Ozempic vs Retatrutide: What the Research Shows
Semaglutide — the molecule inside Ozempic and Wegovy — turned GLP-1 agonists into household names. Retatrutide is the compound researchers increasingly call the “next generation”: rather than acting on one receptor, it acts on three. This guide compares the two on mechanism and on the weight-change figures reported in their clinical trials.
Everything here is educational and refers to published research. Retatrutide is investigational and is supplied by PX1 Labs strictly for laboratory research use only.
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One receptor versus three
Semaglutide is a single agonist: it activates the GLP-1 receptor. Retatrutide is a triple agonist — it activates the GLP-1, GIP and glucagon receptors at once. That extra GIP and glucagon signalling is the structural reason researchers expect a larger metabolic effect: glucagon-receptor activity in particular is associated with increased energy expenditure, on top of the appetite and satiety effects shared across the GLP-1 class.
In short, where Ozempic pulls one metabolic lever, retatrutide pulls three.
Weight change in the trials
The headline numbers come from separate trials, so they are not a direct head-to-head — but the direction is consistent:
- Retatrutide ≈ 24.2% mean body-weight reduction at 48 weeks (12 mg) — phase-2 trial, New England Journal of Medicine, 2023.
- Tirzepatide ≈ 20.9% at 72 weeks (15 mg) — SURMOUNT-1, 2022 (a dual GIP/GLP-1 agonist).
- Semaglutide ≈ 14.9% at 68 weeks (2.4 mg) — STEP-1, 2021.
Where tirzepatide fits
Tirzepatide (the molecule in Mounjaro and Zepbound) is the bridge between the two: a dual GIP/GLP-1 agonist. Its trial weight change (≈21%) sits between semaglutide’s single-agonist result and retatrutide’s triple-agonist result — which is part of why the field reads the progression from one to two to three receptors as a clear line of advancement.
Approval status — and what “research use only” means
Semaglutide and tirzepatide are approved medicines. Retatrutide is still investigational — in late-stage clinical trials — and is not an approved drug. PX1 Labs supplies retatrutide as a research-grade compound for laboratory and in-vitro research use only; it is not for human or veterinary use. Ozempic, Wegovy, Mounjaro and Zepbound are registered trademarks of their respective owners (Novo Nordisk and Eli Lilly); PX1 Labs is independent and is not affiliated with or endorsed by either company.
Retatrutide at PX1 Labs
PX1 Labs supplies retatrutide as a 10 mg lyophilized vial verified at 99%+ identity purity by HPLC, with a lot-specific Certificate of Analysis in every order, at €89.95 and free EU shipping. Supplied for laboratory research use only. You can also see the side-by-side comparison on the product page.
Frequently asked questions
Is retatrutide better than Ozempic?
In their separate clinical trials, retatrutide produced a larger mean weight reduction (about 24% versus about 15% for semaglutide) and it acts on three receptors rather than one. However, these are different trials with different designs, and retatrutide is still investigational and not an approved medicine — so it is not a like-for-like or regulatory comparison.
What is the difference between Ozempic and retatrutide?
Ozempic contains semaglutide, a single GLP-1 receptor agonist. Retatrutide is a triple agonist acting on the GLP-1, GIP and glucagon receptors. That added GIP and glucagon activity is why researchers describe it as a next-generation compound.
Is retatrutide approved or available like Ozempic?
No. As of 2026 retatrutide is investigational and in late-stage clinical trials; it is not an approved drug or prescription medicine. PX1 Labs supplies it strictly for laboratory research use only.
Why does targeting three receptors matter?
GLP-1 drives appetite and satiety effects; GIP adds complementary metabolic signalling; glucagon-receptor activity is associated with increased energy expenditure. Combining all three is the rationale for the larger weight changes observed in retatrutide trials.