Retatrutide

1 Identity

Acylated synthetic lipopeptide, not a plain peptide: a 39-residue single-chain backbone of GIP-analogue design, C-terminally amidated, carrying two alpha-aminoisobutyric acid substitutions and one alpha-methyl-leucine, with a C20 fatty diacid conjugated to a lysine side chain through a gamma-glutamate and a single AEEA unit. The sponsor's class designation is "GIP/GLP-1/glucagon receptor triple agonist"; that phrase is recorded as nomenclature and is not restated anywhere in this record as a property. Gray-market shorthand including "triple-G", "GGG" and "GLP3-R" is recorded so that those listings can be recognized; the company's records, certificates, labels and invoices use the INN and never a code word.

Sequence

Tyr1-Aib2-Gln3-Gly4-Thr5-Phe6-Thr7-Ser8-Asp9-Tyr10-Ser11-Ile12-(alpha-methyl-Leu)13-Leu14-Asp15-Lys16-Lys17-Ala18-Gln19-Aib20-Ala21-Phe22-Ile23-Glu24-Tyr25-Leu26-Leu27-Glu28-Gly29-Gly30-Pro31-Ser32-Ser33-Gly34-Ala35-Pro36-Pro37-Pro38-Ser39-NH2, with the Lys17 side-chain N-epsilon bearing (AEEA)-(gamma-Glu)-(C20 diacid). One AEEA unit, not two. Aib at positions 2 and 20 only; position 13 is 2-methylleucine, a different non-proteinogenic residue. Three non-proteinogenic positions, one acylation site, one C-terminal amide — five features, every one of which a plain-peptide specification is blind to.

Molecular formula

C221H342N46O68

Average mass

4731.421 Da from C221H342N46O68 on IUPAC 2021 abridged conventional atomic weights, and the basis is stated on the face of the mass because on this molecule the atomic-weight table is the whole of the published spread. The pre-2021 table (C 12.0107, H 1.00794, N 14.0067, O 15.9994) returns 4731.347 for the same formula. Two supplier figures circulate for that one formula, 4731.42 and 4731.33: the first sits on the 2021 table and the second on the older one, and there is no discrepancy between them beyond the table. On a 4.7 kDa molecule a 0.07 Da table difference is 15 ppm and is not a defect; a 14 Da difference would be a missing methyl group and is.

Monoisotopic mass

4728.4718 Da neutral; [M+H]+ 4729.4790. At this mass the measurement that matters is the deconvoluted multiply-charged envelope, and the identity question requires NLT 30,000 resolving power, because the C-terminal amide versus free acid difference is 0.984 Da and is simply invisible below that.

Salt / variant note

Single molecule under this name in the legitimate channel; the substitution risk is other incretin articles, and every one of them separates by arithmetic on one calculator. Semaglutide C187H291N45O59, average 4113.641, monoisotopic 4111.1154. Tirzepatide C225H348N48O68, average 4813.527, monoisotopic 4810.5249. Liraglutide C172H265N43O51, average 3751.262, monoisotopic 3748.9465. A certificate issued under the name retatrutide reporting 4113.6, 4813.5 or 3751.3 is certifying a different, approved, patented molecule, and no purity figure is relevant to that fact. Within-molecule variants, each checkable against the supplier's own declared parent mass with no reference standard in hand: a C-terminal free acid instead of the specified amide is exactly plus 0.984 Da and is invisible below about 30,000 resolving power; alanine substituted for Aib at position 2 or 20 is minus 14.0157 Da monoisotopic per position, minus 28.03 for both — Aib is non-proteinogenic, costs more and couples worse than alanine, and substituting it is the cheapest way to make something that resembles the molecule; leucine for alpha-methyl-leucine at position 13 is the same minus 14.0157 Da, which is why an instruction to look for Aib at 13 sends the laboratory hunting the wrong residue at the right delta. Full des-acylation — removal of the entire (AEEA)-(gamma-Glu)-(C20 diacid) side chain — gives the backbone C190H288N44O59 at 4132.643 average and 4130.0888 monoisotopic, an interval of 598.778 Da average and 598.383 Da monoisotopic. That interval is the only detection tool for des-acylation on offer here, and it holds only if the AEEA count is right: an identity written with two AEEA units instead of one puts the interval at 743.94, one 145.16 Da AEEA unit too large, and sends the laboratory looking for a species that is not there. Acylation at the wrong lysine — Lys16 rather than Lys17 — is a positional isomer at the identical formula and identical exact mass, detectable only by peptide mapping.

2 Class & testing panel

Form

Single article

Testing panel

P2 — panel definitionwith mandatory P3 additions

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

A large, active, sponsor-controlled clinical development program exists, and its identifiers are recorded by study type without restating any reported outcome. Peer-reviewed: Coskun T et al., Cell Metab 2022, PMID 35985340, preclinical characterization with early human proof of concept; Urva S et al., Lancet 2022, PMID 36354040, phase 1b human study; Jastreboff AM et al., NEJM 2023, PMID 37366315, phase 2 randomized human trial in obesity; Sanyal AJ et al., Nat Med 2024, PMID 38858523, phase 2a randomized human trial in MASLD; Bajaj HS et al., Lancet 2026, PMID 42250575, phase 3 randomized human trial in type 2 diabetes. Registered phase 3 trials in the TRIUMPH program include NCT05929066 (n=2,339, 80 weeks) and NCT05929079 (n=1,152); as of August 2026 the pivotal obesity results are available chiefly as company topline releases and conference presentations rather than peer-reviewed publications, and that distinction is stated for each item on the research page. A rodent study exists at PMID 40094000. The entire human evidence base belongs to the sponsor and describes investigational material made under an approved application — not any article sold in the research-chemical market. No independent, non-sponsor characterization of research-market "retatrutide" exists in the peer-reviewed literature: no published identity confirmation, no impurity profiling, no stereochemical analysis. A buyer holding a gray-market vial has no published basis for believing it contains the compound the clinical literature describes.

4 Storage & specification

Storage

Lyophilized powder at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light. The C20 fatty-diacid side chain makes the article surface-active and prone to adsorptive loss in dilute solution, which is why it is supplied and stored as the lyophilized solid.

Shelf life

The retest interval is dated on the acyl side chain rather than on gross purity. The two attributes that move first on an acylated incretin analogue are des-acylation at the 598.778 Da interval and hydrolytic loss of the C-terminal amide at 0.984 Da, and neither is visible in an area-percent figure, so both are trended by name and they, rather than a purity number, govern the date each container carries.