Retatrutide + Cagrilintide

1 Identity

Fixed-ratio two-component article, both components acylated: a 39-residue acylated incretin-class analog bearing two Aib residues, an alpha-methyl-leucine and a fatty-diacid side chain, co-lyophilized with a 32-residue amylin analog bearing an eicosanedioyl-gamma-glutamyl side chain, a Cys2-Cys7 intramolecular disulfide and a C-terminal amide. No metal center, no conjugate. The two components are retatrutide and cagrilintide, molecules of two different originating programs - cagrilintide is the amylin analog originated by Novo Nordisk - and each component's full identity lives on its own record and is cross-referenced from here rather than restated. No trade title for the pairing is in circulation; the record is named by its two components, and no observed title for anything of this description states a ratio or states which of the acylated forms is meant.

Sequence

Per component, cross-referenced. Retatrutide, reading from the N-terminus: Tyr1-Aib2-Gln3-Gly4-Thr5-Phe6-Thr7-Ser8-Asp9-Tyr10-Ser11-Ile12-(alpha-methyl-Leu)13-Leu14-Asp15-Lys16-Lys17-Ala18-Gln19-Aib20-Ala21, with the fatty-diacid side chain carried on a lysine and a C-terminal amide closing the chain; the complete residue list is on the component record. Cagrilintide: an eicosanedioic acid-gamma-Glu side chain on Lys1, then Cys2-Asn3-Thr4-Ala5-Thr6-Cys7 and onward to a C-terminal Thr-Tyr-NH2, with one intramolecular disulfide, Cys2-Cys7. Free-acid forms of either amidated component are specified impurities, not synonyms.

Molecular formula

Per component; a mixture has no combined formula and none is written. Retatrutide C221H342N46O68; cagrilintide C194H312N54O59S2. Retatrutide contains no sulfur and cagrilintide contains two, both in the disulfide, so a sulfur count assigns the two chains, and a free-thiol result on this article belongs on the certificate at or near zero rather than being absent from it. Counterion is a measured finding per component.

Average mass

Per component, on IUPAC 2021 abridged conventional atomic weights: retatrutide 4,731.421 Da; cagrilintide 4,409.07 Da. At a nominal 10 mg plus 10 mg fill, the 1.00 : 1.00 mass ratio is a molar ratio of 1.000 : 1.073, that is 2.11353 and 2.26805 micromol. The two components are within 323 Da of one another, which is the closest pairing in the blend set and is precisely why an unresolved envelope on a low-resolution instrument can be read as one broad species. No single blend molecular weight is printed.

Monoisotopic mass

Per component. Retatrutide 4,728.4718 neutral, [M+H]+ 4,729.4790. Cagrilintide 4,406.2515 neutral, with practical charge states [M+4H]4+ m/z 1,102.5702 and [M+5H]5+ m/z 882.2577. Both are worked from deconvoluted envelopes rather than from any single ion. The separations that matter are internal: des-acylation on either component, at the 598.778 Da eicosanedioyl interval on cagrilintide; the 0.984 Da amide-to-acid increment on both C-terminal amides; and the 2.016 Da reduced-versus-closed difference on the cagrilintide disulfide.

Salt / variant note

(1) the acyl state, on both components: intact against des-acyl, the latter being the characteristic impurity of an acylated analog and invisible in an area-percent figure. (2) the disulfide state on cagrilintide: closed Cys2-Cys7 against the reduced open chain at +2.016 Da, and against scrambled or intermolecular forms. (3) salt form: free base against acetate against trifluoroacetate, carried as separate items by institutional suppliers on the cagrilintide side. (4) the adjacent fixed combination: cagrilintide with semaglutide, known in the market as CagriSema, is a separate article on a separate record and a separate sponsor program. (5) ratio: no standard has been located.

2 Class & testing panel

Form

Fixed-ratio blend

Testing panel

P2 — panel definitionwith mandatory P3 additions as a union, run per component and never once for the vial. P2 is engaged twice and by two different acyl chemistries. P3 is engaged once, by retatrutide's Aib2, Aib20 and alpha-methyl-leucine13, which are achiral or alpha-alpha-disubstituted and carry no chiral limit but must be shown present by MS/MS. Cagrilintide adds a disulfide as an identity attribute in its own right - it is not a linear peptide and must never be specified as one. Two constraints belong on the face of the record. Aib is a common internal standard in amino acid analysis and is also a retatrutide residue twice over, so a default configuration is silently invalidated by the collision and would not surface as an out-of-specification result; the configuration is changed rather than accepted. And no authenticated reference standard for either component circulates outside its sponsor, which is why identity here rests on deconvoluted intact mass and MS/MS rather than on co-elution against a qualified standard

3 Primary sources & evidence

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

Published literature exists for each component and is graded on that component's record; both corpora are sponsor-generated clinical and preclinical program material, retatrutide's with a BLA submission announced for the first quarter of 2027 and cagrilintide's including its fixed combination with semaglutide. None of it is literature about this mixture of the two. No published study of the two components co-formulated at a fixed ratio, and no consensus specification for such a mixture, has been located - an absence of located evidence rather than a demonstration that none exists.

4 Storage & specification

Storage

Co-lyophilized solid at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light, with inert headspace. Two class properties drive the specification rather than decorate it: both fatty-diacid side chains make the article surface-active and prone to adsorptive loss in dilute solution, so low-adsorption labware is specified and recovery is demonstrated on the actual container-closure system; and the cagrilintide disulfide adds a thiol-disulfide exchange route, which the inert headspace and a low-pH solution condition are specified to suppress.

Shelf life

Provisional pending the company's own data; the blend runs its own protocol and inherits neither component study. The interval is dated on the acyl side chains and the disulfide rather than on gross purity: des-acylation at the 598.778 Da interval, hydrolytic loss of either C-terminal amide at 0.984 Da, and disulfide reduction or scrambling at 2.016 Da are the attributes that move first, and none of the three is visible in an area-percent figure.