What Is Retatrutide? The Triple Agonist Peptide Everyone's Talking About
- Durham Peptides
- Mar 23
- 3 min read
Updated: Apr 5
If semaglutide was the first wave and tirzepatide was the second, retatrutide is shaping up to be the third — and potentially the most significant — advancement in incretin-based peptide research. Retatrutide is a synthetic peptide that simultaneously activates three receptors: GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon. This triple-agonist mechanism makes it the first compound of its kind to reach advanced clinical trials.
Why Three Receptors Matter
To understand why retatrutide has generated so much excitement in research circles, it helps to understand the progression of incretin-based compounds.
Semaglutide activates one receptor — GLP-1. This single mechanism produced significant results in clinical trials related to metabolic function and body composition, leading to massive public interest and widespread media coverage.
Tirzepatide added a second receptor — GIP — on top of GLP-1. This dual-agonist approach was studied in the SURPASS clinical trial program and demonstrated effects that exceeded semaglutide in head-to-head comparisons across multiple endpoints.
Retatrutide adds a third receptor — glucagon. The glucagon receptor is particularly interesting to researchers because glucagon is known to be involved in thermogenesis and energy expenditure pathways. While GLP-1 and GIP primarily affect appetite signaling and insulin dynamics, glucagon receptor activation is theorized to add a distinct metabolic component that the other two receptors do not engage.
This is why retatrutide is sometimes informally referred to as "GLP-3" in online communities — not because it activates the GLP-3 receptor (which does not exist as a named target), but because it represents the third generation of this class of compounds.
What Does the Research Show?
The landmark study on retatrutide was a Phase 2 clinical trial published in the New England Journal of Medicine in August 2023. The trial enrolled 338 adults and tested multiple dose levels over 48 weeks. The results were striking — at the highest dose (12mg), participants experienced a mean body weight reduction of 24.2% at 48 weeks. At the 8mg dose, the reduction was 22.8%.
To put these numbers in context, no other Phase 2 or Phase 3 trial of a weekly GLP-1 or GIP/GLP-1 agonist had previously reported reductions of this magnitude. Published data for semaglutide at its highest studied doses showed approximately 15-17% reductions, and tirzepatide showed approximately 20-21%.
Perhaps most notably, the weight reduction curves in the retatrutide trial had not yet plateaued at 48 weeks — meaning the full potential effect of the compound may not have been captured within the study duration.
A separate substudy examined retatrutide's effects on liver fat in participants with metabolic dysfunction-associated steatotic liver disease (MASLD). At the 8mg and 12mg doses, liver fat was reduced by over 80% from baseline, with more than 85% of participants achieving resolution of steatosis (defined as less than 5% total liver fat content).
Phase 3 clinical trials for retatrutide began in late 2023 and are ongoing.
Molecular Profile
Retatrutide is a single peptide conjugated to a fatty diacid moiety, similar to the structural approach used in semaglutide and tirzepatide for albumin binding and extended half-life. It has a half-life of approximately 6 days, enabling once-weekly administration in research protocols. Its CAS number is 2381089-83-2.
How It Compares
For researchers studying the incretin class, Durham Peptides carries the full progression: semaglutide (GLP-1 mono-agonist, 10mg), tirzepatide (GIP/GLP-1 dual agonist, 10mg), and retatrutide (GIP/GLP-1/glucagon triple agonist, 10mg). All three are Janoshik tested with independently verifiable COAs, 100% vegan, and ship same-day from Canada.
Selected Research References
Jastreboff AM, et al. "Triple-hormone-receptor agonist retatrutide for obesity — A Phase 2 Trial." N Engl J Med. 2023. PMID: 37366315
Rosenstock J, et al. "Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes." Lancet. 2023. PMID: 37385280
All products mentioned in this article are sold by Durham Peptides for research and laboratory use only. They are not intended for human or animal consumption, diagnosis, treatment, cure, or prevention of any disease.
