Three names dominate metabolic peptide research: semaglutide, tirzepatide and retatrutide. The simplest way to tell them apart is to count the receptors each one targets: one, two or three.
Last updated 27 October 2026 · Written by the SHLabz research team
At a Glance
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Receptors | GLP-1 | GLP-1 + GIP | GLP-1 + GIP + glucagon |
| Class | Mono-agonist | Dual agonist | Triple agonist |
| Development status | Approved medicine | Approved medicine | Investigational |
| SHLabz | Not stocked | Not stocked | SH-R vial and pen |
The Receptors
GLP-1 (glucagon-like peptide-1) receptors influence insulin secretion, gastric emptying and appetite signalling. GIP (glucose-dependent insulinotropic polypeptide) receptors are a second incretin pathway. Glucagon receptors act on the liver and energy expenditure. Each extra receptor adds another lever, and another variable, in research models.
Semaglutide
Semaglutide is a long-acting GLP-1 receptor agonist. It is an approved prescription medicine in many countries, which is why SHLabz does not stock it: approved medicines belong in the regulated pharmacy channel.
Tirzepatide
Tirzepatide added GIP-receptor agonism to GLP-1, creating the first widely studied dual agonist. It is also an approved medicine.
Retatrutide
Retatrutide adds glucagon-receptor agonism to the GIP and GLP-1 pair. It remains investigational, which is why it is the subject of so much laboratory interest. SHLabz supplies it as the SH-R vial and pen for research use. See our retatrutide guide and SH-R pen vs vial.
Related Research Peptides
Cagrilintide, an amylin analogue, targets a different satiety pathway and is often discussed alongside incretin agonists. See our cagrilintide guide.
The Short Version
Semaglutide hits GLP-1; tirzepatide hits GLP-1 and GIP; retatrutide hits GLP-1, GIP and glucagon. The first two are approved medicines; retatrutide is investigational and is the one SHLabz supplies for research.
Frequently Asked Questions
What is a triple agonist? A compound acting on three receptors; for retatrutide, GLP-1, GIP and glucagon.
Does SHLabz sell semaglutide or tirzepatide? No.
What is SH-R? SHLabz’s retatrutide research product.
Is retatrutide approved? Not as of our knowledge; it is investigational.
References
These references describe published research. They do not establish safety or efficacy in humans.
Regulation in this area moves quickly. Check current rules with the relevant authority before ordering.
This article is provided for general research and educational purposes only. All SHLabz products are sold strictly for laboratory research use and are not intended for human or veterinary consumption, diagnosis, treatment, or prevention of any disease. Nothing in this article constitutes medical advice. Always consult a qualified professional and comply with applicable local regulations regarding the handling and use of research compounds.
