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Retatrutide 10 mg
Peptide Library · Profile
Retatrutide 10 mg
Lilly's GIP/GLP-1/glucagon triple agonist — four reported Phase 3 trials and up to 28.3% body-weight reduction. The best-evidenced compound in this library, and the one where invented dosing schedules are most common elsewhere.
Molecular weight4,731.3Da
DosingWeeklysubcutaneous
Phase 3 trials reported4TRIUMPH-1 through 4
Peak weight loss28.3%80 wk, 12 mg, TRIUMPH-1
The short version
Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.
What it is
A once-weekly injectable that hits three receptors where semaglutide hits one. It is investigational — not approved anywhere in the world — and it is one of the few compounds Health Canada names by name in both its 2025 and 2026 peptide advisories.
What has actually been measured
Four reported phase 3 trials, with weight reduction up to 28.3% at 80 weeks on the 12 mg dose. On weight, this is the best-evidenced compound in the library.
What has not been measured
Whether it prevents anything. Every reported endpoint is body weight or blood sugar — not a heart attack, not a stroke, not a death.
What most people get wrong
The dosing. This is the compound where invented escalation schedules circulate most freely. The ladders actually used in the trials are published, and most of what gets passed around is not one of them.
What retatrutide is
Retatrutide (development code LY3437943) is Eli Lilly's single-molecule triple agonist at the GIP, GLP-1 and glucagon receptors. It is by a wide margin the most clinically advanced compound in this library: four Phase 3 TRIUMPH trials have reported results, and Lilly has stated it intends to file a Biologics License Application with the FDA by the first quarter of 2027.
No affiliation
Retatrutide is an investigational compound developed by Eli Lilly and Company, and every trial result on this page is from Lilly's published clinical programme. Sentient Biogenix is not affiliated with, endorsed by, sponsored by or supplied by Eli Lilly and Company. The material we supply is independently synthesised research-grade peptide sold for laboratory use only — it is not a Lilly pharmaceutical product, and no Lilly product is offered for sale here. Company and product names are used only to identify the compound and the published research accurately.
| Property | Value |
|---|---|
| Developer | Eli Lilly and Company |
| Code name | LY3437943 |
| Class | GIPR / GLP-1R / GCGR triple receptor agonist |
| Length | 39 amino acids, C-terminal amide |
| Molecular formula | C221H342N46O68 |
| Molecular weight | 4,731.3 g/mol |
| CAS number | 2381089-83-2 |
| Backbone | GIP-based, with two Aib substitutions and an α-methyl-leucine for protease resistance |
| Lipidation | C20 diacid on Lys17 via γ-Glu + AEEA spacer — drives albumin binding and weekly dosing |
How it works
The discovery paper characterises the in vitro profile as "balanced GCGR and GLP-1R activity but more GIPR activity."[5] Each arm contributes something different:
GLP-1R
Glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, and central appetite suppression. The familiar arm.
GIPR
Additional insulinotropic effect, central appetite modulation and adipose nutrient handling. Also appears to improve the gastrointestinal tolerability of the GLP-1 arm.
GCGR
The differentiator — increased energy expenditure plus hepatic lipid oxidation, which is what drives the very large liver-fat reductions.
The authors' own summary of the additive model: weight loss "was augmented by the addition of GCGR-mediated increases in energy expenditure to GIPR- and GLP-1R-driven calorie intake reduction." Semaglutide works on one of these three receptors; tirzepatide on two. The glucagon arm is also the most plausible contributor to the observed heart-rate increases, and the reason hepatic glucose output needed explicit monitoring in the diabetes programme.
Pharmacokinetics
Administered subcutaneously, once weekly. The pharmacokinetic profile supported weekly dosing in Phase 1, and the discovery paper notes that a reduction in body weight persisted up to day 43 after a single dose.[5]
A number we are deliberately not printing
A half-life of "about six days" circulates widely. Every instance of it we could trace led to a commercial vendor page rather than a peer-reviewed source — the primary Phase 1 pharmacokinetic paper (Urva et al., Lancet 2022) is paywalled and we have not been able to verify the point estimate against it. Weekly dosing across every trial is a fact; the specific half-life figure, for now, is not one we are prepared to assert.
What the evidence shows
This is the rare compound in this library where the honest answer is "quite a lot".
Phase 2, obesity — Jastreboff et al., New England Journal of Medicine 2023
338 adults with BMI ≥30, or ≥27 with a weight-related complication, without type 2 diabetes. Seven arms, 48 weeks.[1]
| Maintenance dose | Week 24 | Week 48 |
|---|---|---|
| Placebo | −1.6% | −2.1% |
| 1 mg | −7.2% | −8.7% |
| 4 mg | −12.9% | −17.1% |
| 8 mg | −17.3% | −22.8% |
| 12 mg | −17.5% | −24.2% |
24.2% ≈ 26.2 kg. Responder rates at 48 weeks on 12 mg: ≥5% loss in 100% of participants, ≥10% in 93%, ≥15% in 83%. Waist circumference fell 6.5–19.6 cm across the retatrutide arms versus 2.6 cm on placebo.
Phase 2, type 2 diabetes — Rosenstock et al., Lancet 2023
281 participants with HbA1c 7.0–10.5%, 36 weeks, with dulaglutide 1.5 mg as an active comparator.[2]
| Arm | ΔHbA1c at 24 wk | Δ weight at 36 wk |
|---|---|---|
| Placebo | −0.01% | −3.00% |
| Dulaglutide 1.5 mg | −1.41% | −2.02% |
| Retatrutide 4 mg | −1.30 to −1.39% | −7.92 to −10.37% |
| Retatrutide 8 mg | −1.88 to −1.99% | −16.34 to −16.81% |
| Retatrutide 12 mg | −2.02% | −16.94% |
All retatrutide arms except 0.5 mg beat placebo at p<0.0001. The 8 mg slow-escalation and 12 mg arms also beat dulaglutide. No severe hypoglycaemia and no deaths.
Phase 2a, MASLD — Sanyal et al., Nature Medicine 2024
98 participants with liver fat ≥10% by MRI-PDFF, embedded in the obesity trial.[3] Relative liver fat reduction at 48 weeks: −51.3% (1 mg), −59.0% (4 mg), −81.7% (8 mg), −86.0% (12 mg), versus −4.6% on placebo. Normalisation to under 5% liver fat was reached by 89% on 8 mg and 93% on 12 mg. No hepatotoxicity signal through 48 weeks.
Phase 3 — the TRIUMPH programme
Note that Phase 3 replaced the 8 mg step with 9 mg, so the maintenance doses are 4, 9 and 12 mg.
| Trial | n | Population | Duration | Weight loss, 12 mg |
|---|---|---|---|---|
| TRIUMPH-1 | 2,339 | Obesity / overweight | 80 wk | −28.3% (−70.3 lb) |
| TRIUMPH-2 | 1,152 | T2D + obesity | 80 wk | −20.8% · A1C −1.5 |
| TRIUMPH-3 | 1,949 | Severe obesity + CVD | 80 wk | −22.6% (−55.8 lb) |
| TRIUMPH-4 | 445 | Obesity + knee osteoarthritis | 68 wk | −28.7% (−32.3 kg) |
A prespecified 104-week extension in 532 TRIUMPH-1 participants with baseline BMI ≥35 reached 30.3%. That is a different endpoint from the headline 28.3% — the two are frequently conflated in secondary coverage. TRIUMPH-5, the head-to-head against tirzepatide, and TRIUMPH-Outcomes, a 248-week cardiovascular and renal outcomes trial, have not reported.
Dose escalation as studied
Why this section looks different to other sites
Many peptide reference pages publish a tidy week-by-week retatrutide ladder running 2 → 4 → 6 → 8 → 10 → 12 mg. No trial ever used a 6 mg or a 10 mg dose. Those schedules are invented, then presented with the authority of the trial data. What follows instead is the arm structure actually studied, which is both citable and more useful. It describes what investigators administered in trials — it is not a direction to administer anything to any person.
| Trial arm | Starting dose | Maintenance | Notes |
|---|---|---|---|
| 1 mg | 1 mg | 1 mg | No escalation |
| 4 mg, escalated | 2 mg | 4 mg | Stepped |
| 4 mg, direct | 4 mg | 4 mg | No escalation |
| 8 mg, slow | 2 mg | 8 mg | Best tolerability of the 8 mg arms |
| 8 mg, fast | 4 mg | 8 mg | Highest GI adverse event rate of any arm |
| 12 mg | 2 mg | 12 mg | Largest weight and HbA1c effect |
Escalation speed is not a formality — the trial proved it
In the Phase 2 diabetes trial, the 8 mg fast arm (4 mg start) recorded 50% gastrointestinal adverse events — the highest of any arm in the study. The 8 mg slow arm (2 mg start) reaching the same maintenance dose had better tolerability and slightly better outcomes on both HbA1c (−1.99% vs −1.88%) and weight (−16.81% vs −16.34%). Going up faster produced more side effects and no advantage.
The exact week boundaries at which each escalation step occurred sit in the NEJM and Lancet supplementary appendices, which we have not been able to retrieve. A four-week step interval is universally reported in secondary coverage; we have not confirmed it against protocol, so we are not printing it as fact.
Reconstitution
U-100 insulin syringe: 1 unit = 0.01 mL. Retatrutide amounts are in milligrams, not micrograms, which makes the draw volumes larger than most compounds in this library.
10 mg vial
| BAC water | Concentration | Per unit | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 1 mL ★ | 10 mg/mL | 0.10 mg | 20 u | 40 u | 80 u | 120 u ⚠ |
| 2 mL | 5 mg/mL | 0.05 mg | 40 u | 80 u | 160 u ⚠ | 240 u ⚠ |
| 3 mL | 3.33 mg/mL | 0.033 mg | 60 u | 120 u ⚠ | 240 u ⚠ | 360 u ⚠ |
20 mg vial
| BAC water | Concentration | Per unit | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 2 mL ★ | 10 mg/mL | 0.10 mg | 20 u | 40 u | 80 u | 120 u ⚠ |
| 3 mL | 6.67 mg/mL | 0.067 mg | 30 u | 60 u | 120 u ⚠ | 180 u ⚠ |
⚠ exceeds the 100-unit capacity of a standard 1 mL U-100 syringe and requires either a split draw or a more concentrated solution. ★ 10 mg/mL is the only concentration where every trial dose up to 8 mg fits in a single draw — 10 mg in 1 mL, or 20 mg in 2 mL. Check the vial physically holds the volume; a 3 mL vial will not take 5 mL.
Adverse events
Overall adverse event incidence in Phase 2 ran 73–94% on retatrutide versus 70% on placebo. Gastrointestinal events dominate, are dose-related, mostly mild to moderate, and concentrated during escalation.
| Trial | Nausea | Diarrhoea | Discontinuation for AE |
|---|---|---|---|
| TRIUMPH-1 | 28.6–42.4% (14.8% pbo) | 25.2–34.1% (13.5%) | 4.1 / 6.9 / 11.3% (4.9%) |
| TRIUMPH-2 | 13.7 / 20.8 / 28.0% (8.0%) | 27.4 / 33.5 / 33.6% (13.2%) | 3.8 / 11.6 / 7.7% (4.9%) |
| TRIUMPH-3 | 21.7 / 22.4% (5.8%) | 30.1 / 24.4% (8.7%) | 9.8 / 13.5% (4.8%) |
| TRIUMPH-4, 12 mg | 43.2% (10.7%) | 33.1% (13.4%) | 18.2% (4.0%) |
Signals worth naming individually
- Heart rate. Dose-dependent increase, peaking around week 24 then declining — consistent with the glucagon receptor arm.
- Dysesthesia. 20.9% at 12 mg versus 0.7% on placebo in TRIUMPH-4. This is not a prominent signal in the GLP-1 or GIP/GLP-1 class and is distinctive to retatrutide.
- Vomiting. 25.3% at 12 mg in TRIUMPH-1.
- No severe hypoglycaemia and no deaths in the Phase 2 diabetes trial.
- No hepatotoxicity signal through 48 weeks in the MASLD substudy.
The reason escalation exists
In the trials, escalation was managed by investigators who could pause, hold or step a participant down. Discontinuation for adverse events reached 18.2% at 12 mg in TRIUMPH-4. A static table cannot do what an investigator did, which is the honest limitation of any protocol published on a web page.
Regulatory and anti-doping status
- Not approved anywhere. Investigational worldwide. Lilly has stated an intent to file a BLA with FDA by Q1 2027.
- No approved labelling, dosing guidance or compounding pathway exists. Retatrutide is not on FDA's bulk drug substances lists.
- WADA: not named individually, but captured by category S0 — any pharmacological substance with no current approval by any governmental regulatory health authority for human therapeutic use. Prohibited at all times, in and out of competition. This status would change on approval.
Frequently asked
How does retatrutide differ from tirzepatide and semaglutide?
Semaglutide is a single GLP-1 receptor agonist. Tirzepatide is a dual GIP/GLP-1 agonist. Retatrutide adds a third arm — glucagon receptor agonism — which raises energy expenditure rather than only reducing intake. TRIUMPH-5 is the head-to-head against tirzepatide and has not reported.
What is the largest weight loss reported?
28.3% at 80 weeks on 12 mg in TRIUMPH-1, with 45.3% of participants losing at least 30% of body weight. A prespecified 104-week extension in participants with baseline BMI ≥35 reached 30.3% — a different endpoint that is often quoted as though it were the headline result.
Did escalation speed actually matter?
Measurably. The 8 mg fast-escalation arm in the Phase 2 diabetes trial had the highest gastrointestinal adverse event rate of any arm at 50%, while the slow-escalation arm reaching the same dose had better tolerability and marginally better HbA1c and weight outcomes.
Why does this page not give a week-by-week schedule?
Because publishing one would mean inventing dose steps that no trial used. The escalation structures above are what was actually studied and each carries an NEJM or Lancet citation. The exact week boundaries sit in supplementary appendices we have not been able to retrieve, and we would rather leave a gap than fill it with something unverifiable.
10 mg or 20 mg vial?
Purely a matter of reconstitution frequency and cost per milligram. The 20 mg vial at $150 works out to $7.50/mg against $9.00/mg for the 10 mg at $90. Reconstituted at 2 mL it gives the same 10 mg/mL as a 10 mg vial in 1 mL, so the draw arithmetic is identical.
What are the storage limits?
Lyophilised: about a year at −20 °C, two years at −80 °C, months refrigerated. Reconstituted: 2–8 °C, protected from light, no freeze–thaw. Figures of 28–56 days for reconstituted solution are a general peptide-handling convention — no retatrutide-specific stability study exists outside Lilly's own formulation work.
References
- Triple–hormone-receptor agonist retatrutide for obesity — a Phase 2 trial
Jastreboff AM et al. · New England Journal of Medicine · 2023;389(6):514–526 · PMID 37366315 · View source - Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo- and active-controlled, parallel-group, Phase 2 trial
Rosenstock J et al. · The Lancet · 2023;402(10401):529–544 · PMID 37385280 · View source - Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized Phase 2a trial
Sanyal AJ et al. · Nature Medicine · 2024;30(7):2037–2048 · View source - LY3437943, a novel triple GIP, GLP-1 and glucagon receptor agonist in people with type 2 diabetes: a Phase 1b multiple-ascending dose trial
Urva S et al. · The Lancet · 2022;400(10366):1869–1881 · PMID 36354040 · View source - LY3437943, a novel triple glucagon, GIP and GLP-1 receptor agonist: from discovery to clinical proof of concept
Coskun T et al. · Cell Metabolism · 2022;34(9):1234–1247 · PMID 35985340 · View source - Phase 2 obesity trial, including the MASLD substudy
ClinicalTrials.gov · NCT04881760 · View source - Phase 2 type 2 diabetes trial
ClinicalTrials.gov · NCT04867785 · View source - TRIUMPH-1
ClinicalTrials.gov · NCT05929066 · View source - TRIUMPH-2
ClinicalTrials.gov · NCT05929079 · View source - TRIUMPH-3
ClinicalTrials.gov · NCT05882045 · View source - TRIUMPH-Outcomes — 248-week cardiovascular and renal outcomes
ClinicalTrials.gov · NCT06383390 · View source - Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial
Eli Lilly and Company · 21 May 2026 · View source - Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials
Eli Lilly and Company · 23 July 2026 · View source - Prohibited List — S0 Non-Approved Substances
World Anti-Doping Agency · View source
For laboratory research use only. Not for human or veterinary use. Nothing on this page is dosing guidance, and no figure here should be read as a recommendation.