Survodutide and retatrutide are the two most advanced molecules that add glucagon to the GLP-1 approach. Boehringer Ingelheim's survodutide pairs glucagon with GLP-1; Eli Lilly's retatrutide adds a third receptor, GIP. Both have finished phase 3 obesity trials, neither is approved, and no trial puts them side by side. What can be compared is the dose record each company has published. This page sets the two ladders next to each other (read 2026-10-04) and does the syringe arithmetic. It compares; it recommends neither.
The single-compound records are on the survodutide and retatrutide dosage pages. For the molecules' trial outcomes in a magazine format, GLP1 Ledger's survodutide vs retatrutide covers ground this page does not repeat. Retatrutide set against an amylin analogue rather than a glucagon agonist is on cagrilintide vs retatrutide.
The two dose records
| Survodutide | Retatrutide | |
|---|---|---|
| Developer | Boehringer Ingelheim | Eli Lilly |
| Receptors | Glucagon + GLP-1 | GIP + GLP-1 + glucagon |
| First step | 0.3 mg weekly (phase 2) | 2 mg weekly (phase 3) |
| Step interval | Every 2 weeks in phase 2; lengthened in phase 3 | Every 4 weeks |
| Phase 3 doses | 3.6 mg, 6.0 mg | 4 mg, 9 mg, 12 mg |
| Highest dose tested in obesity phase 2 | 4.8 mg | 12 mg |
| Half-life | Not stated in the abstracts read | About 6 days |
| Approval | None | None; Lilly plans to file in Q1 2027 |
Survodutide's phase 2 escalation, posted week by week on ClinicalTrials.gov (NCT04667377), climbed through 0.3, 0.6, 0.9, 1.2, 1.8, 2.4, 3.3 and 4.2 mg to reach 4.8 mg at week 17. Boehringer's phase 3 design paper says that schedule was lengthened because gastrointestinal events clustered during escalation; the week-by-week phase 3 table is unpublished. Retatrutide's ladder is shorter and coarser: four-weekly steps of 2, 4, 6 and 9 mg on the way to 12 mg, as described in Lilly's 2026 releases.
The two ladders start almost sevenfold apart — 2 mg against 0.3 mg — and end twofold apart, at 12 mg and 6.0 mg. The milligram figures are therefore not on a common scale: survodutide's top phase 3 dose, 6.0 mg, is the step retatrutide passes through on its way from 4 mg to 9 mg.
What each trial reported at each dose
| Trial and dose | Weight change | Placebo | Duration |
|---|---|---|---|
| Survodutide phase 2, 4.8 mg | −14.9% | −2.8% | 46 weeks |
| Retatrutide phase 2, 12 mg | −24.2% | −2.1% | 48 weeks |
| SYNCHRONIZE-1, survodutide 3.6 mg | −12.2% | −5.4% | 76 weeks |
| SYNCHRONIZE-1, survodutide 6.0 mg | −13.0% | −5.4% | 76 weeks |
| TRIUMPH-1, retatrutide 4 mg | −19.0% | −2.2% | 80 weeks |
| TRIUMPH-1, retatrutide 9 mg | −25.9% | −2.2% | 80 weeks |
| TRIUMPH-1, retatrutide 12 mg | −28.3% | −2.2% | 80 weeks |
Survodutide figures are from the published abstracts (PMID 38330987; PMID 42253238); retatrutide's phase 2 figures from the NEJM abstract (PMID 37366315) and its phase 3 figures from Lilly's release of 2026-05-21, which has not yet appeared as a paper. One difference stands out before any comparison: the placebo groups. SYNCHRONIZE-1's placebo arm lost 5.4%, more than twice the 2.2% of TRIUMPH-1's, and the NEJM paper analysed everyone randomised whether or not they stayed on treatment. Different placebo responses and different analyses move the drug figures too, which is why trial results from separate programmes are not a head-to-head result.
Tolerability is reported differently as well. SYNCHRONIZE-1 gives gastrointestinal events in 80.9% (3.6 mg) and 89.7% (6.0 mg) of participants against 47.9% on placebo. Lilly's TRIUMPH-1 release gives discontinuations for adverse events — 4.1%, 6.9% and 11.3% on 4, 9 and 12 mg against 4.9% on placebo — rather than event rates, so the two figures do not line up.
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 | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|
| Survodutide 0.3 mg (first step) | 6 units | 3 units | 1.5 units |
| Survodutide 3.6 mg | 72 units | 36 units | 18 units |
| Survodutide 6.0 mg | 120 units ✕ | 60 units | 30 units |
| Retatrutide 2 mg (first step) | 40 units | 20 units | 10 units |
| Retatrutide 4 mg | 80 units | 40 units | 20 units |
| Retatrutide 9 mg | 180 units ✕ | 90 units | 45 units |
| Retatrutide 12 mg | 240 units ✕ | 120 units ✕ | 60 units |
✕ = more than one 1 mL syringe holds. 20 mg/mL is a 20 mg vial with 1 mL; survodutide vials in this site's data come in 5, 10 and 15 mg, so for survodutide that column is reference arithmetic only. The two molecules sit at opposite ends of the syringe: survodutide's first step at 10 mg/mL is 3 units, where a 1 mL barrel reads least precisely, while retatrutide's top dose overflows one syringe at any concentration below 12 mg/mL. The mg to units page sets out the formula; the calculator's survodutide and retatrutide settings handle any vial and volume.
What is not established
No trial compares survodutide with retatrutide. Neither has a regulator-reviewed dose. Survodutide's phase 3 escalation table and half-life have not been published in the sources read, and TRIUMPH-1 is known from Lilly's release rather than a peer-reviewed paper. Research-market vials sold under either name have no data of their own. The compounds are covered in Medibact's survodutide guide and retatrutide guide. Nothing on this page is an instruction; dose and product belong with a clinician.
Sources and dates
Opened 2026-10-04: PubMed abstracts 42253238 (le Roux et al., NEJM 2026), 38330987 (le Roux et al., Lancet Diabetes Endocrinol 2024), 37366315 (Jastreboff et al., NEJM 2023) and 39724554 (Tetelbaun et al., Cardiology in Review); ClinicalTrials.gov intervention search for survodutide AND retatrutide (zero records). The survodutide phase 2 escalation, the phase 3 design paper and the Klein review are as recorded on this site's survodutide page (2026-09-26); the TRIUMPH figures and Lilly's filing plan are as recorded on its retatrutide page from Lilly's releases of 2026-05-21 and 2026-07-23 (the release itself timed out when re-opened on 2026-10-04). Unit figures are arithmetic by this site. Corrections go to the contact page.