Semaglutide vs tirzepatide: single or dual incretin agonism?
Semaglutide is a GLP-1 receptor agonist and the most-studied compound in the incretin class. Tirzepatide adds GIP receptor activity. Choose semaglutide as the reference for any GLP-1 question; choose tirzepatide when the GIP pathway or the interaction between the two receptors is the question. Both are lot-tested and sold for laboratory research only.
| Semaglutide | Tirzepatide | |
|---|---|---|
| Receptors | GLP-1 | GIP, GLP-1 |
| Length | 31 amino acids | 39 amino acids |
| Backbone | Human GLP-1 analogue | GIP-derived |
| Half-life basis | C18 fatty diacid, about 7 days | C20 fatty diacid, about 5 days |
| Distinguishing property | Largest published dataset in the class | GIP receptor bias |
| Typical research use | GLP-1 reference compound; cardiovascular, renal, CNS models | Dual-incretin signalling; comparison against GLP-1-only |
| Key clinical context | STEP 1, NEJM 2021; SELECT, NEJM 2023 | SURMOUNT-1, NEJM 2022 |
| Current lot purity | 99.6% (SM-2608-B) | 99.2% (TZ-2608-C) |
| Vial | 5 mg, $95 | 10 mg, $120 |
Why start with semaglutide?
Because everything else in the class is measured against it. The GLP-1 receptor is expressed in pancreas, gut, brain, heart and kidney, and semaglutide's literature covers all of them, so a semaglutide arm gives a study a reference point that reviewers recognise.
What does GIP add, and is it agonism that matters?
GIP receptor activation potentiates insulin release and acts on adipose tissue and central appetite circuits. Whether tirzepatide's effect comes from GIP agonism, from its particular receptor bias, or from something else is an open research question, and it is the reason tirzepatide is worth studying rather than treating as a stronger semaglutide.
Which vial size?
Semaglutide is supplied at 5 mg and tirzepatide at 10 mg, reflecting the concentrations typical in their respective assays. The Metabolic trio bundle adds retatrutide for a three-arm design.
Common questions
What does adding GIP change?
Tirzepatide engages GIP alongside GLP-1, so any difference against semaglutide in the same model is attributable to GIP receptor activity. That is the comparison most study designs are built to make.
Do they reconstitute the same way?
Both are acylated and dissolve slowly. Swirl rather than shake and allow time; the reconstitution guide covers the volumes.
Where to go next
- Semaglutide research guide · Semaglutide product page
- Tirzepatide research guide · Tirzepatide product page
For laboratory research use only. Clinical trial results are cited as context and do not describe use of the material sold here.
