Retatrutide
also known as LY3437943
Investigational triple-receptor agonist of GLP-1, GIP, and glucagon receptors developed by Eli Lilly, with Phase 3 trials ongoing as of 2026. The Phase 2 trial (Jastreboff et al., NEJM 2023) demonstrated 24.2% body-weight reduction at 12 mg over 48 weeks. [jastreboff-2023-reta]
- Class
- GLP-1 / GIP / Glucagon Triple Agonist
- Evidence level
- Phase 2 clinical
- Regulatory status
- Not FDA-approved (US) — research use only
At a glance
SQ · Abdomen · Once weekly
Primary target — GLP-1R + GIPR + Glucagon receptor (triple agonism) [jastreboff-2023-reta].
Pathway — Triple-receptor activation → ↑insulin (GLP-1+GIP), ↓gastric emptying, ↑lipid handling, ↑energy expenditure (glucagon component).
Downstream effect — Maximal weight loss across class. Glucagon component drives lipolysis and energy expenditure beyond GLP-1+GIP alone.
Origin — Synthetic peptide engineered for balanced affinity at three incretin / glucagon receptors.
| Parameter | Value |
|---|---|
| Standard dose | 12 mg / week (max efficacy)Phase 2 trial dose. Phase 3 dosing TBD. |
| Frequency | Once weekly |
| Titration schedule | 2 mg → 4 mg → 8 mg → 12 mg over 16 weeks |
| Evidence basis | Phase 2 trial; Phase 3 ongoing |
| Duration | Indefinite for chronic indication (presumed) |
| Reconstitution | Investigational; not commercially available |
| Timing | Any time of day |
| Half-life | ~6 days (estimated from class) |
Reconstitution
A pure mass-to-volume utility. Enter what you have in the vial; the atlas computes the volume per dose. No prescription information.
Lab verification
Third-party lab reports tied to batch codes, re-verifiable at the issuing lab. A fact and where to re-check it — never a verdict.
- — MTC personal or family history (presumed class effect)
- — Pregnancy / breastfeeding
- — Severe gastroparesis
- — History of pancreatitis
- — Severe cardiovascular disease (HR signal)
- 01Reconstitution
Investigational peptide. Research vials reconstituted with bacteriostatic water per label.
- 02Injection site
SQ — abdomen, thigh, or upper arm. Rotate weekly.
- 03Timing
Once weekly, same day.
- 04Storage
Refrigerate 2–8 °C. Light-protected.
- 05Needle
27–31G, 4–8 mm insulin syringe.
Frequently asked
How does Retatrutide work?
Retatrutide acts on GLP-1R + GIPR + Glucagon receptor (triple agonism). [jastreboff-2023-reta]
Is Retatrutide FDA-approved?
Retatrutide is not FDA-approved in the United States and is handled as a research compound (research use only). Regulatory status may differ in other jurisdictions.
Sources
of 41 rendered claims carry a resolvable citation.
- [jastreboff-2023-reta]Jastreboff 2023 — Triple-Hormone-Receptor Agonist Retatrutide for Obesity
N Engl J Med, 2023
Phase 2 retatrutide trial. -24.2% body weight at 12 mg over 48 weeks.