below toxicologically relevant exposure thresholds. Their conclusion was that "inaccurate dosing alone may represent an important source of risk". | source |
What the research does not show
- The central limitation of this compound is not weak evidence. It is the gap between the evidence and the supply. Retatrutide has completed phase 3 trials in thousands of participants, and it is simultaneously approved nowhere, prohibited in compounding by FDA, and available to consumers only through channels that no regulator oversees. Strong trial results are not a lawful route to the substance and say nothing about material obtained outside one. source
- Every clinical figure on this page was produced with material manufactured by the sponsor to pharmaceutical standards, administered on a fixed escalation schedule under medical supervision, with protocol criteria for stopping. None of those conditions holds outside a trial, and the trials measured nothing about material bought elsewhere. source
- The identity and content of non-pharmaceutical supply is not characterised. The only independent analysis located tested three products sold as retatrutide in Australia and found content ranging from 51.3% to 190.0% of the labelled amount. Its authors state plainly that only three samples were analysed and that the findings may not reflect the broader illicit peptide market. A three-sample study is the entire published evidence base on what is actually in these products. source
- Detailed results for most of the phase 3 programme have not been published or peer reviewed. As of this entry, of the completed phase 3 studies only TRANSCEND-T2D-1 has appeared as a full paper. TRIUMPH-1, TRIUMPH-2, TRIUMPH-3 and TRIUMPH-4 have been announced as sponsor topline results and reported by the trade and professional press; the sponsor states detailed results will be presented at future meetings and published later. None of the completed phase 3 studies had results posted on ClinicalTrials.gov when this file was written. Figures quoted from those announcements are sponsor-reported and have not been through external review. source
- The evidence base is almost entirely industry-run. 32 of the 33 registered studies list Eli Lilly and Company as lead sponsor, and the published trials are authored substantially by Lilly employees and shareholders, as their own declaration-of-interests statements record. This is normal for a drug in development and it is not an accusation; it does mean there is no large independent replication of any of these results. source
- Long-term safety is not established. The longest published or announced follow-up in the programme is 104 weeks. Cardiovascular and kidney outcomes remain under study in TRIUMPH-Outcomes (NCT06383390), a trial with a registered enrolment of 10000 that has not reported. In TRIUMPH-3, neither the wider nor the narrower composite cardiovascular endpoint reached statistical significance, with hazard ratios of 0.82 (95% CI 0.55 to 1.22) and 1.12 (95% CI 0.64 to 1.96) respectively and confidence intervals wide enough to be consistent with benefit or with harm. source
- Discontinuation because of adverse events was common at the higher doses and rose with dose. TRIUMPH-1 reported discontinuation rates owing to adverse events of 4.1%, 6.9% and 11.3% across its three doses against 4.9% with placebo. TRIUMPH-4 reported 12.2% and 18.2% at its two doses against 4.0% with placebo. A result reported for people who stayed in a trial is not a result for everyone who started it. source
- Adverse events were frequent, not incidental. In the phase 3 obesity trial TRIUMPH-1, participants on the highest dose reported nausea (42.4%), diarrhoea (32.0%), constipation (26.1%) and vomiting (25.3%), and dysesthesia and urinary tract infections were reported in around one in ten participants on the highest doses. These were events recorded under medical supervision, with the option to reduce dose or stop. source
- Populations the trials excluded were not studied, and the trials cannot be read across to them. A published case report describes a man in his mid-30s with longstanding type 1 diabetes who presented with severe vomiting, diarrhoea, hyperglycaemia, ketonaemia and acute kidney injury shortly after self-administering an online-purchased product marketed as retatrutide. The report's authors state that retatrutide "has no established role in type 1 diabetes mellitus", and that causation cannot be established in the case because a concurrent Shigella flexneri infection was also present. source
- There is no established storage condition, in-use period, or shelf life. No approved product label exists in any country and there is no pharmacopoeial monograph, so nobody with the standing to determine handling conditions has done so. No peer-reviewed forced-degradation or shelf-life study for retatrutide was located. source
- The published research does not establish a dose, a route, a schedule, a duration, or a formulation for use by anyone outside a clinical trial. The escalation schedules used in the trials were designed alongside supervision, monitoring and stopping rules that do not exist outside them, and the trials were not designed to answer what happens without those.
- The anti-doping position is unresolved rather than permissive. No anti-doping authority statement naming retatrutide was retrievable during data entry. The statement that does exist covers GLP-1 agonists as a class and names only approved products; whether it reaches an unapproved triple agonist is a question this file does not answer. An anti-doping laboratory has separately published a validated detection method for retatrutide, citing increasing use among physically active populations. source
- The molecular record itself carries an unresolved discrepancy. PubChem titles its record "Retatrutide (sodium salt)" while listing a formula containing no sodium, and FDA registers retatrutide and retatrutide sodium as two substances with different UNII codes. A figure attached to "retatrutide" in a third-party source cannot be assumed to belong to either form without checking which one the source meant. source
- Nothing here has been evaluated for use in anyone. There is no regulatory finding of safety or effectiveness for retatrutide for any condition, anywhere. An announced intention to file a marketing application is not a finding, and this page should not be read as anticipating one.
Storage and handling
Not established, and there is no authority that could establish it. There is no approved product label for retatrutide in any country and no pharmacopoeial monograph, so no manufacturer storage condition, in-use period or shelf life has been published for it. FDA's published guidance on storage and in-use limits for GLP-1 products addresses compounded drugs; that guidance cannot be applied to retatrutide, because on the same page FDA states retatrutide "cannot be used in compounding under federal law". Any storage figure circulating for this compound therefore traces to a supplier page rather than to a determination by anyone. No peer-reviewed forced-degradation or shelf-life study for retatrutide was located during data entry. source
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