Retatrutide vs Tirzepatide
Retatrutide (Triple GIP/GLP-1/glucagon receptor agonist) and Tirzepatide (Dual GIP/GLP-1 receptor agonist) are documented as co-studied in the PeptiDex library. This page puts the two entries side by side on class, molecular weight, half-life, origin, mechanism and studied research areas — every value taken from the entry it belongs to.
Why these two are co-studied
Cross-referenced for research context — not a usage or combination recommendation.
At a glance
| Attribute | Retatrutide | Tirzepatide |
|---|---|---|
| Compound class | Triple GIP/GLP-1/glucagon receptor agonist | Dual GIP/GLP-1 receptor agonist |
| Research category | GLP-1 Family | GLP-1 Family |
| Length (amino acids) | 39 amino acids | 39 amino acids |
| Molecular weight | ~4731 g/mol | 4813.5 g/mol |
| Half-life | ~6 days | ~5 days |
| Origin | An investigational peptide developed by Eli Lilly as a single molecule targeting three receptors: GIP, GLP-1, and glucagon. It has been evaluated in clinical trials in the 2020s. | Developed by Eli Lilly as the first approved dual agonist targeting both the GIP and GLP-1 receptors. It received first FDA approval in 2022. |
“Not documented” means the PeptiDex entry records no value for that field. Nothing on this page is estimated, and no figure is carried over from one compound to the other.
How Retatrutide works
Retatrutide is a synthetic peptide agonist designed to activate the GIP, GLP-1, and glucagon receptors simultaneously. GIP and GLP-1 agonism support glucose-dependent insulin secretion, glucagon suppression, delayed gastric emptying, and appetite reduction, while glucagon-receptor agonism is proposed to increase energy expenditure. The combined activity is being studied for its effects on body weight and metabolic parameters.
How Tirzepatide works
Tirzepatide is a synthetic peptide that activates both the glucose-dependent insulinotropic polypeptide (GIP) receptor and the GLP-1 receptor. Combined agonism enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite and food intake. It carries a C20 fatty-diacid moiety enabling albumin binding and a prolonged half-life supporting once-weekly administration.
Mechanistic descriptions reflect published research-literature understanding and are quoted from each compound's own entry. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
Where each one appears in the literature
The research contexts each entry documents. Listing a research area is not a claim of efficacy or a therapeutic indication, and the two lists are not scored against each other.
Described in identical terms for both
Retatrutide
Tirzepatide
What sets each apart
Retatrutide
Retatrutide differs from tirzepatide and semaglutide by adding a third target, the glucagon receptor, making it a triple agonist rather than a single or dual agonist.
Tirzepatide
Tirzepatide differs from semaglutide and other single GLP-1 agonists by simultaneously engaging the GIP receptor, a mechanism proposed to contribute to its metabolic effects.
Frequently asked questions
How does retatrutide differ from tirzepatide?
Tirzepatide is a dual GLP-1/GIP agonist, while retatrutide adds a third arm — glucagon-receptor agonism. In the reported obesity models this triple mechanism is associated with larger mean body-weight reductions at the higher doses. Retatrutide is earlier in the clinical pipeline and less extensively characterized than tirzepatide.
What is retatrutide and what makes it a 'triple agonist'?
Retatrutide (LY3437943) is a single-molecule triple agonist that activates the GLP-1, GIP, and glucagon receptors. The added glucagon-receptor activity — associated in research with increased energy expenditure — is what distinguishes it from GLP-1 mono-agonists and GLP-1/GIP dual agonists. It is studied in models of obesity and metabolic regulation.
What is retatrutide's half-life and how does it shape study design?
Retatrutide has a reported half-life of approximately 6 days, which supports once-weekly administration in the published trials. Steady-state levels are generally reached after about 4-5 weeks of weekly dosing at a given dose, so protocols use a multi-week escalation before any maintenance readout. The long half-life implies a multi-week washout after stopping.
What is tirzepatide and how is its mechanism different from a GLP-1 mono-agonist?
Tirzepatide is a dual agonist that activates both the GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptors from a single synthetic peptide backbone with a C20 fatty-diacid for half-life extension. The added GIP activity is the key distinction from GLP-1-only agonists like semaglutide. It is studied in models of glucose handling, appetite, and body-weight change.
What is tirzepatide's half-life and what does it imply for study design?
Tirzepatide has a reported half-life of about 5 days (~117 hours), supporting once-weekly administration in the literature. Steady state is generally reached after about 4 weeks at a given dose, so protocols include a multi-week escalation before maintenance-phase readouts. The multi-day half-life also means a washout of several weeks after discontinuation.
How is tirzepatide dose-escalated in research protocols?
Published protocols escalate weekly from 2.5 mg upward through 5, 7.5, 10, 12.5 and up to 15 mg once weekly, with each step commonly held about 4 weeks. As with other incretin agonists, escalation is used to limit gastrointestinal tolerability issues. These are reference figures for research context only, not human dosing guidance.
Answers are the ones published on each compound's own PeptiDex entry. They are educational summaries of research-literature context and are not medical advice.