Cagrilintide and retatrutide are two of the most discussed investigational weight-loss peptides, and they have almost nothing in common chemically. Cagrilintide, from Novo Nordisk, is a long-acting version of amylin, a satiety hormone made in the pancreas alongside insulin. Retatrutide, from Eli Lilly, is a single molecule built to act on three gut-hormone receptors at once. Both are injected once weekly in their trials; their milligram ranges barely overlap. This page sets out each one's dose record (read 2026-10-05) and the syringe arithmetic. It compares; it recommends neither.
The single-compound records are on the cagrilintide and retatrutide dosage pages. Cagrilintide's pairing with semaglutide, CagriSema, and the trials that set it against tirzepatide are on cagrilintide and GLP-1 stacks; that page covers combinations, this one a comparison.
The two dose records
| Cagrilintide | Retatrutide | |
|---|---|---|
| Developer | Novo Nordisk | Eli Lilly |
| Target | Amylin and calcitonin receptors | GIP + GLP-1 + glucagon receptors |
| Molecular weight | 4,409 (PubChem CID 171397054) | — |
| Doses tested in phase 2 | 0.3, 0.6, 1.2, 2.4, 4.5 mg weekly | 1, 4, 8, 12 mg weekly |
| Phase 2 escalation | up to 6 weeks | 4 and 8 mg arms from 2 or 4 mg; 12 mg from 2 mg |
| Dose in phase 3 | 2.4 mg (alone or with semaglutide 2.4 mg) | 4, 9, 12 mg |
| Highest tested | 4.5 mg | 12 mg |
| Approval | None; CagriSema filed with the FDA in December 2025 (as recorded on the cagrilintide page) | None; Lilly plans to file in Q1 2027 (as recorded on the retatrutide page) |
| Registry, 2026-10-05 | 44 intervention records | 33 intervention records |
The scales are different molecules' scales. Cagrilintide's phase 3 dose, 2.4 mg, sits near retatrutide's 2 mg starting step; retatrutide's lowest phase 3 dose, 4 mg, is near the top of everything cagrilintide was tested at. The milligram figures say nothing about equivalent effect.
What each reported at each dose
| Trial and dose | Weight change | Comparator | Duration |
|---|---|---|---|
| Cagrilintide phase 2, 0.3–4.5 mg | −6.0% to −10.8% | placebo −3.0% | 26 weeks |
| Cagrilintide phase 2, 4.5 mg | −10.8% | liraglutide 3.0 mg −9.0% | 26 weeks |
| Retatrutide phase 2, 4 mg | −17.1% | placebo −2.1% | 48 weeks |
| Retatrutide phase 2, 12 mg | −24.2% | placebo −2.1% | 48 weeks |
| REDEFINE 1, cagrilintide 2.4 mg + semaglutide 2.4 mg | −20.4% | placebo −3.0% | 68 weeks |
| TRIUMPH-1, retatrutide 12 mg | −28.3% | placebo −2.2% | 80 weeks |
Sources: Lau et al. 2021 (cagrilintide phase 2, reported under the trial product estimand, which assumes everyone stayed on treatment); Jastreboff et al. 2023; Garvey et al. 2025; Lilly's release of 2026-05-21 for TRIUMPH-1, as recorded on the retatrutide page. REDEFINE 1 also had a cagrilintide-alone arm at 2.4 mg (302 people), but the published abstract reports only the combination against placebo. So the largest cagrilintide figure on record without semaglutide is the 26-week phase 2 result, and it sits beside a 48-week retatrutide result: different lengths, different estimands, different populations.
Tolerability is reported in different terms too. Lau reports gastrointestinal adverse events in 41% to 63% of people on cagrilintide against 32% on placebo, mostly nausea. Retatrutide's phase 2 paper calls its gastrointestinal events dose-related and "partially mitigated with a lower starting dose (2 mg vs. 4 mg)".
The combination, which exists only in rats
ClinicalTrials.gov held no registration naming cagrilintide and retatrutide together on 2026-10-05; every cagrilintide combination registered is with semaglutide or set against tirzepatide. The one published combination is a University of Copenhagen study in diet-induced obese male rats (Petersen et al., Nature Metabolism, online 2026-09-15). Given daily, the pair produced "dose-dependent reductions in body weight and food intake that exceed both equimolar monotherapies and matched-dose comparator combinations incorporating semaglutide or tirzepatide", and pair-feeding experiments indicated the extra loss was not explained by eating less alone.
Three limits travel with that finding. It is a rodent study, dosed daily rather than weekly, in males only. The authors frame it as support for "five-receptor polypharmacology" and for designing future single molecules, not as a protocol. And their competing-interest statement lists co-founded obesity biotech companies, speaking fees from Novo Nordisk, Novo Nordisk stockholdings in one author's household and counselling fees from Eli Lilly.
The doses in units, research vials
Neither molecule's research-vial form is covered by a label. Units on a U-100 syringe = mg ÷ mg/mL × 100:
| Dose | 2.5 mg/mL | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|---|
| Cagrilintide 0.3 mg | 12 | 6 | 3 | 1.5 |
| Cagrilintide 1.2 mg | 48 | 24 | 12 | 6 |
| Cagrilintide 2.4 mg | 96 | 48 | 24 | 12 |
| Cagrilintide 4.5 mg | 180 ✕ | 90 | 45 | 22.5 |
| Retatrutide 2 mg | 80 | 40 | 20 | 10 |
| Retatrutide 4 mg | 160 ✕ | 80 | 40 | 20 |
| Retatrutide 8 mg | 320 ✕ | 160 ✕ | 80 | 40 |
| Retatrutide 12 mg | 480 ✕ | 240 ✕ | 120 ✕ | 60 |
✕ = more than one 1 mL syringe holds. Cagrilintide research vials in this site's data are labelled 5 and 10 mg, so its 20 mg/mL column is reference arithmetic only. Every cagrilintide dose fits one syringe at 5 mg/mL; retatrutide needs 10 mg/mL or more for its middle doses and 12 mg/mL or more for its top one. The mg to units page sets out the formula; the calculator's cagrilintide and retatrutide settings handle any vial and volume.
What is not established
No trial compares cagrilintide with retatrutide, and none gives them together in people. Neither has a regulator-reviewed dose. Cagrilintide's monotherapy result at its phase 3 dose has not appeared in the abstracts read, and TRIUMPH-1 is known from Lilly's release rather than a paper. The rat combination gives no human dose. Research-market vials under either name have no data of their own. The compounds are covered in Medibact's cagrilintide guide and retatrutide guide. Nothing on this page is an instruction; dose and product belong with a clinician.
Sources and dates
Opened 2026-10-05: PubMed abstracts 34798060 (Lau et al., Lancet 2021), 37366315 (Jastreboff et al., NEJM 2023), 40544433 (Garvey et al., NEJM 2025) and 42744908 (Petersen et al., Nature Metabolism 2026); PubChem record for cagrilintide (CID 171397054); ClinicalTrials.gov intervention searches for cagrilintide, retatrutide and both together. The CagriSema filing and the cagrilintide vial sizes are as recorded on this site's cagrilintide page (2026-09-18); the TRIUMPH figures and Lilly's filing plan as recorded on its retatrutide page from Lilly's releases of 2026-05-21 and 2026-07-23. Unit figures are arithmetic by this site. Corrections go to the contact page.