DEEP DIVE

Retatrutide

What is retatrutide?

Retatrutide is a research peptide that activates three hormone receptors: GLP-1, GIP and glucagon. Receptors are proteins that receive signals. Human trials study defined clinical preparations, not the research vials in this catalog.

Last updated: 2026-10-08

At a Glance

Full Name: Retatrutide (LY3437943)

Developer: Eli Lilly and Company

Class: Triple hormone receptor agonist

Targets: GLP-1 + GIP + Glucagon receptors

Structure: 39-amino acid peptide with C20 fatty diacid moiety

CAS Number: 2381089-83-2

Molecular Formula: C₂₂₅H₃₄₈N₄₈O₆₈S

Clinical Stage: Phase 3 (TRIUMPH program — 8 trials)

FDA Status: Investigational (approval projected ~2027)

IN THIS ARTICLE

Why is Retatrutide studied?How does Retatrutide work in research models?What does the evidence show?Retatrutide vs. Semaglutide vs. Tirzepatide What are the limits of the safety evidence?What questions remain for future research?FAQ References

Why is Retatrutide studied?

Retatrutide adds glucagon receptor activity to GLP-1 and GIP activity. This triple-target design is a major research focus. It differs from single and dual receptor compounds.

The cited 2023 phase 2 trial studied body-weight outcomes in adults with obesity. Later TRIUMPH material includes sponsor announcements. A sponsor announcement and a peer-reviewed paper are different evidence sources.

Results from separate trials cannot establish which compound is best. Participants, methods and follow-up can differ. Each result needs its own study context.

How does Retatrutide work in research models?

An agonist activates a receptor. Retatrutide is studied as an agonist at GLP-1, GIP and glucagon receptors. Each receives a different hormone signal.

cAMP is a molecule that carries signals inside cells. Receptor activity can change cAMP and other responses. A cellular response does not directly predict a clinical endpoint.

The molecule also includes a fatty-acid modification. This affects binding to albumin, a blood protein. Findings about the defined clinical construct do not certify catalog inventory.

Triple Receptor Activation

Receptor	Natural Hormone	Primary Effects	Retatrutide Potency
GLP-1R	Glucagon-like Peptide-1	Appetite suppression, delayed gastric emptying, insulin secretion, cardiovascular protection	Lower than native GLP-1
GIPR	Glucose-dependent Insulinotropic Polypeptide	Insulin sensitization, fat metabolism, lipid clearance, bone preservation	Higher than native GIP
GCGR	Glucagon	Thermogenic energy expenditure, hepatic fat oxidation, lipolysis, glycogen mobilization	Lower than native glucagon

What does the evidence show?

The TRIUMPH program studies several metabolic outcomes. The table retains the source profile’s trial figures and status descriptions. Time-sensitive statuses should be checked against the current trial record.

The phase 2 paper and sponsor-reported results should be read separately. Population and endpoint definitions matter. Numerical differences between unrelated trials do not establish superiority.

TRIUMPH Clinical Trial Program

Trial	Population	Endpoints	Status
TRIUMPH-1	Obesity/overweight + OSA and/or OA basket	Weight management + complication resolution	Ongoing — 2026 readout
TRIUMPH-2	Obesity/overweight + OSA and/or OA basket	Weight management + complication resolution	Ongoing — 2026 readout
TRIUMPH-3	Obesity/overweight + cardiovascular disease	Weight + CV outcomes	Ongoing — 2026 readout
TRIUMPH-4	Obesity/overweight + knee osteoarthritis	Weight + pain + physical function	Completed — Dec 2025 ✓
Phase 3 T2D	Type 2 diabetes	HbA1c + weight reduction	Ongoing — 2026 readout
Phase 3 MASLD	Metabolic liver disease (fatty liver)	Liver fat + fibrosis	Ongoing — 2026 readout
Phase 3 Chronic Low Back Pain	Obesity + chronic back pain	Pain + weight + function	Ongoing — 2026 readout
Phase 3 Maintenance	Maintenance dosing (4mg)	Weight maintenance post-loss	Ongoing — 2026 readout

Key Results to Date

Phase 2 (NEJM, 2023)

24.2% mean body weight reduction at 48 weeks with the 12mg dose — the highest single-agent weight loss ever reported in a randomized controlled trial at that time. 338 participants across 7 dose groups vs. placebo.

TRIUMPH-4 (Dec 2025)

28.7% weight loss (71.2 lbs average) at 68 weeks with 12mg dose. Pain reduction of 4.5 points on WOMAC scale. 14.1% of patients on 9mg were completely free of knee pain. Systolic blood pressure reduced by 14.0 mmHg. Significant reductions in non-HDL cholesterol, triglycerides, and hs-CRP.

Meta-analysis (2025)

Pooled analysis of 878 patients across 3 RCTs showed significant reductions in body weight (−14.33%), BMI (−5.38), waist circumference (−10.51 cm), and fasting plasma glucose.

Retatrutide vs. Semaglutide vs. Tirzepatide

Semaglutide activates GLP-1 receptors. Tirzepatide activates GLP-1 and GIP receptors. Retatrutide adds glucagon receptor activity.

More receptor targets do not automatically mean a better treatment. The table contains results from different trials, not one direct comparison. A direct study is needed to establish a comparative outcome.

Property	Semaglutide	Tirzepatide	Retatrutide
Receptor Targets	GLP-1 only	GLP-1 + GIP	GLP-1 + GIP + Glucagon
Generation	2nd gen single-agonist	1st gen dual-agonist	1st gen triple-agonist
Max Weight Loss	~16.9% (STEP trials)	~22.5% (SURMOUNT)	~28.7% (TRIUMPH-4)
Thermogenesis	Minimal	Moderate (via GIP)	Significant (via glucagon)
Liver Fat Effect	Moderate reduction	Strong reduction	Strongest (glucagon-driven)
CV Risk Markers	SELECT trial positive	SURPASS-CVOT ongoing	Significant BP/lipid reduction
FDA Status	Approved (2021)	Approved (2022)	Investigational (~2027)
Brand Names	Ozempic / Wegovy	Mounjaro / Zepbound	None yet
Manufacturer	Novo Nordisk	Eli Lilly	Eli Lilly

What are the limits of the safety evidence?

Trials report digestive adverse events such as nausea, diarrhea and vomiting. The pattern must be read with the specific study conditions. It does not establish that a research vial is safe.

Glucagon signaling raises additional metabolic questions. The balance among the three receptor responses remains part of the research. Long-term conclusions require suitable follow-up.

Common (>10%): Nausea, diarrhea, decreased appetite, vomiting, constipation

Moderate (5-10%): Dyspepsia, abdominal pain, injection site reactions

Metabolic: Study-specific safety observations do not establish a personal-use protocol. Read the original source and its limitations.

Monitoring: Study-specific safety observations do not establish a personal-use protocol. Read the original source and its limitations.

What questions remain for future research?

Multi-receptor compounds are an active area of metabolic research. Other candidates use different combinations and molecular structures. A shared target name does not make them equivalent.

Future work can test how receptor balance relates to clinical outcomes. Liver-related hypotheses need appropriate trials. This page does not present experimental materials as established treatments.

Frequently Asked Questions

What is retatrutide?

How does retatrutide differ from Ozempic or Mounjaro?

Ozempic (semaglutide) targets only the GLP-1 receptor. Mounjaro (tirzepatide) targets GLP-1 + GIP receptors. Retatrutide targets all three: GLP-1 + GIP + Glucagon. The addition of glucagon agonism drives increased energy expenditure and liver fat oxidation — effects that the incretin-only compounds do not produce.

What are retatrutide's clinical trial results?

In the Phase 3 TRIUMPH-4 trial (December 2025), mean weight fell 28.7% (71.2 lbs) at 68 weeks. Participants with knee osteoarthritis also reported significant pain relief. Earlier Phase 2 data showed 24.2% weight loss at 48 weeks. Seven additional Phase 3 readouts are expected in 2026.

Is retatrutide FDA-approved?

No. Retatrutide is an investigational compound currently in Phase 3 clinical trials. FDA approval is projected around 2027, contingent on the completion and review of the TRIUMPH program results. It is not currently available as a prescription medication.

What is retatrutide's molecular structure?

Retatrutide is a 39-amino acid synthetic peptide conjugated to a C20 fatty diacid moiety that extends its plasma half-life by promoting albumin binding. It is more potent than native GIP at the GIP receptor, while exhibiting calibrated lower activity at GLP-1 and glucagon receptors.

What conditions is retatrutide being studied for?

The TRIUMPH program includes 8 Phase 3 trials. They cover obesity, type 2 diabetes, knee osteoarthritis, sleep apnea and chronic low back pain. Others study cardiovascular outcomes, metabolic liver disease (MASLD/NASH) and weight maintenance.

What are the side effects of retatrutide?

The most common side effects reported in trials are gastrointestinal: nausea, diarrhea, decreased appetite, vomiting, and constipation. These are generally mild to moderate and tend to decrease over time. Dose titration strategies help minimize GI impact.

How much does retatrutide cost?

As an investigational compound not yet approved or commercially available, retatrutide does not have a market price. For research purposes, pricing varies by supplier, purity grade, and quantity. Check PeptidesDirect product listings for current research-grade availability.

References

[1] Coskun T, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist. Cell Metab. 2022;34(9):1234-1247.
[2] Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. NEJM. 2023;389:514-526.
[3] Eli Lilly. TRIUMPH-4 Phase 3 Topline Results. Press Release, December 11, 2025.
[4] Giblin K, et al. Retatrutide for the treatment of obesity, OSA and knee OA: TRIUMPH program design. Diabetes Obes Metab. 2026;28(1):83-93.
[5] Urva S, et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in T2D. Lancet. 2022;400:1869-1881.
[6] GlobalData. Retatrutide Sales Forecast: $15.6B by 2031. December 2025.