Our peptides are preserved to the gold standard for oxygen-sensitive drugs
We wanted the best protection that exists for sensitive peptides, so we built it. Our vials are evacuated under vacuum, backfilled with 99.999% argon, and sealed above atmospheric pressure — three full cycles of it before the stopper ever seats. Traditionally this method is found only on the most expensive pharmaceuticals, because of the added expense: sensitive biologics, vaccines, and a short list of drugs that simply cannot survive contact with air.
The point of all of it is one outcome: from the day it is sealed to the day it is empty, no room air ever enters the vial. Not filtered room air. None.
Glass does not collapse. To take liquid out, something has to go in.
That is the problem every multi-dose vial has, and the standard solution — printed in every set of instructions — is to draw an equal volume of room air into the syringe and inject it first. You do that once per dose, for the life of the vial. So the honest way to compare two vials is to ask a single question:
How much room air ends up inside, by the last dose?
A millilitre pushed in for every millilitre drawn out — so by the last dose the vial has taken in its own volume in room air. That air is roughly 21% oxygen and it is not sterile: it carries whatever bacteria, mould spores, skin cells and dust were in the room. Every bit of it sits against your product for the rest of the vial's life, and the last dose is breathing all of it.
Because the vial is sealed under argon above atmospheric pressure, you never have to put anything in. Insert the needle and the vial pushes liquid into the syringe for you. The gas inside can only ever travel outward.
As doses are drawn, that internal pressure falls and eventually sits slightly below atmospheric. That is expected and by design — the argon charge is sized so it never gets deep enough to fight the syringe or strand liquid in the vial. At no point is air used to make up the difference.
The same process protects everything we produce
Dry peptide vials. Bacteriostatic water. Oil-based injectables. Pen cartridges. All of it runs through the same purge, and that is not a convenience — it is the reason the method was worth building.
Vacuum alone can only ever protect a dry powder
Pull a real vacuum on a vial of liquid and the liquid boils. Water boils at room temperature once you drop below about 24 torr, well above the pressure a proper evacuation reaches. Long before that, dissolved gas comes out of solution and volatile components — the benzyl alcohol that makes bacteriostatic water bacteriostatic, for one — begin stripping out of the formulation. You cannot evacuate a filled liquid vial without changing what is in it.
This is the quiet limitation behind vacuum-only packaging, and it is why the technique appears almost exclusively on freeze-dried products. It has nothing to offer a liquid, an oil, or a cartridge.
A pen cartridge cannot be vacuum-protected at all, and the reason is structural rather than incidental. Its piston is free to slide — that is the entire point of the design, since the piston has to advance as drug leaves. Apply vacuum to a cartridge and you do not evacuate it. You just pull the piston down the barrel. There is no pressure differential to hold, because the cartridge resolves any differential by moving.
Argon displacement has no such limit. Because it works at and above atmospheric pressure rather than below it, nothing in the container is asked to hold a vacuum it structurally cannot hold. The same purge that protects a dry cake protects an aqueous solution, an oil, and a cartridge with equal effectiveness.
The premium delivery formats — GLP-1 pens, HGH, insulin — sidestep the headspace problem in the only other way it can be sidestepped: the piston advances as drug leaves, so the reservoir simply gets smaller and nothing enters to replace what was used. That works, but it is a purpose-built device rather than something a conventional vial can be made to do. A standard stoppered vial has no answer to this at all, which is why so few even try.
Oils need this as much as peptides do
Carrier oils are not inert. The unsaturated fats in them oxidise on contact with air, forming peroxides — the same chemistry as a bottle of cooking oil going rancid, just slower and invisible. Those peroxides then sit in the vial with the active ingredient for the rest of its shelf life. An argon blanket over an oil-based injectable is doing exactly the job it does over a peptide solution.
One system, validated once, applied to everything that leaves here. No product line gets the cheap version because it was inconvenient to protect.
What an ordinary vial asks you to do
Glass does not collapse. So when you pull liquid out, something has to take its place — and the standard technique, printed in every set of instructions, is to draw an equal volume of room air into the syringe and push it in first. That air is about 21% oxygen and it is not sterile. You do it once per dose, ten or twenty or thirty times, over the life of the vial.
What the oxygen does to the peptide
Peptides carrying methionine, cysteine or tryptophan oxidise on contact with it. The damage is invisible — no cloudiness, no colour change, just less of the molecule you paid for by the time you reach the bottom of the vial.
What it does to the stabilisers
The surfactants that keep peptide from sticking to glass and unfolding at the liquid surface oxidise too. In a controlled comparison, vials with an ordinary air headspace lost half their surfactant content in two weeks under accelerated conditions, while vials sealed under inert gas lost none. US Patent 7,387,623
Worse, that oxidation produces peroxides, and those peroxides then attack the peptide's own vulnerable residues. Air in the headspace does not just expose the drug — it builds a second attacker inside the vial. Surfactant oxidation study And every one of those air pushes drags whatever is on the stopper face and in the room down the needle track.
Vacuum, fill, vacuum, fill, vacuum, fill
Every vial runs three complete purge cycles before the stopper is ever seated. The repetition is the point. One flush leaves pockets behind; three cycles of pulling everything out and putting only argon back drives the residual down each pass until there is effectively nothing left to find.
- 01
Vacuum
The vial is drawn down under vacuum, which pulls out ambient air and moisture together. That second part matters as much as the first. Water drives hydrolysis in a dry peptide cake and carries dissolved oxygen in a liquid, and a gas flush does nothing about it — flushing only dilutes what is already there and leaves trapped pockets in the corners and in the cake itself. Evacuating removes them.
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Argon backfill
The vacuum is broken with 99.999% argon. Because the oxygen is already gone, the argon fills the space undiluted rather than mixing into whatever remained.
We use argon rather than nitrogen for one reason: it is heavier than air. Argon has a molar mass of about 40, against air's 29 and nitrogen's 28 — so at the same temperature and pressure argon is roughly 38% denser than the air it is displacing, while nitrogen is very slightly lighter. A gas lighter than air rises, channels out of an open vessel, and dilutes the oxygen rather than displacing it. A gas heavier than air sinks in and pushes the oxygen up and out ahead of it.
Winemakers settled this argument decades ago. Nitrogen is the cheaper cellar gas, but its recognised drawback for blanketing is exactly this: it mixes easily with air and dissipates quickly, so it has to be purged through in volume rather than simply laid over the surface. Argon is what gets used when a wine has to sit protected in a partly empty tank or an open bottle. WineMaker The effect is measurable enough that industrial purging equipment is engineered around it — heavy-gas displacement reaches lower residual oxygen than a light gas can. US Patent 5,682,723
Argon is a tracer as well as a blanket
Air is already 78% nitrogen. Argon is under 1%. You cannot look at a nitrogen headspace and know whether the purge worked, because a vial full of untouched room air is also mostly nitrogen. Argon in a sealed vial can only have got there one way: we put it there. A vial that still reads argon is a vial that has never taken in room air — which makes headspace gas analysis a non-destructive container-integrity check rather than merely a purge record.
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Repeat, then seal above atmosphere
After the third cycle the vial is left with an argon charge above atmospheric pressure, and the stopper is seated and crimped. Most sealed vials close at or slightly below atmospheric, which is fine for a product used once. Ours close above it, so over a multi-dose vial's life the pressure gradient points outward — a needle track, a slow reseal or a micro-leak can only vent argon out.
No vial and stopper are perfect. There are always microscopic imperfections in the glass finish, the stopper face and the crimp, and every needle entry adds more. A vial held under vacuum turns every one of those into an inlet: the pressure difference actively pulls outside air through them for the entire life of the product. Fill the same vial with argon above atmospheric and the physics invert. An imperfection vents a trace of argon instead of admitting air — and unlike a vacuum, which gets more dangerous the better it is, a positive charge fails safe.
The practical result you notice on the first dose: you never push air into one of our vials. Uncap, insert the needle, and the vial fills the syringe for you.
Where else you will find this
Inert-gas sealing is not a novelty we invented. It is reserved for drugs where oxidation is the thing that ruins them — and it is almost entirely absent from the compounded and research market, because it is slow and expensive to do properly.
ELCYS — cysteine hydrochloride injection
The closest published analogue to our own process in an FDA-approved product. An argon overlay holds dissolved oxygen at or below 1 ppm through mixing, oxygen is stripped again before filling, and headspace oxygen is then removed with a series of argon flushes and vacuum pulses. Cysteine is among the residues most vulnerable to oxidation — the same chemistry that threatens peptides.
Preservative-free catecholamines
Noradrenaline, dopamine and dobutamine solutions formulated without antioxidants are packaged under argon to a headspace specification holding residual oxygen at or below 4%.
Epinephrine injection, USP
The approved label states outright that the contents are sealed under nitrogen, and warns that the drug deteriorates rapidly on exposure to air — turning pink, then brown, as it oxidises. Most drugs do not show you the damage. This one does.
Secukinumab (Cosentyx)
An inert-gas headspace purge paired with a sacrificial antioxidant in the formulation. Containers held below roughly 12% headspace oxygen tested measurably more stable than unpurged ones. That two-layer approach — inert gas outside, antioxidant inside — is the principle we build to.
Freeze-dried biologics and vaccines
Lyophilised drugs are dried under vacuum and that vacuum is broken with inert gas before the stopper ever seats. FDA inspection guidance treats the backfill gas system as standard equipment requiring its own validation.
Technetium-99m diagnostic kits
An entire drug class sealed this way. DMSA and MYOVIEW kits are freeze-dried and then sealed under nitrogen, because the stannous reducing agent inside is destroyed on contact with oxygen. These are among the few products whose FDA-approved instructions tell you never to inject air — you withdraw gas from the headspace instead.
Lidocaine with epinephrine
The label identifies specific product lists whose headspace is nitrogen gassed. Even with an antioxidant and a chelator already in the formula, the manufacturer still removes the oxygen — the excipients and the gas do different jobs, and the good products use both.
Calcitriol injection
Compounded under nitrogen in a glove bag, filled under nitrogen with in-line flushing, then loaded into a lyophiliser purely to exchange the headspace completely before the stoppers are seated — so the vials are never exposed to open atmosphere at any point. Amber glass on top of that.
So why is not everything packaged this way?
Cost, and only cost. There is no technical argument against it — nobody claims oxygen is good for a peptide. Running a vacuum-and-backfill cycle means slower line speed, a qualified gas system with its own validation, headspace verification, and argon at several times the price of nitrogen. Every one of those is a line item, and every line item has to be justified against the specific molecule in the vial. For a stable small-molecule drug the honest answer is that it is not worth it, so major manufacturers skip it — not out of ignorance, but because the maths does not work on a product that was not going to oxidise anyway.
Peptides are not that product. They are exactly the case where the maths works, and they are also the category where almost nobody bothers to run it.
The gas is only half of it
A perfect headspace around a badly formulated solution buys you very little. Everything in our vehicle is there to do one specific job, and nothing is in there as filler.
There is no house recipe. Every peptide gets its own formula, developed for that molecule. What follows is the toolkit we select from — not a list of what is in every vial. That distinction is the whole difference between formulating and filling: a single vehicle poured over everything in a catalogue is fast and cheap, and it will be wrong for a meaningful fraction of what goes into it.
Amorphous glass former
Works two ways at once. It hydrogen-bonds directly to the peptide surface, standing in for the water shell removed during drying — and it sets into a rigid amorphous glass that immobilises the molecule so degradation reactions physically cannot proceed. In solution it holds the folded shape through pressure changes and fluid movement.
Interfacial surfactant
Reaches glass, syringe barrel and every air-liquid boundary faster than the peptide can, so the peptide never touches a bare surface and never unfolds at an interface.
Buffer system, adjusted to target
Every peptide has a narrow pH band where it is most stable and most soluble. We buffer to that band and verify the adjustment before fill, so the pH is a specification rather than an accident.
Sacrificial oxidation target
Any oxidant that does appear finds something easier to attack than your peptide. The excipient is consumed instead of the active — the same two-layer principle used alongside an inert headspace in approved biologics.
The seal is not the only thing standing between your peptide and the room. The pressure gradient is standing there too, pointed the right way.
How the lab is built