Update
GLP-1, GLP-2 and GLP-3 on a vendor listing are not what they sound like
Twenty of the vendors we read have stopped printing 'semaglutide' and 'tirzepatide' at all. The code they use instead is consistent across the market, and it is not pharmacology.
If you have shopped for these compounds recently you will have seen listings called GLP-1 S, GLP-2 TZ or GLP-3 RT, with no compound name anywhere on the page. Some vendors go further: AMP-1P, GLA-2 TRZ, OC-3RT, TIRZ-60. The pattern is now the majority of how these three compounds are sold.
The numbering is the market's invention, not a pharmacological classification, and that is the first thing worth being clear about. There is no such receptor as GLP-3. GLP-2 is a real hormone and it is not tirzepatide. What the numbers encode is simply an ordering: GLP-1 is semaglutide, GLP-2 is tirzepatide, GLP-3 is retatrutide, and the letters after them are the compound's initials.
We did not want to encode a guess, so we checked it three ways. Three vendors spell it out in the same listing — one sells a product titled 'GLP 2 TIRZEPATIDE'. One prints CAS numbers, and 910463-68-2, 2023788-19-2 and 2381089-83-2 are semaglutide, tirzepatide and retatrutide respectively. And the letter suffixes agree across every vendor using them: S, SG and SM for the first, T, TZ and TRZ for the second, R and RT for the third.
The reason for the code is not stated by anyone using it, and we are not going to speculate about intent. What we can say is what it costs a buyer. A listing with no compound name cannot be checked against a reference, cannot be searched for by name, and gives a reader nothing to compare against the trial literature for the drug they are actually buying. Whatever else it does, it puts distance between a product and the evidence about it.
Our price index now reads these codes, so a GLP-2 TZ listing is priced against tirzepatide and appears on the tirzepatide page alongside listings that name it. One deliberate exception: bare 'GLP-1' and bare 'GLP-2', with no letter after them, are left unresolved and go to a person to decide. GLP-1 is how every drug in the class is described, and GLP-2 could reasonably be teduglutide. Bare 'GLP-3' is resolved, because there is nothing else it could mean.
Compounds this concerns
This page is educational. It describes what published research reports, not what you should do. Peptides discussed here are largely not approved for human use, and nothing on Bioalmanac is medical advice.