GLP-1 Analog Nomenclature: Research-Use Naming for Retatrutide, Tirzepatide & Related Peptides

Investigational incretin mimetics move through two parallel naming systems, and researchers ordering reference material for in-vitro work routinely need to translate between them. The name a molecule carries in a clinical trial registration or a peer-reviewed pharmacology paper is often not the identifier that appears on a research-use-only (RUO) supplier catalog, spec sheet, or certificate of analysis. This gap is a common source of ordering errors, mismatched literature searches, and misinterpreted assay results, especially for newer dual and triple agonists in the GLP-1 class.

Pharmaceutical developers assign internal codes early in a program (typically a company prefix plus a numeric identifier), then a nonproprietary International Nonproprietary Name (INN) once the molecule reaches later-stage development, and finally a brand name at commercialization. Research suppliers, by contrast, sell reference-grade material under the chemical or investigational identifier rather than the branded or INN name, because the product is not intended for therapeutic use and the branded name carries regulatory and trademark implications. Understanding which identifier lives in which context prevents ordering the wrong compound or citing an unrelated sequence in a methods section.

This guide maps the working nomenclature for the most-searched GLP-1, GIP, and glucagon-receptor peptides so laboratory personnel can locate reference material accurately and match batch documentation to the identifier used in the primary literature.

Retatrutide is the INN for the investigational triple agonist developed by Eli Lilly and originally designated LY3437943 in preclinical and early clinical literature. It acts at the glucagon-like peptide-1 receptor (GLP-1R), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon receptor (GCGR), placing it in a distinct pharmacological class from single- or dual-receptor agonists. Reference-grade material sold for in-vitro study will almost always be listed as retatrutide or LY3437943 on an RUO supplier site; the two names refer to the same 39-residue lipidated peptide.

When searching primary literature, researchers should query both identifiers. Early pharmacology and toxicology papers (2020–2022) predominantly used the LY3437943 code, while later clinical publications shifted to the INN. Certificates of analysis from research suppliers typically report the identifier under the label "chemical name" or "compound identifier"; the branded or trade name should not appear on RUO documentation because there is no approved commercial product bearing a trade name for retatrutide as of the current literature cutoff.

Sequence, molecular weight, and modification pattern (fatty-acid conjugation for albumin binding) are the identity attributes to verify against published characterization data before use in an assay. A COA that reports mass by LC-MS and purity by RP-HPLC against the retatrutide reference sequence is the standard identity check.

Tirzepatide is the INN for the dual GLP-1/GIP receptor agonist originally designated LY3298176. The commercial brand names (Mounjaro for type 2 diabetes and Zepbound for weight management) apply only to the finished pharmaceutical product and should not be used to identify research-grade reference material. RUO suppliers list this molecule as tirzepatide or LY3298176.

Tirzepatide is a 39-residue peptide with a C20 fatty-diacid moiety conjugated via a linker to the lysine at position 20. This modification extends its half-life through albumin binding and is a critical identity attribute for characterization. Confirming both the peptide backbone sequence and the presence of the lipid modification is standard when qualifying a reference lot; a purity result without a mass-spec confirmation of the conjugated modification is incomplete.

In older preclinical literature the compound also appears as LY3298176 or as "tirzepatide (LY3298176)" in mixed nomenclature. Search both to retrieve the full historical pharmacology record.

Semaglutide (NN9535 during Novo Nordisk development) and liraglutide (NN2211) are the two most-characterized long-acting GLP-1 receptor agonists. Both are sold as pharmaceuticals under multiple brand names (Ozempic, Wegovy, Rybelsus for semaglutide; Victoza, Saxenda for liraglutide), none of which apply to research-use material. RUO reference material is listed under the INN or the historical NN code.

Both molecules are lipidated GLP-1(7-37) analogs with substitutions that resist DPP-4 cleavage. Semaglutide carries an Aib substitution at position 8 and a C18 fatty-diacid modification via a spacer at Lys26; liraglutide carries a C16 fatty acid via a glutamic-acid spacer at Lys26 with no Aib substitution. These structural differences drive the substantial half-life gap between the two compounds and are the correct identity attributes to verify on any reference lot.

Older peptide catalogs sometimes list liraglutide under NN2211; more recent catalogs use only the INN. Sequence and modification pattern remain the definitive identity check in either case.

The following mapping covers the incretin-class peptides most frequently requested for in-vitro study. Each row lists the INN, the original investigational or company code, and the receptor pharmacology. Use the INN or the investigational code when ordering; do not use trade names on purchase orders or in methods sections for research-grade material.

Retatrutide — LY3437943 — GLP-1R / GIPR / GCGR triple agonist. Tirzepatide — LY3298176 — GLP-1R / GIPR dual agonist. Semaglutide — NN9535 — GLP-1R agonist. Liraglutide — NN2211 — GLP-1R agonist. Dulaglutide — LY2189265 — GLP-1R agonist (Fc-fusion, not a linear peptide). Exenatide — AC2993 — GLP-1R agonist (synthetic exendin-4 analog). Cagrilintide — NNC0174-0833 — amylin receptor agonist (frequently co-formulated with semaglutide in research studies).

When a compound has been through multiple developers or licensing changes, more than one investigational code may appear in the literature; the INN is the most stable identifier across sources and is the recommended primary reference when writing methods.

When ordering reference material for in-vitro work, match the identifier on the supplier product page to the identifier used in the source literature for your assay. If the paper cites LY3437943 and the supplier lists retatrutide, those are the same molecule; a mismatch in sequence, mass, or modification pattern on the certificate of analysis is the signal that something is wrong, not a mismatch in name.

Certificates of analysis for research-grade GLP-1 class peptides should report: sequence confirmation (typically by MS/MS or Edman where feasible), monoisotopic and average mass by LC-MS, purity by RP-HPLC (industry norm is ≥95% for research use, ≥98% for reference standards), and where relevant, endotoxin level for cell-culture applications. The identifier printed on the COA should match the identifier on the vial label and the shipping documentation.

For methods sections, cite the compound by its INN with the investigational code in parentheses at first mention (for example, "retatrutide (LY3437943)"). This convention makes the compound unambiguously locatable in both current and historical databases and matches the citation practice of most peer-reviewed pharmacology journals.

These peptides are supplied strictly for in-vitro laboratory research. They are not for human or veterinary use, and no information in this guide constitutes clinical, dosing, or therapeutic advice.