Retatrutide vs. Tirzepatide vs. Semaglutide: GLP Receptor Research Peptides Compared (2026)

Summary: Semaglutide, tirzepatide, and retatrutide are three peptides widely studied in metabolic research. Their main difference is how many incretin receptors they target: semaglutide acts on one (GLP-1), tirzepatide on two (GLP-1 and GIP), and retatrutide on three (GLP-1, GIP, and glucagon). This overview compares them as research compounds.

Semaglutide — single GLP-1 receptor agonist

Semaglutide is a GLP-1 receptor agonist and the most-studied single-incretin peptide in this class. In research it often serves as the reference point that dual- and triple-agonists are compared against.

Tirzepatide (TRZ) — dual GLP-1 / GIP agonist

Tirzepatide activates two incretin receptors, GLP-1 and GIP, and is often described as a “twincretin.” It is studied for the combined effect of engaging both pathways at once. Next Gen Peptides lists it under the research shorthand TRZ.

Retatrutide (GLP-3) — triple GLP-1 / GIP / glucagon agonist

Retatrutide adds glucagon-receptor activity to the GLP-1 and GIP targets, making it the most complex of the three in receptor pharmacology — which is why the research community sometimes calls it “GLP-3.” NGP lists it as GLP-3.

Where cagrilintide fits

Cagrilintide is an amylin-receptor analog rather than an incretin agonist, and is frequently studied alongside these peptides in combination research. NGP carries it as Cagri.

Choosing one for research

The right compound depends entirely on the receptor pathway a study is designed around — single (GLP-1), dual (GLP-1/GIP), or triple (adding glucagon). Whichever you evaluate, sourcing quality matters: every batch NGP supplies is identity- and purity-tested by ILS Labs (ISO/IEC 17025), with batch COAs in the COA Library.

All products are supplied strictly for laboratory and in-vitro research use only (RUO). They are not intended for human or veterinary use, and no dosing or administration guidance is provided.