Peptide naming: INNs, development codes and trade names
Five naming layers for one molecule, how to move between them with a CAS number, where naming causes real problems, and how to write it in a methods section.
One peptide can carry five names: a development code, an international nonproprietary name, one or more brand names, a research-market nickname and a supplier's catalogue name. Confusion between them is a reliable source of mis-ordering and of misread literature. This note explains the naming systems, how to move between them, and how Alphex names things. All Alphex products are for laboratory and in-vitro research only.
The naming layers
- Development code. Assigned by the originating organisation: LY3437943, NNC 26-0161, PL 14736. Usually a company prefix and a serial number. These appear in early publications and patents and are often the most searchable identifier for preclinical work.
- International nonproprietary name (INN). Assigned by the World Health Organization for substances entering development: retatrutide, ipamorelin, semaglutide. INNs use stems that signal class: the "-tide" ending marks a peptide; "-glutide" indicates a glucagon-family analogue. INNs are free of proprietary rights and are the names used in scientific literature.
- Brand name. Proprietary, jurisdiction-specific, applies only to an authorised medicinal product. Research-grade material is not the branded product and should never be described by a brand name.
- Research-market names. Informal: TB-500, GHRP-6, BPC-157. Some began as development codes, some as descriptions. They are widely used, sometimes ambiguous, and rarely appear in primary literature in that form.
- Catalogue names. A supplier's listing name, which may combine any of the above. Alphex lists retatrutide as "GLP-3 (RT)" and states the INN, the development code and the CAS number on the specification, so there is no ambiguity about what is supplied.
Moving between them
The CAS number is the reliable bridge: it identifies the substance regardless of name. Look up a listing's CAS number and confirm it matches the name, molecular formula and molecular weight given. For literature searching, search on the development code and the INN together; a great deal of preclinical work predates the INN. See CAS numbers.
Where naming causes real problems
- Fragment versus parent. "TB-500" and "thymosin beta-4" are used interchangeably and are different molecules. See Tβ4 versus TB-500.
- Complex versus free peptide. "Copper peptide" may mean GHK-Cu or something else. See GHK versus GHK-Cu.
- Salt and modification not in the name. Amidated versus free acid, acetylated versus not, acetate versus TFA; none is implied by a common name. See sequence notation.
- Brand names on research listings. A supplier using a pharmaceutical brand name for a research reagent is making a medicinal presentation, with the legal exposure that implies. See MHRA and research peptides.
- Invented catalogue names. Legitimate as a listing label, misleading if they obscure identity. This is why Alphex publishes INN, code, CAS and sequence next to the catalogue name.
How to write it in a methods section
Name the compound by INN or the standard research name, give the CAS number, the sequence with modifications, the salt form, the supplier and batch number, and the purity with its method. That is unambiguous to any reader, and it is exactly what an Alphex specification table plus certificate provides. See record keeping.
Alphex research peptides are supplied for laboratory and in-vitro research by qualified researchers only. They are not authorised for human or veterinary use.
Research use only. Alphex products are supplied exclusively for laboratory and in-vitro research by qualified researchers. They are not authorised for human or veterinary use, and nothing in this note is advice on any such use.
Published 20 April 2026. Alphex reviews research notes when the testing method, the catalogue or UK guidance changes.