Liraglutide, semaglutide, tirzepatide and retatrutide compared

Evidence summary: These molecules differ in receptor pharmacology and evidence maturity. Liraglutide and semaglutide are GLP-1 receptor agonists; tirzepatide targets GIP and GLP-1 receptors; retatrutide targets GIP, GLP-1 and glucagon receptors. Trial outcomes cannot be ranked reliably across different populations and protocols without a direct head-to-head study.

Key findings

  • Approved branded medicines and Research Use Only materials are not interchangeable products.
  • SURPASS-2 directly compared tirzepatide with 1 mg semaglutide in type 2 diabetes.
  • Retatrutide evidence cited here is Phase 2; no direct retatrutide-versus-tirzepatide trial was identified.

Receptor targets and evidence stage

Liraglutide and semaglutide activate GLP-1 receptors. Tirzepatide is a dual GIP/GLP-1 receptor agonist, while retatrutide is designed as a GIP/GLP-1/glucagon receptor agonist.

Adding a receptor target does not automatically prove a superior outcome. Relative activity, exposure, trial population, comparator and endpoint all matter.

Semaglutide evidence

In STEP 1, 1,961 adults with overweight or obesity without diabetes were randomized to 2.4 mg semaglutide or placebo alongside lifestyle intervention. Mean body-weight change at 68 weeks was -14.9% versus -2.4%.

That result belongs to the studied prescription formulation, dose, population and monitoring—not to an uncharacterized RUO vial.

Tirzepatide evidence

SURPASS-2 randomized 1,879 participants with type 2 diabetes to tirzepatide or 1 mg semaglutide. Tirzepatide doses were noninferior and superior for the primary glycated-hemoglobin endpoint and produced greater weight reductions.

This is a direct comparison, but it does not compare tirzepatide with semaglutide's obesity-treatment dose or establish equivalence between branded medicines and research material.

Retatrutide evidence and comparison limits

A Phase 2 trial in 338 adults reported dose-dependent weight change up to -24.2% at 48 weeks for the 12 mg group versus -2.1% with placebo. Gastrointestinal adverse events were common and heart-rate increases were observed.

No published head-to-head randomized trial against tirzepatide or semaglutide was identified. Cross-trial percentages should not be presented as a ranking because populations, protocols and durations differ.

Regulatory and product distinction

Prescription liraglutide, semaglutide and tirzepatide products have approvals for defined indications and formulations. Retatrutide remains investigational as of this review.

PeptidesDirect catalog materials are sold strictly for laboratory research. Listing the same active molecule name does not make an RUO material an approved medicine, and this page provides no dosing or treatment guidance.

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Frequently asked questions

Which compounds have direct head-to-head evidence?

SURPASS-2 directly compared tirzepatide with 1 mg semaglutide in adults with type 2 diabetes.

Was retatrutide directly compared with tirzepatide?

No published direct randomized comparison was identified.

Are catalog materials equivalent to approved medicines?

No. Approved products have defined formulations, manufacturing controls, indications and regulatory review; RUO materials are not for human use.

Primary references

  1. Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2021. PubMed 33567185
  2. Frías JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021. PubMed 34170647
  3. Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med. 2023. PubMed 37366315

Related research materials

Research Use Only. Not for human or veterinary use. This page is not dosing or medical guidance.