Semaglutide vs. Tirzepatide vs. Retatrutide: GLP-1 Research Peptides Compared

By the Proper Peptides team · October 21, 2026 · 7 min read

Mono, dual and triple agonists

Semaglutide — GLP-1 receptor agonist
Tirzepatide — dual GIP/GLP-1 receptor agonist
Retatrutide — triple GIP/GLP-1/glucagon receptor agonist (investigational)

Research vs. prescription products

Semaglutide and tirzepatide are active ingredients in FDA-approved prescription medicines. Research-grade vials sold by Proper Peptides are not those medicines, are not for human use, and are supplied strictly for laboratory study.

Related metabolic compounds

Labs exploring amylin signaling also study cagrilintide, and some compare these with AOD-9604 or 5-Amino-1MQ in metabolic models.

Frequently asked questions

What's the difference between semaglutide and tirzepatide?: Semaglutide activates the GLP-1 receptor; tirzepatide activates both GLP-1 and GIP receptors.
Is retatrutide approved?: As of this writing retatrutide is investigational and not FDA-approved.

References & regulatory context

These sources provide context, not testing or certification of Proper Peptides products. Findings about other materials do not establish the identity, purity or suitability of your batch.

FDA concerns about unapproved GLP-1 products

Peptides in this article

Semaglutide →Tirzepatide →Retatrutide →Cagrilintide →

Everything Proper Peptides sells is for laboratory research use only. Nothing here is medical advice, a treatment claim or a dosing recommendation for humans or animals.