What mass should a cagrilintide COA show?

PubChem lists cagrilintide as C194H312N54O59S2 with an average mass of 4409 g/mol and a monoisotopic mass of 4406.25 Da. A certificate should print the expected and the measured value and say which kind of mass it used. A measured value two hydrogen atoms heavier can mean the disulfide bridge is open, and a much larger difference points to a different molecule.

Why does cagrilintide need more than an identity test?

Several of its likely defects keep the same mass. A D-cysteine from racemisation during synthesis, or an iso-aspartyl form from asparagine deamidation, weighs what the target weighs, or within one mass unit of it. These show as separate peaks on HPLC. Identity tells you the molecule is cagrilintide; purity tells you how much of the sample is the correct form of it.

Is cagrilintide the same as CagriSema?

No. Cagrilintide is one peptide. CagriSema is the name used in published phase 3a trials for cagrilintide given together with semaglutide. A vial sold as cagrilintide alone should contain no semaglutide, and LC-MS can confirm that because their masses are about 300 units apart. A vial sold as the combination needs both peptides identified and each one measured separately.

Why might my cagrilintide test show less than the label?

Three common reasons. The vial may be underfilled. The label may count the weight of the salt, such as trifluoroacetate, rather than the peptide. Or part of the material may not have dissolved, which matters for an amylin analogue. A report that states peptide content, counter-ion content and how the sample dissolved lets you tell these apart.

One of the 30 compound testing profiles

Cagrilintide

Cagrilintide is a 37-amino-acid peptide (C194H312N54O59S2, average mass 4409 g/mol) with a C20 fatty diacid at its N-terminus and one disulfide bridge; a test should confirm that mass, check that the bridge is intact, and measure the amount against the label.

Cagrilintide is an investigational long-acting, lipidated analogue of the pancreatic hormone amylin (Kruse et al., Journal of Medicinal Chemistry, 2021), and the US FDA states it is not a component of any FDA-approved drug (FDA, unapproved GLP-1 drugs).

Test your cagrilintide

Identity card

Formula: C194H312N54O59S2
Average mass: 4,409 g/mol
Monoisotopic mass: 4,406.25 Da
Length: 37 residues
Modifications: N-terminal amine of Lys1 acylated with a C20 fatty diacid (19-carboxynonadecanoyl) through a gamma-glutamic acid; Disulfide bridge between Cys2 and Cys7; C-terminal amide (prolinamide)
Also sold as: Cagri, NN0174-0833
Sequence: KCNTATCATQRLAEFLRHSSNNFGPILPPTNVGSNTP
Note: PubChem gives the average mass only as a whole number (4409) and a monoisotopic mass of 4406.2515111 Da, recorded as 4406.25. The sequence, the Cys2 to Cys7 bridge and the terminal groups are from the FDA Global Substance Registration System (UNII AO43BIF1U8). PubChem's sequence string adds a leading X for the acylated gamma-glutamic acid, which shifts its residue numbering by one.

Source: PubChem CID 171397054, Cagrilintide, Global Substance Registration System, Cagrilintide (UNII AO43BIF1U8).

Compare the mass printed on a certificate with the values above. The mass checker explains charge states and which mass a lab usually reports.

What usually goes wrong with cagrilintide. Documented failure modes, with sources.

Amylin's tendency to form fibrils

Native amylin has a high propensity to form amyloid fibrils, which its developers describe as what makes it a challenging drug design starting point; cagrilintide was engineered as a stable analogue (Kruse et al., 2021). Aggregated material may not dissolve fully or may stick to surfaces, so it is missing from the solution the analyst runs and reads as a lower amount. A useful report notes how the sample dissolved and whether haze or particles remained.

The Cys2 to Cys7 bridge and cysteine racemisation

The ring is closed by a disulfide between Cys2 and Cys7 (GSRS, cagrilintide). Cysteine racemises readily during synthesis: in a published comparison under basic activation with the standard trityl protecting group, conventional synthesis gave 8.0% D-cysteine and synthesis at 80 degrees C gave 26.6% (Behrendt et al., Journal of Peptide Science, 2016). A D-Cys variant has the same mass as the target, so only chromatography separates it. An open bridge (two hydrogen atoms heavier) or a disulfide-linked dimer has a different mass and is caught by LC-MS.

Five asparagines that can deamidate

The sequence carries asparagine at positions 3, 21, 22, 31 and 35. Asparagine deamidates through a succinimide intermediate that gives a mixture of normal and iso-aspartyl forms, with racemisation along the way; in the same model study, replacing the glycine after asparagine with leucine or proline slowed degradation 33 to 50 fold (Geiger and Clarke, Journal of Biological Chemistry, 1987). Cagrilintide has no Asn-Gly pair. Each deamidation adds only +0.984 Da (Butré et al., Molecules, 2023), which a low-resolution intact mass can miss.

Counter-ions counted as peptide

Synthetic peptides are usually isolated as trifluoroacetate salts, the counter-ion count tracks the number of positive charges, and in one study trifluoroacetate reached 35% of the total weight of the peptide salts tested (Erckes et al., Pharmaceuticals, 2025). Cagrilintide has two arginines, a histidine and a lysine side chain that can pair with a counter-ion. A vial filled by weighing the salt holds less peptide than its label, even if every molecule in it is genuine.

What we check in Cagrilintide. Silent, with captions.

Which tests matter most

LC-MSConfirms the 4409 average mass, and shows an open disulfide, a dimer or a missing side chain as peaks of different mass.
HPLC-UVThe routine way to see same-mass variants such as a D-cysteine or iso-aspartyl form, which elute as separate peaks.
Peptide mappingConfirms the disulfide joins Cys2 and Cys7 and locates any deamidated asparagine.
Counter-ion contentMeasures trifluoroacetate or acetate so the amount result reflects peptide rather than salt.
Appearance and solubilityRecords whether the powder dissolved clear, which matters for an amylin analogue.

Reading cagrilintide results

PubChem gives the average mass only as a whole number, 4409, so a certificate quoting decimals took its reference value from somewhere else and should say where. Check that the expected mass was calculated with the disulfide closed: treating both cysteines as free thiols adds two hydrogen atoms and can make a correct sample look wrong, or the reverse. The mass checker computes average and monoisotopic masses from a sequence.

There is no approved cagrilintide product, so no originator material to compare against. Every amount result depends on the laboratory's reference standard; ask how that standard was itself identified and assigned a content. No common label amounts are listed because Tested.ph has not yet recorded cagrilintide listings.

Public Tested.ph results

No public cagrilintide records yet

Each public cagrilintide record will appear here with its identity, HPLC purity and measured amount against the label, once the first vial is tested.

FIG 13Amount against the label

Questions about testing cagrilintide

What mass should a cagrilintide COA show?: PubChem lists cagrilintide as C194H312N54O59S2 with an average mass of 4409 g/mol and a monoisotopic mass of 4406.25 Da. A certificate should print the expected and the measured value and say which kind of mass it used. A measured value two hydrogen atoms heavier can mean the disulfide bridge is open, and a much larger difference points to a different molecule.
Why does cagrilintide need more than an identity test?: Several of its likely defects keep the same mass. A D-cysteine from racemisation during synthesis, or an iso-aspartyl form from asparagine deamidation, weighs what the target weighs, or within one mass unit of it. These show as separate peaks on HPLC. Identity tells you the molecule is cagrilintide; purity tells you how much of the sample is the correct form of it.
Is cagrilintide the same as CagriSema?: No. Cagrilintide is one peptide. CagriSema is the name used in published phase 3a trials for cagrilintide given together with semaglutide. A vial sold as cagrilintide alone should contain no semaglutide, and LC-MS can confirm that because their masses are about 300 units apart. A vial sold as the combination needs both peptides identified and each one measured separately.
Why might my cagrilintide test show less than the label?: Three common reasons. The vial may be underfilled. The label may count the weight of the salt, such as trifluoroacetate, rather than the peptide. Or part of the material may not have dissolved, which matters for an amylin analogue. A report that states peptide content, counter-ion content and how the sample dissolved lets you tell these apart.

Sources

Kruse T et al. Development of Cagrilintide, a Long-Acting Amylin Analogue. J Med Chem. 2021;64(15):11183-11194, PubMed
FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss, US Food and Drug Administration
Global Substance Registration System, Cagrilintide, US FDA and NCATS
Behrendt R, White P, Offer J. Advances in Fmoc solid-phase peptide synthesis. J Pept Sci. 2016;22(1):4-27, Journal of Peptide Science (PMC)
Geiger T, Clarke S. Deamidation, isomerization, and racemization at asparaginyl and aspartyl residues in peptides. J Biol Chem. 1987, PubMed
Erckes V et al. Towards a Consensus for the Analysis and Exchange of TFA as a Counterion in Synthetic Peptides. Pharmaceuticals. 2025;18(8):1163, Pharmaceuticals (PMC)
Butré CI et al. Interlaboratory Evaluation of a User-Friendly Benchtop Mass Spectrometer. Molecules. 2023;28(6):2855, Molecules (PMC)
Garvey WT et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2025;393(7):635-647, PubMed

Last reviewed 6 Oct 2026.