Retatrutide remains in Phase 3 TRIUMPH clinical trials as of May 2026. An NDA filing is expected Q4 2026, with potential FDA approval in 2027–2028. Here's what the timeline means for researchers right now.
Published May 29, 2026·Updated weekly·8 min read
Current status: Not FDA approved · Phase 3 ongoing · Available for research use
28.7%
Weight loss at 68 wks — TRIUMPH-4 Phase 3 (Dec 2025)
Q4 '26
Expected NDA filing by Eli Lilly
2027–28
Earliest potential FDA approval
What Is Retatrutide (GLP-3 RT)?
Retatrutide (LY3437943) is an investigational triple receptor agonist developed by Eli Lilly. Unlike Tirzepatide — which targets GLP-1 and GIP — Retatrutide adds a third receptor: the glucagon receptor (GCGR). This triple-agonist profile drives appetite suppression, insulin sensitization, and thermogenic fat oxidation simultaneously.
In the research community it is designated GLP-3 RT, reflecting its triple receptor activity. It is available in lyophilized form for research applications from US-based research peptide vendors.
Current FDA Approval Status
Retatrutide is not FDA approved for any indication as of May 29, 2026. No New Drug Application has been submitted. Eli Lilly's Q4 2025 earnings guidance indicated NDA filing in late 2026 pending TRIUMPH Phase 3 program completion. After NDA submission, the FDA's standard review is 10–12 months.
Milestone
Status
Timing
Phase 2 TRIUMPH-1
Complete
2023 (NEJM)
Phase 3 TRIUMPH-4
Data Released
Dec 2025
Phase 3 TRIUMPH-1
Data Released
May 2026
TRANSCEND-T2D-1
Endpoints Met
Mar 2026
NDA Submission
Expected
Q4 2026
FDA Review
Pending NDA
2027
FDA Approval
Not Approved
2027–2028 est.
Phase 3 TRIUMPH Data
Eli Lilly's TRIUMPH Phase 3 program encompasses multiple trials across obesity, type 2 diabetes, NASH, and cardiovascular outcomes. The weight loss results are the highest ever reported in an obesity drug trial.
Trial
Result
Status
TRIUMPH-4 Obesity, Phase 3
–28.7% body weight at 68 wks
Released Dec 2025
TRIUMPH-1 Obesity, Phase 3
–28.3% body weight at 68 wks
Released May 2026
TRANSCEND-T2D-1 Type 2 Diabetes
Met HbA1c primary endpoints
Released Mar 2026
TRIUMPH-NASH Hepatic steatosis
Ongoing
In Progress
TRIUMPH-CV Cardiovascular outcomes
Ongoing
In Progress
Historical context
The 28.7% mean weight loss in TRIUMPH-4 is the highest ever recorded in any obesity clinical trial. Tirzepatide (Zepbound) achieved ~22.5% in SURMOUNT-1. Semaglutide (Wegovy) achieved ~14.9% in STEP 1. Retatrutide is the first pharmacologic agent to approach surgical-level weight reduction in a randomized trial.
Approval Timeline
2023
Phase 2 TRIUMPH-1 — NEJM Publication
24.2% weight loss at 48 weeks — highest Phase 2 result ever recorded for an anti-obesity agent. Rapid advancement to Phase 3.
December 2025
TRIUMPH-4 Phase 3 Readout
28.7% mean weight loss at 68 weeks. All primary and secondary endpoints met. Highest weight reduction ever recorded in an obesity trial of any phase.
28.3% weight loss confirmed. No NDA filed. Retatrutide available for research use from US vendors.
Q4 2026
Expected NDA Submission
Eli Lilly expected to file New Drug Application with the FDA after TRIUMPH program completion. Standard FDA review: 10–12 months.
2027–2028
Potential FDA Approval & Commercial Launch
If NDA filed Q4 2026 and review proceeds on standard timeline, approval could arrive late 2027. Prescription availability (Mounjaro/Zepbound model) likely Q1 2028.
Research Access Right Now
Research Peptide Vendors
US-based research peptide vendors sell Retatrutide under a research-use-only (RUO) framework — products labeled strictly for in-vitro laboratory research, not for human or animal use. This framework operates separately from FDA drug approval and compounding pharmacy rules. Retatrutide has been available through this channel throughout the Phase 3 trial period.
Available for Research
Evo Peptides carries GLP-3 RT (Retatrutide) at ≥99% purity with third-party COA documentation on every batch. Same-day shipping from Wisconsin before 3:00 PM CST.
Clinical Trial Enrollment
Eli Lilly's TRIUMPH Phase 3 program has multiple active trials with ongoing enrollment. Participants receive the investigational compound under medical supervision at no cost. Search "LY3437943" on ClinicalTrials.gov for current open studies.
Research Use Disclaimer — All Evo Peptides products are intended for research use only and are not for human consumption. This article is informational and does not constitute medical or regulatory advice. Regulatory status can change; verify current FDA guidance at fda.gov.
Frequently Asked Questions
Is Retatrutide FDA approved in 2026?
No. Retatrutide is not FDA approved as of May 2026. It remains in Phase 3 TRIUMPH clinical trials. An NDA submission is expected Q4 2026, with potential approval in 2027–2028. No regulatory body worldwide has approved it for any indication.
When will Retatrutide be FDA approved?
Based on Eli Lilly's Q4 2025 guidance, NDA filing is expected late 2026. FDA standard review takes 10–12 months, placing potential approval at late 2027. Commercial availability would likely follow in Q1 2028. These are estimates subject to trial outcomes and FDA decisions.
Can researchers buy Retatrutide right now?
Yes. Retatrutide (GLP-3 RT) is available from US-based research peptide vendors for laboratory research use. This is separate from FDA drug approval rules. Evo Peptides carries GLP-3 RT at ≥99% purity with COA documentation.
How does Retatrutide differ from Tirzepatide?
Tirzepatide (Mounjaro/Zepbound) is a dual GLP-1/GIP agonist and is FDA approved. Retatrutide adds the glucagon receptor, making it a triple agonist. Phase 3 data shows Retatrutide achieves ~28.7% weight loss vs. Tirzepatide's ~22.5% — attributed to the additional glucagon-driven thermogenesis.
What will Retatrutide be called when approved?
No brand name has been officially announced as of May 2026. Eli Lilly has not confirmed a commercial name for Retatrutide. Speculation exists but nothing is official.
Evo Peptides
Research GLP-3 RT Today
≥99% purity, third-party COA verified. Same-day shipping from Wisconsin.