Research profile
INN retatrutide
Research topics, not use categories.
Registered trials5, listed apart from the publications
Content reviewed October 6, 2026
View material (GLP-3 product page)GLP-3 is the name this store uses for retatrutide, a synthetic peptide of 39 amino acids with a fatty side chain attached. It is a compound under development by a pharmaceutical company (called the developer here) and is not an approved medicine.
This profile summarizes only two publications. One is a laboratory study in strips of human heart tissue (right atrium) obtained during heart surgery, in which the compound increased the force with which the tissue contracted. The other is a 48-week randomized trial in 338 adults, funded by the developer and controlled with a placebo (an inactive comparison); its main results are not summarized here, but the most common adverse events were gastrointestinal, such as nausea, and heart rate rose during the first 24 weeks.
The published human research is larger than this profile: other trials funded by the developer have been published, including, in September 2026, a peer-reviewed report of one of its large registered trials (TRIUMPH-1). Their results are not summarized here. Registered trials are listed separately, by their registry entries.
The most important limitation is that the heart-tissue result comes from isolated tissue in a laboratory bath and does not show what happens in the intact heart, and that every published human trial located was funded by the developer.
Selected observations from the publications listed in this profile, which are a curated subset of the literature, not all of it. Each one names the system it was observed in and links its source; a finding in cells or animals is not a result in people.
In strips of human right atrium obtained during cardiac surgery, retatrutide increased the force of contraction in a concentration- and time-dependent manner, more strongly when the PDE3 inhibitor cilostamide was present; antagonists at its three receptors reduced the effect, while the beta-blocker propranolol did not.
(Neumann et al. · 2026 · PMID 40613938 (opens PubMed in a new tab))
Limits: Isolated tissue from patients taking cardiac medication; the intact heart, the sinus node and ventricular tissue were not studied.
In a 48-week randomized, double-blind, placebo-controlled trial in 338 adults funded by the developer, the most common adverse events were gastrointestinal and more frequent at higher exposure, and heart rate rose with exposure, peaking at 24 weeks and declining thereafter.
(Controlled study in humans · 2023 · PMID 37366315 (opens PubMed in a new tab))
Limits: The trial's primary and secondary endpoints are not summarized in this profile.
Human, animal and in vitro evidence are kept apart: where a result was observed decides what it can say. In vitro covers cultured cells and tissue studied outside the body. Reviews are listed under Publications; registered trials are listed below, apart from the publications.
The human trial listed in this profile is a randomized, double-blind, placebo-controlled trial of 48 weeks in 338 adults, funded by the developer and published in 2023; its primary and secondary endpoints are not summarized in this profile. In it, the most frequently reported adverse events were gastrointestinal (nausea, diarrhea, vomiting and constipation), were mostly mild to moderate and occurred more often in higher-exposure groups, and heart rate increased with exposure, peaking at 24 weeks and declining thereafter. Other published human trials exist and are not listed here, among them the peer-reviewed report of the registered trial TRIUMPH-1, published on September 29, 2026. All the published human trials located were funded by the developer, with company employees among the authors, and no independent human trials were located. Registered trials are listed separately, by their registry entries: TRIUMPH-1, whose results have been published in peer-reviewed form; three further large placebo-controlled trials, whose topline results the developer has announced but which had not been published in peer-reviewed form at the review date; and the registry entry of the listed trial. The developer's announcements are not peer-reviewed and are not summarized in this profile.
Listed publications at this level
Animal studies are not summarized in this profile. The indexed literature includes rodent studies from the developer's discovery work and from independent groups. Findings in rodents do not allow inferences about effects in humans.
No animal study is listed in this profile.
The in vitro evidence summarized in this profile is one study by an academic group without affiliation to the developer, in right atrial preparations obtained from 29 patients during cardiac surgery: retatrutide increased force of contraction, an effect that was reduced by selective antagonists of each of its three receptors and persisted under β-adrenergic receptor blockade. The developer's characterization of the compound in cell systems and structural or ligand-binding studies are not summarized. Cell systems and isolated tissue do not reproduce the pharmacology of a whole organism.
Listed publications at this level
Registry entries, listed apart from the publications and not counted with them. Each links to its ClinicalTrials.gov record and shows only the registered phase, design, enrollment and status, and where its results stand. Results announced by a sponsor are marked as not peer-reviewed and are not summarized here.
NCT05929066 (opens the ClinicalTrials.gov record in a new tab)
Results peer-reviewedDOI 10.1056/NEJMoa2604169 (opens the publisher record in a new tab)Publication not listed or summarized in this profile
NCT05929079 (opens the ClinicalTrials.gov record in a new tab)
Sponsor topline reported July 2026, not peer-reviewed
NCT05882045 (opens the ClinicalTrials.gov record in a new tab)
Sponsor topline reported July 2026, not peer-reviewed
NCT05931367 (opens the ClinicalTrials.gov record in a new tab)
Sponsor topline reported December 2025, not peer-reviewed
ClinicalTrials.gov record of NCT04881760 (opens in a new tab)
Results peer-reviewedPMID 37366315 (opens PubMed in a new tab)
The technical layer: molecular identity, the mechanisms investigated with the evidence level at which each was observed, and the limits of the evidence. The plain-English summary is under Overview.
Retatrutide is a synthetic peptide of 39 amino acid residues. It incorporates non-proteinogenic residues and a side chain bearing a fatty diacid (see identifiers). It is a compound under study and not an approved medicine.
This profile lists one in vitro study, in isolated human atrial tissue, and one peer-reviewed controlled human trial whose endpoints are not summarized; other in vitro studies, animal studies and other published human trials are not summarized. Registered trials are listed separately, by their registry entries only. This profile presents published scientific literature as research context and contains no directions for use.
Mechanistic hypotheses and observations as they were studied. The evidence level shows where each one was observed; none has been shown in people.
In right atrial preparations obtained during cardiac surgery, an academic group without affiliation to the developer observed that retatrutide increased force of contraction in a concentration- and time-dependent manner, with a larger effect in the presence of a phosphodiesterase-3 inhibitor. The effect was reduced by selective antagonists of its three receptors but not by propranolol, which the authors interpret as a cAMP-mediated action through those receptors rather than through β-adrenergic receptors. The study did not examine the sinus node, so it does not show whether the heart-rate increase reported in human trials is a direct or an indirect effect.
Each publication is identified by its PubMed ID or DOI and grouped by evidence level. Each heading is our own description of what was studied. Titles, authors and journals are reproduced exactly as published; when the published wording of one of them falls outside our content rules, it is not shown here, and the record links to PubMed, where it can be read in full.
The New England Journal of Medicine2023PMID 37366315 (opens PubMed in a new tab)Full record on PubMedDOI 10.1056/NEJMoa2301972 (opens the publisher record in a new tab)
Registry recordNCT04881760 (opens the ClinicalTrials.gov record in a new tab)
Trial funded by the developer, with company employees among the authors, conducted with material supplied by the developer. Its primary and secondary endpoints are not summarized in this profile; they are described in the original record. The authors report that the most common adverse events were gastrointestinal, occurred more often in higher-exposure groups and were mostly mild to moderate, and that heart rate increased with exposure, peaking at 24 weeks and declining thereafter.
Measured endpoints
Limitations: Funded by the developer, with company employees among the authors; 48 weeks; material supplied by the developer within a controlled trial; the participants' characteristics and the trial's endpoints are described in the original record, not in this profile.
“Inotropic effects of retatrutide in isolated human atrial preparations.”
Neumann J, Ahlrep U, Hofmann B, Gergs UNaunyn-Schmiedeberg's Archives of Pharmacology2026PMID 40613938 (opens PubMed in a new tab)DOI 10.1007/s00210-025-04421-3 (opens the publisher record in a new tab)
Study by an academic group without affiliation to the developer. In isolated human right atrial preparations, retatrutide increased force of contraction in a concentration- and time-dependent manner; with the phosphodiesterase-3 inhibitor cilostamide present, the effect was larger and relaxation time shortened. The effect was reduced by selective antagonists of its three receptors and by carbachol, stimulation of adenosine A1 receptors and ryanodine, but not by propranolol; the authors interpret it as a cAMP-mediated action through those receptors rather than through β-adrenergic receptors. The sinus node and ventricular tissue were not examined.
Measured endpoints
Limitations: Isolated atrial tissue from patients undergoing cardiac surgery who were receiving cardiac medication; the sinus node and ventricular tissue were not examined; the study cannot show whether the heart-rate increase reported in human trials is a direct or an indirect effect; the authors consider its clinical relevance uncertain.
For laboratory research use only. Not for human or veterinary use or consumption. Not for diagnostic use. Not evaluated by the U.S. FDA.