Preloaded Autoinjector | Cagrilintide | 3ml Pen | 20mg

The cagrilintide pen is a preloaded 3ml research autoinjector holding the long-acting amylin analogue cagrilintide in solution at 20/3 mg/ml, giving 20mg in the device. Amylin analogues are engineered against their own tendency to form amyloid, so the question this format raises is whether a solution standing at 2-8°C for weeks stays monomeric.

Specification Table

What Changes When Cagrilintide Ships in Solution?

Putting a 4409 Da amylin analogue into water starts a competition between the monomer and the fibril, and unlike almost every other degradation route in peptide chemistry, the fibril weighs exactly what the monomer weighs.

Westermark and colleagues pinned amylin’s fibril-forming core to residues 20-29 in 1990, and every therapeutic amylin analogue since has been an argument with that stretch of sequence. Pramlintide replaced Ala25, Ser28 and Ser29 with proline, which cannot sit in a beta sheet. Cagrilintide keeps all three prolines, adds N14E, V17R and Y37P, then hangs a C20 diacid off a gamma-glutamyl spacer at the alpha-amine of Lys1. Kruse and colleagues (2021) call the result a stable, lipidated analogue. The engineering reduced the risk. It did not delete the sequence that causes it.

What follows from that for a device rather than a vial is specific. Fibrillation is nucleation-dependent, so it runs on time, temperature, agitation and above all on air-liquid interfaces, and a pen that travels, gets shaken in a bag and is actuated twenty times over a month supplies all four. It is also the one failure mode mass spectrometry cannot report: a fibril is the same molecule stacked, so intact-mass purity looks unchanged while material drains into a solid phase. The visible tell is faint opalescence or a gel-like thread, by which point the change is well advanced.

The lipid cuts both ways. A saturated C20 diacid cannot peroxidise, but it makes the molecule amphipathic by design so that it binds albumin in plasma, and the same amphipathicity drives it onto plunger elastomer, onto polypropylene and onto the air-liquid interface where nucleation begins. In a concentrated fill the loss to surfaces is small; in an assay dilution it can dominate, which is why low-binding tubes and a carrier protein belong in any protocol built from this device.

The slower chemistry is ordinary and largely invisible. Five asparagines (positions 3, 21, 22, 31 and 35) and Gln10 can deamidate, each adding 0.98 Da. On a 4409 Da molecule that is about 0.02 percent, at or below the resolving power of many benchtop instruments, so deamidation is detected by charge rather than by mass. None of the five asparagines is followed by glycine, which removes the fastest succinimide route, and the sequence contains no aspartate at all. The Cys2-Cys7 disulfide is the other watch point: it reduces at alkaline pH and with free thiols, and reduction opens a ring the fibril core is otherwise sterically discouraged from entering. Three routes are unavailable: the acylated N-terminus rules out pyroglutamate and diketopiperazine formation, no methionine means no oxidation there, and Tyr37 replaced by proline leaves no chromophore.

The only approved amylin analogue tells the rest. Pramlintide is sold as a 1000 microgram per millilitre solution at about pH 4.0 in acetate buffer with D-mannitol and 2.25 mg/ml metacresol, refrigerated, light-protected, never frozen, with a 30-day in-use period at up to 30°C, and its label forbids mixing with insulin. Two decisions there are instructive: the formulation sits at acidic pH, away from the neutral range where amylin analogues aggregate fastest, and it carries a preservative because a repeatedly punctured multi-dose solution needs one. Cagrilintide’s own formulation is not public, and in REDEFINE 1 it was not co-formulated with semaglutide at all: the two peptides came from a dual-chamber, single-dose pen and met only at injection. Garvey and colleagues do not say why, but semaglutide products sit near neutral pH and the approved amylin analogue does not.

Concentration and Increment Arithmetic for the Cagrilintide Pen

At 20mg in 3 ml the concentration is 20/3 mg/ml, which at 4409.07 g/mol works out as (20/3) divided by 4409.07 moles per litre: a 10 mg fill gives 3.333 mg/ml and 0.756 mM, a 5 mg fill gives 1.667 mg/ml and 0.378 mM.

A single 0.01 ml graduation carries 20/300 mg; ten of them carry 20/30 mg. At a 10 mg fill that is 33.3 micrograms and 333 micrograms, or 7.6 and 76 nanomoles.

Set that against the published amounts. Trial participants received 0.16 to 4.5 mg once weekly in phases 1b and 2, and 2.4 mg in phase 3; at a 10 mg fill, 2.4 mg is 0.72 ml. Receptor work runs orders lower, and reaching 1 nM from 0.756 mM needs a 756,000-fold dilution on a molecule that adsorbs to whatever it touches. The peptide dilution calculator handles the arithmetic; adsorptive loss across five serial steps is the part no calculator reports.

Does Cagrilintide Come in a Pen?

Cagrilintide does come in a pen: this preloaded 3 ml autoinjector holds the analogue in solution and sits in the catalogue beside the lyophilized 10mg vial, the 5mg vial and the co-supplied semaglutide combination.

The question “does cagrilintide come in a pen” usually arrives from someone who has read about the phase 3 programme and assumed the research material matches the clinical one. It does not. General format questions are covered on the preloaded autoinjector category page. What is specific to cagrilintide in pen form is that a multi-dose device extends the two exposures amylin analogues tolerate least: standing time and repeated agitation.

Cagrilintide Pen vs Vial: What Each Format Suits

The cagrilintide pen vs vial decision comes down to whether the work needs a fixed solution held for weeks or a fresh one made on the day, and for a fibril-prone amphipathic peptide the fresh one has a real argument behind it.

The pen suits repeated equivalent draws from one lot where preparation variance dominates the error. Weighing a lipidated peptide accurately and dissolving it without foaming are both harder than they look, and the device fixes a single fibrillation history rather than a new unknown at each reconstitution.

The vial suits anything quantitative. A solution made an hour before an assay has had no time to nucleate, its buffer and pH are chosen rather than inherited, and a fresh preparation is the only honest comparator for judging whether an older device has changed. Where adsorptive loss and unseen oligomer matter more than pipetting error, cagrilintide solution vs lyophilized is not a close call. The peptide pen versus vial article sets out the trade-offs common to the format; the cagrilintide autoinjector vs vial version is unusual because the format’s weakness, standing time in solution, points directly at this molecule’s known failure mode.

Cagrilintide Pen Storage and Handling

Cagrilintide pen storage is 2-8°C, protected from light and never frozen, the regime the pramlintide label specifies for the only amylin analogue anyone has taken through regulatory review.

Freezing is prohibited twice over. Ice-front concentration pushes peptide into a shrinking liquid volume at rising ionic strength, a standard way to nucleate amyloid, and each thaw renews the air-liquid interface. Separately, 3 ml of aqueous solution expanding inside a sealed glass cartridge cracks glass and displaces elastomer plungers.

Agitation is the handling variable that separates this compound from most others in the format. Do not shake, do not vortex, and do not transport the device loose; roll or invert gently where mixing is needed at all. Foam is the visible signature of an air-liquid interface renewed thousands of times a minute. Record the fill date, the date of first actuation and every excursion above 8°C with its duration, because no in-use period exists for this molecule in any solution and that history is the only evidence about the remaining contents. Pramlintide’s 30-day allowance belongs to a preserved, acidic, formulated product and does not transfer. The peptide storage and stability guide covers the general principles.

What the Product Record Does Not State

Four values are absent from the record, and for an aggregation-prone peptide the first two decide almost everything about how the device ages.

Solution pH is not stated. Amylin analogues aggregate fastest near their isoelectric point, cagrilintide’s pI is unpublished and estimated between 7 and 9, and the approved analogue in this class is formulated at pH 4.0 rather than at neutrality. A fill at pH 7 and a fill at pH 4 are different products in stability terms.

The excipient system is not stated: whether a preservative is present, whether a surfactant such as polysorbate 20 occupies the air-liquid interface, and what the buffer is. All three change the aggregation rate, and a surfactant at formulation levels is not inert in cell culture. The salt form is not stated either, and trifluoroacetate carried over from purification has measurable effects at the concentrations a millimolar stock delivers. Nor is the fill date. Ask for it; the real-time stability data behind it does not exist for this compound in any format.

Verifying the Cagrilintide Pen and Confirming the Contents

Inspect the solution against both a light and a dark background before each draw: it should be clear, colourless and free of particulate, and any opalescence, haze, faint bluish scatter or thread-like material is the first visible evidence of self-association rather than a cosmetic fault.

Confirming what is in solution needs three separate measurements, because no single one covers the failure modes. Concentration cannot be read at 280 nm: with Tyr37 replaced by proline the molecule has neither tryptophan nor tyrosine, so a reading there reports excipient or noise. Use reversed-phase HPLC at 214 nm against a standard prepared the same day from a lyophilized vial, which gives concentration and the chromatographic purity of the monomer together.

Aggregate is a size question, not a mass question, so it needs size-exclusion chromatography or dynamic light scattering. Both report the soluble oligomer that a monomer peak can miss and that intact-mass analysis cannot see at all. Intact mass still earns its place for the covalent chemistry: a 4406.25 Da monoisotopic parent, a 0.98 Da gain per deamidated residue, and a 2 Da gain if the Cys2-Cys7 disulfide has been reduced.

What Does the Cagrilintide Literature Actually Report?

Every human result published for this molecule comes from Novo Nordisk’s own clinical programme using the sponsor’s clinical material, across one phase 1b study, one phase 2 study and two phase 3a studies totalling more than 5,400 randomised participants.

Enebo and colleagues (2021) ran the phase 1b study, NCT03600480, in 96 participants for 20 weeks: 0.16 to 4.5 mg given with semaglutide 2.4 mg produced mean body-weight changes of -15.7% at 1.2 mg and -17.1% at 2.4 mg, against -9.8% for semaglutide with placebo. Lau and colleagues (2021) reported the phase 2 study, NCT03856047, with 706 participants randomised to 0.3 to 4.5 mg weekly, 99 to liraglutide 3.0 mg daily and 101 to placebo; at week 26 the analogue arms showed -6.0% to -10.8%, liraglutide -9.0% and placebo -3.0%.

REDEFINE 1 (Garvey 2025, NCT05567796) randomised 3,417 adults without diabetes for 68 weeks and separates the combination from its parts: -20.4% for the combination, -14.9% for semaglutide alone, -11.5% for the amylin analogue alone in 302 participants and -3.0% for placebo, with 53.6% of the combination arm reaching a loss of 20% or more against 1.9% on placebo. REDEFINE 2 (Davies 2025, NCT05394519) ran the combination in 1,206 adults with type 2 diabetes and reported -13.7% against -3.4%, with 73.5% reaching HbA1c of 6.5% or below against 15.9%. A fourth study against tirzepatide was reported in February 2026 to have missed its primary endpoint; that comes from a secondary source and has not been re-verified.

The gaps are as specific as the results. Preclinical potency, selectivity and fibrillation measurements sit behind a paywall in Kruse 2021. No human data exist for any material other than the sponsor’s, and there is no public in-use stability study of any solution of this compound, no monotherapy outcome beyond 68 weeks, and no paediatric or cardiovascular-outcome data.

What Is the Cagrilintide Half Life?

The cagrilintide half life in humans is 159 to 195 hours, or about 6.6 to 8.1 days, with a median time to maximum concentration of 24 to 72 hours after subcutaneous injection, measured by Enebo and colleagues in the 2021 phase 1b study.

That figure is why the compound is given once weekly, and it comes from the C20 diacid: the lipid binds albumin, which keeps the peptide in circulation instead of clearing it. Semaglutide measured 145 to 165 hours in the same study, so the amylin analogue outlasts the incretin it is paired with. The number says nothing about how long the compound survives in a cartridge, which is a chemical question with no published answer.

What Is the Safety and Regulatory Position?

Cagrilintide is investigational everywhere: no approval from the FDA, EMA, PMDA, TGA or Health Canada, and an NDA for the once-weekly combination of cagrilintide 2.4 mg with semaglutide 2.4 mg for weight management was filed on 18 December 2025 with no decision public in sources reachable in September 2026.

The adverse-event record comes from the same trials as the efficacy figures. Lau 2021 reported gastrointestinal disorders in 41-63% of recipients against 32% on placebo, and nausea in 20-47% against 18%. In REDEFINE 1 the combination arm against placebo showed gastrointestinal events in 79.6% against 39.9%, serious adverse events in 9.8% against 6.1%, discontinuation for adverse events in 5.9% against 3.5%, injection-site reactions in 12.2% against 3.0%, gallbladder disorders in 4.1% against 1.0%, and two deaths against none, with more fatigue, dizziness, alopecia and allergic reactions.

The compound is not on the FDA section 503A bulk-substance list and not in Category 1 or Category 2 of the interim lists (FDA page updated 22 April 2026), and it is not a component of any approved drug, so no lawful basis exists for compounding it from bulk in the United States. No WADA entry was found under this name, though the 2026 list itself could not be opened, so the position is unconfirmed.

Published Literature

The entries below concern the compound and the amylin biology behind it; nothing has been published on this delivery format.

1. Kruse T, Hansen JL, Dahl K, et al. Development of Cagrilintide, a Long-Acting Amylin Analogue. Journal of Medicinal Chemistry. 2021;64(15):11183-11194. DOI: 10.1021/acs.jmedchem.1c00565. PMID: 34288673
2. Enebo LB, Berthelsen KK, Kankam M, et al. Safety, tolerability, pharmacokinetics, and pharmacodynamics of concomitant administration of multiple doses of cagrilintide with semaglutide 2.4 mg for weight management: a randomised, controlled, phase 1b trial. The Lancet. 2021;397(10286):1736-1748. DOI: 10.1016/S0140-6736(21)00845-X. PMID: 33894838
3. Lau DCW, Erichsen L, Francisco AM, et al. Once-weekly cagrilintide for weight management in people with overweight and obesity: a multicentre, randomised, double-blind, placebo-controlled and active-controlled, dose-finding phase 2 trial. The Lancet. 2021;398(10317):2160-2172. DOI: 10.1016/S0140-6736(21)01751-7. PMID: 34798060
4. Garvey WT, Blüher M, Osorto Contreras CK, et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2025. DOI: 10.1056/NEJMoa2502081. PMID: 40544433
5. Davies MJ, Bajaj H, Broholm C, et al. Cagrilintide and Semaglutide in Adults with Overweight or Obesity and Type 2 Diabetes. New England Journal of Medicine. 2025. DOI: 10.1056/NEJMoa2502082. PMID: 40544432
6. Hay DL, Chen S, Lutz TA, et al. Amylin: Pharmacology, Physiology, and Clinical Potential. Pharmacological Reviews. 2015;67(3):564-600. DOI: 10.1124/pr.115.010629
7. Westermark P, Engström U, Johnson KH, et al. Islet amyloid polypeptide: pinpointing amino acid residues linked to amyloid fibril formation. Proceedings of the National Academy of Sciences USA. 1990;87(13):5036-5040. DOI: 10.1073/pnas.87.13.5036

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