What is Retatrutide?
Retatrutide is a synthetic research peptide — a small chain of amino acids engineered in a laboratory — that activates three hormone receptors in the body simultaneously. It was developed by Eli Lilly (the pharmaceutical company behind Mounjaro and Zepbound) and is currently in Phase 3 clinical trials for obesity and metabolic disease.
In June 2023, a study published in the New England Journal of Medicine showed that people taking the highest dose of Retatrutide lost an average of 24.2% of their body weight in 48 weeks — the greatest weight loss ever measured from a drug in a clinical trial, without surgery.
To put 24.2% in perspective: if someone weighs 250 lbs, that's about 60 lbs lost in less than a year. Bariatric surgery typically produces 25–35% weight loss — Retatrutide is approaching surgical territory with a weekly injection.
The Names: Reta, LY3437943, Triple G, QSC RT10
You'll encounter Retatrutide under several names depending on where you find it:
- Retatrutide — the official international nonproprietary name (INN) assigned by the World Health Organization
- Reta — common shorthand used by researchers and the peptide community
- LY3437943 — Eli Lilly's internal development code, which you'll see in scientific papers
- Triple G — informal nickname referencing its three receptor targets (GIP + GLP-1 + Glucagon)
- QSC RT10 — QSC Peptides' product identifier, referring to the common 10mg research vial size
They all refer to the same molecule. When searching for Retatrutide research products, any of these terms — buy reta, QSC RT10, QSC reta, shop retatrutide — will lead to the same compound.
How Retatrutide Works — Plain English Version
Your body has hormones that control hunger, blood sugar, and how much energy you burn. Retatrutide mimics three of these hormones at the same time — GIP, GLP-1, and glucagon — by "fitting into" the receptors (docking stations) these hormones normally use.
Think of it like having three separate weight-loss mechanisms firing at once:
- You eat less — because GLP-1 activation tells your brain you're full and makes food move through your stomach more slowly
- Your body handles glucose better — because GIP + GLP-1 activation improves how your pancreas releases insulin
- You burn more energy at rest — because glucagon activation increases your resting metabolic rate and directly stimulates fat breakdown (lipolysis)
No other approved drug or research peptide activates all three of these pathways simultaneously. This is why Retatrutide's results exceed everything that came before it.
The Three Receptors — A Closer Look
Glucose-Dependent Insulinotropic Polypeptide
GIP is an incretin hormone produced in your small intestine after eating. GIP receptor activation boosts insulin secretion, improves fat cell sensitivity, and reduces inflammation in adipose tissue. It's the same receptor tirzepatide (Mounjaro) targets alongside GLP-1.
Glucagon-Like Peptide-1
GLP-1 is the hormone mimicked by Ozempic and Wegovy (semaglutide). It's the most powerful appetite suppressant of the three — reducing hunger signals in the brain, slowing gastric emptying, and improving post-meal blood sugar. It's the foundation of all modern weight-loss peptides.
Glucagon — The Secret Weapon
Glucagon is the hormone that raises blood sugar and mobilizes stored energy. Activating glucagon receptors increases how many calories your body burns at rest, accelerates fat breakdown (lipolysis), and drives liver fat reduction. This is the receptor Ozempic and Mounjaro don't target — and the reason Retatrutide outperforms both.
What the Clinical Trials Actually Showed
The landmark Phase 2 trial enrolled 338 adults with BMI ≥27 and tested six active doses of Retatrutide over 48 weeks. The results:
Beyond weight loss, participants showed significant improvements in blood pressure, triglycerides, cholesterol, and fasting glucose — a broad metabolic benefit profile that positions Retatrutide as relevant to cardiovascular, diabetes, and liver disease research as well as obesity.
Retatrutide vs Ozempic, Wegovy, Mounjaro, Zepbound
The most common question: how does Retatrutide compare to the drugs people have already heard of?
| Drug | Type | Receptors | Avg Weight Loss | Status |
|---|---|---|---|---|
| Ozempic / Wegovy (semaglutide) |
Single agonist | GLP-1 only | ~14.9% (68 wks) | ✓ FDA Approved |
| Mounjaro / Zepbound (tirzepatide) |
Dual agonist | GIP + GLP-1 | ~20.9% (72 wks) | ✓ FDA Approved |
| Retatrutide (Reta) (LY3437943) |
Triple agonist | GIP + GLP-1 + Glucagon | 24.2% (48 wks) ↑ | ⏳ Phase 3 Trials |
Weight loss percentages from respective Phase 2/3 trials. Retatrutide results extrapolated from NEJM June 2023 Phase 2 trial. Not a direct head-to-head comparison.
Research Protocol Basics
For researchers studying Retatrutide, the Phase 2 trial protocol provides the reference framework that most research designs reference:
- Administration: Subcutaneous (under the skin) injection, once weekly
- Dose escalation: The trial used a step-up protocol, starting at lower doses (1–2 mg/week) and escalating over 24 weeks to the target maintenance dose
- Dose range studied: 1 mg, 2 mg, 4 mg, 8 mg, and 12 mg/week
- Duration: 24-week escalation phase + 24-week maintenance phase = 48 weeks total
- Reconstitution: Lyophilized Retatrutide powder is reconstituted with bacteriostatic water before use
- Storage: Lyophilized (dry) powder: refrigerate (2–8°C) or freeze (−20°C). After reconstitution: refrigerate and use within 28–30 days
Research Use Only: This protocol information is provided for scientific reference from published clinical trial data. Retatrutide is not approved for human therapeutic use. All research must comply with applicable institutional and regulatory requirements.
Storage & Handling
Retatrutide arrives as a lyophilized (freeze-dried) white powder in sealed vials. Proper storage is essential for maintaining peptide integrity:
- Before reconstitution (dry powder): Store at 2–8°C (refrigerator) for up to 3–4 months. For longer storage (months to years), freeze at −20°C. Keep away from light and moisture. Do not allow repeated temperature cycling.
- After reconstitution (in solution): Refrigerate at 2–8°C. Use within 28–30 days. Never refreeze reconstituted peptide. Gently swirl to mix — do not shake vigorously.
- Reconstitution: Use bacteriostatic water (0.9% benzyl alcohol in sterile water). Add slowly down the side of the vial, allow to dissolve without agitation.
- Shipping: QSC ships all Retatrutide in lyophilized form, which is stable at room temperature for several weeks during transit — no cold packs required for shipment.
Where to Buy Retatrutide for Research
Research-grade Retatrutide is available from QSC Peptides at qscpeptide.com, accessible via ShopReta.com. QSC offers:
- ≥99% HPLC-verified purity with COA on every order
- 9 vial concentrations from 5mg to 100mg
- 10-vial and 20-vial kit options
- Domestic warehouses in USA, EU, UK, Australia, and Canada
- Free shipping on all orders
- Prices from $0.76/mg (bulk) to $3.80/mg (starter kits)
For a full pricing breakdown and comparison to other suppliers, see the Retatrutide Price Comparison page. For specific purchase guidance, see the Buyer's Guide.