Retatrutide
Triple agonist in phase 3 — GIP, GLP-1 and glucagon
Experimental material. Read before using anything from here.
Nothing on this page is a medical recommendation, prescription or treatment plan. It is an organized translation of protocols circulating in research communities and, where it exists, of what published trials tested. The two are marked differently — and they are not equivalent.
Most of the compounds here have no FDA approval for human use. Several are sold labeled "research use only", which means they have not gone through purity, sterility or dosage controls for human consumption. A community-reported dose is not a validated dose: it is what someone reported having done.
Talk to a licensed health professional before considering any of these compounds. If you already use one and feel anything unexpected, seek care — do not wait for the next routine test.
No package insert, no approved dose
This compound has no FDA registration — checked in the label database on September 4, 2026. That does not make it safer than semaglutide or tirzepatide, which carry a black box warning: it makes it less known. There is no approved titration ladder, no defined maximum dose and no official contraindication list to compare with the tables on this page.
The related analogs that already have a package insert carry a thyroid C-cell tumor warning — and tirzepatide is contraindicated in medullary thyroid carcinoma and MEN 2 in the package inserts of both countries, while semaglutide is only in the United States. The full audit is in The GLP-1s against the package insert.
Summary
Weekly triple receptor agonist, under investigation and in phase 3 trials. It activates GIP, GLP-1 and glucagon receptors at the same time. It is important to separate the escalation design of the TRIUMPH program, which is public, from the schedules that circulate in the community — they are not the same thing.
Quick reference
- Route
- Subcutaneous injection in clinical trials.
- Frequency
- 1×/week in the published phase 2 and 3 studies.
- Starting dose (phase 3)
- 2 mg 1×/week, with an increase every 4 weeks.
- Phase 3 targets
- 4 mg, 9 mg or 12 mg, depending on the TRIUMPH trial arm.
Phase 3 TRIUMPH Retatrutide Titration Schedule
| Weeks | Weekly dose | Trial-design note |
|---|---|---|
| 1-4 | 2 mg | Starting dose used across the initial TRIUMPH Phase 3 program. |
| 5-8 | 4 mg | First escalation step. Also a target dose in TRIUMPH-1 and TRIUMPH-2. |
| 9-12 | 6 mg | Intermediate escalation step before the 9 mg or 12 mg target. |
| 13-16 | 9 mg | Target dose in the initial TRIUMPH program; also a step toward 12 mg. |
| 17+ | 12 mg | Highest target dose in the initial TRIUMPH program. |
Phase 2 Retatrutide Dose Arms
| Target dose | Initial dose | Study context |
|---|---|---|
| 1 mg | 1 mg | Fixed 1 mg arm |
| 4 mg | 2 mg | 4 mg target with lower starting dose |
| 4 mg | 4 mg | 4 mg target without the lower start |
| 8 mg | 2 mg | 8 mg target with lower starting dose |
| 8 mg | 4 mg | 8 mg target with higher starting dose |
| 12 mg | 2 mg | Highest Phase 2 target with a 2 mg starting dose |
Retatrutide Reconstitution Guide
| Vial size | BAC water added | Concentration | 1 mg | 2 mg | 4 mg | 6 mg | 9 mg | 12 mg |
|---|---|---|---|---|---|---|---|---|
| 5 mg | 1.0 mL | 5 mg/mL (5,000 mcg/mL) | 0.20 mL (20 units) | 0.40 mL (40 units) | 0.80 mL (80 units) | Exceeds vial | Exceeds vial | Exceeds vial |
| 10 mg | 2.0 mL | 5 mg/mL (5,000 mcg/mL) | 0.20 mL (20 units) | 0.40 mL (40 units) | 0.80 mL (80 units) | 1.20 mL - split draw or 2 vials | Requires 2 vials | Requires 2-3 vials |
| 12 mg | 1.2 mL | 10 mg/mL (10,000 mcg/mL) | 0.10 mL (10 units) | 0.20 mL (20 units) | 0.40 mL (40 units) | 0.60 mL (60 units) | 0.90 mL (90 units) | 1.20 mL - split draw |
| 20 mg | 2.0 mL | 10 mg/mL (10,000 mcg/mL) | 0.10 mL (10 units) | 0.20 mL (20 units) | 0.40 mL (40 units) | 0.60 mL (60 units) | 0.90 mL (90 units) | 1.20 mL - split draw |
| 30 mg | 3.0 mL | 10 mg/mL (10,000 mcg/mL) | 0.10 mL (10 units) | 0.20 mL (20 units) | 0.40 mL (40 units) | 0.60 mL (60 units) | 0.90 mL (90 units) | 1.20 mL - split draw |
Retatrutide 12 mg Dosage and Concentration Chart
| Reference amount | Volume at 10 mg/mL | U-100 units |
|---|---|---|
| 2 mg | 0.20 mL | 20 units |
| 4 mg | 0.40 mL | 40 units |
| 6 mg | 0.60 mL | 60 units |
| 9 mg | 0.90 mL | 90 units |
| 12 mg | 1.20 mL | 120 units |
Dose-by-dose weight loss in Phase 2 (NEJM)
| Dose | 24 weeks | 48 weeks |
|---|---|---|
| 1 mg | -7,2% | -8,7% |
| 4 mg | -12,9% | -17,5% |
| 8 mg | -15,7% | -22,8% |
| 12 mg | -17,5% | -24,2% |
| Placebo | -1,6% | -2,1% |
Retatrutide vs Tirzepatide vs Semaglutide
| Category | Retatrutide | Tirzepatide | Semaglutide |
|---|---|---|---|
| Receptor targets | GLP-1 + GIP + Glucagon (triple) | GLP-1 + GIP (dual) | GLP-1 only (single) |
| Half-life | ~6 days | ~5 days | ~7 days |
| Dose frequency | 1×/week | 1×/week | 1×/week |
| Max studied dose | 12 mg/week | 15 mg/week | 2.4 mg/week |
| Peak weight loss in trials | -28.7% at 68 weeks (Phase 3 TRIUMPH-4) | -22.5% at 72 weeks (SURMOUNT-1) | -15.8% at 68 weeks (STEP-1) |
| FDA status (August 2026) | Investigational, Phase 3 | Approved (obesity + T2D) | Approved (obesity + T2D) |
| Liver fat | Up to 82% reduction (Phase 2 substudy) | Significant reduction | Moderate reduction |
| Unique angle | Triple agonism may raise energy expenditure via glucagon pathway | Dual agonism balances effect and tolerability | Longest clinical track record; CV outcomes data (SELECT) |
KPV Cycle Length Chart
| Duration | Study | What the duration means |
|---|---|---|
| 12 weeks | Phase 1b in adults with type 2 diabetes | Early proof-of-concept study focused on safety, tolerability, pharmacokinetics, and pharmacodynamics. It did not establish a 12-week cycle standard. |
| 36 weeks | Phase 2 type 2 diabetes trial | Later Phase 2 efficacy and safety outcomes were assessed through week 36. |
| 40 weeks | TRANSCEND-T2D-1 Phase 3 | Phase 3 treatment period in adults with type 2 diabetes inadequately controlled with diet and exercise. |
| 48 weeks | Phase 2 obesity trial | Treatment continued for 48 weeks, even though the primary weight endpoint was measured earlier at week 24. |
| 68 weeks | TRIUMPH-4 Phase 3 | Primary Phase 3 evaluation period in adults with obesity or overweight and knee osteoarthritis without diabetes. |
| 80 weeks | TRIUMPH-1, TRIUMPH-2, and TRIUMPH-3 | Primary Phase 3 outcome period used across several large obesity studies with different participant groups. |
| 104 weeks | TRIUMPH-1 extension | A pre-specified blinded extension followed a subgroup with baseline BMI of at least 35 through two years of treatment. |
| 80 + 36 weeks | TRIUMPH-6 maintenance study | Ongoing study with an 80-week retatrutide lead-in followed by 36 weeks of continued retatrutide, a different retatrutide dose, or placebo. Results are not yet available. |
Retatrutide Cycle Length vs Titration
| Question | Best page | What belongs there |
|---|---|---|
| How long was retatrutide studied? | This cycle guide | 12-, 36-, 40-, 48-, 68-, 80-, and 104-week research timelines |
| Is a 12-week cycle supported? | This cycle guide | What the 12-week Phase 1b study can and cannot establish |
| How much time off is supported? | This cycle guide | Maintenance, withdrawal, and the lack of a validated off-cycle period |
| What was the Phase 3 starting dose? | Retatrutide Protocol Guide | Starting dose and trial-specific dose design |
| What is the titration schedule? | Retatrutide Protocol Guide | Dose escalation and target-dose arms |
| How do vial and syringe calculations work? | Retatrutide Protocol Guide | Reconstitution, concentration, and U-100 calculation examples |
Storage and handling
The rules below apply to practically every lyophilized peptide in this reference. Where a compound has its own requirement, it appears in the table in the previous section.
- Lyophilized powder, sealed: refrigerator, between 2 and 8 °C, protected from light. Many tolerate room temperature for short transport periods, but that is tolerance, not a recommendation.
- After reconstitution: always refrigerated, between 2 and 8 °C. The stability window drops to days or a few weeks, depending on the compound.
- Never freeze after reconstituting. The freeze–thaw cycle degrades the peptide.
- Do not shake. Swirl the vial slowly. Shaking breaks the peptide chain.
- Bacteriostatic water down the wall of the vial, in a slow stream, not squirted directly onto the powder.
- Cloudy solution, with particles or a color change: discard. There is no recovery.
Lab tests and monitoring
This list is the one that appears recurrently in the source, with small variations by compound. It serves as a starting point for a conversation with a professional — not as a substitute for that conversation.
- Before starting: complete blood count, comprehensive metabolic panel, lipid panel, fasting glucose and HbA1c, TSH and free T4, blood pressure and resting heart rate.
- Depending on the compound: IGF-1 (GH axis), lipase and amylase (VIP and the incretin agonists), serum copper and ceruloplasmin (GHK-Cu and blends containing it), CRP.
- Reassessment: most protocols review between week 4 and week 8, and then every 8–12 weeks.
- Do not wait for the routine lab test in the face of abdominal pain, visual changes, a change in a mole, shortness of breath, asymmetric swelling or any new and persistent symptom. That is a reason to seek care, not a spreadsheet item.
Evidence limits
Data source: peptidedosingprotocols.com, accessed on September 3, 2026. Translation and organization in Portuguese are original work. No primary source (PubMed, trial registry, package insert) was checked in building this page — the check was against the secondary source, and that alone.