Semaglutide, tirzepatide and retatrutide
What separates them is how many receptors they act on. Everything else follows from that.
The short version: semaglutide acts at one receptor, tirzepatide at two, retatrutide at three. That is the difference. Which one belongs in a protocol depends on which receptors that protocol is about.
| Compound | Receptor targets | Class |
|---|---|---|
| Semaglutide | GLP-1 | Single receptor analogue |
| Tirzepatide | GIP, GLP-1 | Dual agonist |
| Retatrutide | GIP, GLP-1, glucagon | Triple agonist |
What is the difference between semaglutide, tirzepatide and retatrutide?
They differ in how many receptors they act on. Semaglutide is a GLP-1 receptor analogue, acting at one. Tirzepatide is a dual agonist, acting at GIP and GLP-1. Retatrutide adds a third, glucagon, which is why it is described as a triple or GGG agonist. Each is a larger molecule than the last in terms of receptor coverage, not necessarily in size.
Is retatrutide the same as Ozempic?
No. Ozempic is a brand name for semaglutide, a single-receptor GLP-1 analogue approved as a therapeutic product. Retatrutide is a separate compound acting at three receptors, and it is not an approved therapeutic product in Canada or elsewhere. The material supplied here is research grade in either case and is not the branded pharmaceutical.
Which one is used most in research?
Semaglutide has the longest published record, simply because it has existed the longest and is the most widely studied of the three. Tirzepatide follows. Retatrutide is the newest and the literature on it is correspondingly thinner, which is worth knowing if you are choosing a reference compound where prior data matters.
Which should I choose?
That depends entirely on the receptor or receptors your protocol is investigating, and it is a question for whoever designed the protocol. This page describes what the compounds are; it does not recommend one over another, and no comparison of effects in people is offered here, because none of these are supplied for consumption.
Are they interchangeable?
No. Different receptor coverage means different experimental meaning, and their molecular weights differ, so a concentration calculated for one is not valid for another. Reconstitute and calculate per compound, per lot.
What this page does not tell you
It does not compare effects, outcomes or amounts. These are supplied for in vitro laboratory research, none of them are authorised by Health Canada, none are for human or animal consumption, and a comparison of what they do in people would be a clinical claim about unapproved material. If that is what you were looking for, this is the wrong supplier and the wrong page, and we would rather say so than write it.