Retatrutide vs cagrilintide: what are the differences?
Retatrutide (Eli Lilly) and cagrilintide (Novo Nordisk) are two peptides being studied for obesity, administered once a week in clinical trials. However, they do not work in the same way at all: one mimics three intestinal and pancreatic hormones, the other amylin. Here are their differences, supported by published data.
Retatrutide R3 10 mg – €59.90Cagrilintide 5 mg – €69.90
The essentials
- Retatrutide: triple receptor agonistGIP, GLP-1 and glucagonUp to −24.2% average weight loss at 48 weeks in phase 2.
- Cagrilintide: a long-acting analogue of amylin, a satiety hormone. Up to −10.8% at 26 weeks alone in phase 2, and studied primarily in combination with semaglutide (CagriSema).
- Both have a half-life of approximately one week and areadministered once a weekin the trials.
- None of them are authorized as a drug to date; they are research peptides.
Comparative table
| Retatrutide | Cagrilintide | |
|---|---|---|
| Laboratory | Eli Lilly (LY3437943) | Novo Nordisk (AM833) |
| Class | GIP/GLP-1/glucagon triple agonist | Amylin analogue (amylin and calcitonin agonist) |
| Structure | 39-amino-acid peptide, acylated | Acyl analogue of amylin (37 amino acids) |
| Half-life | approximately 6 days | approximately 7 days |
| Reference trial | Phase 2, NEJM 2023: up to −24.2% at 48 weeks | Phase 2, Lancet 2021: up to −10.8% at 26 weeks |
| Development | Alone (TRIUMPH program) | Especially in combination with semaglutide (CagriSema, REDEFINE program) |
| Status | Not authorized; FDA submission expected in Q1 2027 | Not authorized alone |
| At MyPeptide | 10 mg at €59.90, 20 mg at €99.90 | 5 mg at €69.90 |
Retatrutide: one molecule, three receptors
Retatrutide activates receptors for GLP-1 (satiety, insulin secretion), GIP (another incretin, affecting fat metabolism), and glucagon (energy expenditure, liver fat mobilization). It is this third target that distinguishes it from tirzepatide (GIP + GLP-1) and semaglutide (GLP-1 alone). Its fatty acid chain binds to albumin, resulting in a half-life of approximately 6 days. For further information: R3 and weight loss.
Cagrilintide: the amylin pathway
Amylin is a hormone secreted by the pancreas along with insulin after meals. It acts on the brainstem to increase satiety, slows gastric emptying, and inhibits glucagon secretion after eating. Natural amylin is unstable and lasts only a few minutes; cagrilintide is an acylated version that acts for about a week and also activates calcitonin receptors. It does not act on the GLP-1 receptor: it uses a different, complementary pathway. Our detailed guide: cagrilintide, the amylin analog.
What the published studies say
| Trial | Duration | Average weight loss | Placebo |
|---|---|---|---|
| Retatrutide, phase 2 (Jastreboff et al., NEJM 2023) | 48 weeks | up to -24.2% | -2.1% |
| Cagrilintide alone, phase 2 (Lau et al., Lancet 2021) | 26 weeks | up to -10.8% | -3.0% |
| Cagrilintide alone, arm of REDEFINE 1 (Garvey et al., NEJM 2025) | 68 weeks | -11.8% | -3.0% |
| CagriSema(cagrilintide + semaglutide), REDEFINE 1 | 68 weeks | -20.4% | -3.0% |
These figures come from different trials, with different durations and populations: they do not constitute a direct comparison. No trial has compared retatrutide to cagrilintide. In both cases, the most frequently reported adverse effects aredigestives(nausea, diarrhea, vomiting), especially at the beginning of treatment.
Should we combine them in research?
Amylin's appeal lies precisely in its different pathway: when combined with a GLP-1 agonist, it adds its effect rather than doubling it. This is the rationale behind CagriSema, which outperformed semaglutide and cagrilintide taken separately in REDEFINE 1. The retatrutide + cagrilintide combination is therefore generating interest, but no published clinical trial has evaluated it to date. We are not providing any protocols.
Regulatory status
Neither retatrutide nor cagrilintide is authorized as a drug in France or the European Union. For retatrutide, Eli Lilly plans to submit an application to the FDA in the first quarter of 2027 (seeIs R3 a medicine?Cagrilintide is primarily developed within the CagriSema association. Outside of clinical trials, both are sold only as research peptides.
Formats and prices
| Product | Content | Price |
|---|---|---|
| Retatrutide R3 10 mg | 1 lyophilized vial 10 mg | 59,90 € |
| Retatrutide R3 20 mg | 1 lyophilized vial 20 mg | 99,90 € |
| Cagrilintide 5 mg | 1 lyophilized vial 5 mg | 69,90 € |
| R10 Pack | Retatrutide 10 mg + reconstitution kit | 69,90 € |
| Reconstitution Pack | Bacteriostatic water 3 ml, syringes, gloves, swabs (peptide-free) | 14,90 € |
To prepare the two bottles: our reconstitution calculator gives the concentration according to the volume of water.
Retatrutide tested in a blind trial by Janoshik (7 published reports). Shipping €10 for the entire order, shipped from the European Union.
Retatrutide R3 10 mg – €59.90Cagrilintide 5 mg – €69.90
Frequently Asked Questions
What is the difference between retatrutide and cagrilintide?
Retatrutide activates three receptors (GIP, GLP-1 and glucagon); cagrilintide mimics amylin, a satiety hormone, and does not act on the GLP-1 receptor. The former is developed by Eli Lilly, the latter by Novo Nordisk.
Is cagrilintide a GLP-1?
No. It is an amylin analogue, which activates amylin and calcitonin receptors. That is why it is being studied in combination with a GLP-1 agonist, semaglutide (CagriSema).
Which one resulted in the greatest weight loss in the trials?
Retatrutide: up to −24.2% at 48 weeks in phase 2, compared to −10.8% at 26 weeks and −11.8% at 68 weeks for cagrilintide alone. These trials are not directly comparable, and no trial has compared them.
Can retatrutide and cagrilintide be combined?
No published clinical trials have evaluated this combination. The idea originated with CagriSema (cagrilintide + semaglutide), which is more effective than either drug alone. We are not providing any protocol details.
What is the half-life of retatrutide and cagrilintide?
Approximately 6 days for retatrutide and approximately 7 days for cagrilintide, which explains their weekly administration in the trials. Our half-life calculator shows the week-by-week decrease.
Sources: Jastreboff A.M. et al., N Engl J Med 2023; Lau D.C.W. et al., Lancet 2021; Garvey W.T. et al., N Engl J Med 2025 (REDEFINE 1); Coskun T. et al., Cell Metabolism 2022. MyPeptide products are intended exclusively for scientific laboratory research.