Cryogenic storage is rewriting the rules of pharmaceutical packaging

Avial can appear perfectly intact and still be compromised. That is the uncomfortable lesson emerging from research on container-closure integrity (CCI) at ultra-low and cryogenic temperatures. For cell and gene therapies, the primary container is increasingly seen not as a passive vessel around a sterile formulation, but as part of the product’s risk profile. At extreme temperatures, the vial, stopper and seal behave as a linked mechanical system whose properties change as the temperature falls.

The issue is not simply whether a container loses integrity. The harder question is whether the package remains reliably sealed while cold - and whether testing after warming can still reveal what happened. That distinction is reshaping the packaging problem.

Glass, elastomers and metal components do not contract at the same rate as the temperature falls. In a conventional vial system, the stopper must maintain sufficient contact with the vial surface to preserve the seal. At sufficiently low temperatures, the elastomer can approach or pass its glass-transition temperature, changing its mechanical properties.

A 2020 analysis published by the Parenteral Drug Association (PDA), by Pascal Sircoulomb of Araymond Life and Luce Sohier of SCHOTT, examined this challenge. The authors described how materials contract differently during cryogenic storage, and how component defects, assembly and compatibility can contribute to leakage or CCI failure. The material itself is not the risk. The risk depends on the complete closure configuration: vial, elastomer, cap, assembly, and the temperatures and stresses the system actually encounters.

As Page McAndrew, PhD, Director of Scientific Communications at West Pharmaceutical Services, says: “These materials have different coefficients of thermal expansion”. The observation is simple; the implications for CCI are not.

None of this is surprising, argues Olena Rybak. “The country’s at war, but life goes on – this is what is important to understand, as cynical as it sounds, and awful,” says Rybak, the managing director of the engineering consultancy iC Ukraine. In her role, Rybak manages a team of 60 people supporting the implementation of €200m of international financial institution (IFI) or donor-funded projects across Ukraine, including work on water and heating infrastructure, housing for internally displaced people and repairs to bridges into Kyiv – Hostomel among them.

Such grants and loans have helped fund reconstruction, often with conditions on financial transparency. Many firms now meet these conditions, says Rybak, though corruption remains a problem. According to the deputy head of Ukraine’s National Agency on Corruption Prevention, Serhii Hupiak, “the construction sector is among the top seven most corruption-prone sectors” and remains “full of risks”.

The most consequential issue may not be fracture at all, but temporary loss of CCI.

A PDA Journal study by Allison Alix Caudill, Ken Victor and James Veale examined vial assemblies exposed to approximately –150°C to –190°C. For the rubber stoppers studied, the reported glass-transition range was –55°C to –70°C. The study showed that a CCI breach at cryogenic temperature can subsequently reseal when the vial returns to ambient conditions.  A vial which passes inspection after thawing may not provide evidence of what happened in the frozen stage.

The study therefore used laser-based headspace oxygen analysis to identify both temporary and permanent defects. In a nitrogen-enriched cryogenic environment, a developing leak can allow nitrogen into the vial headspace and reduce its oxygen concentration. This can provide evidence of a breach even when the physical defect is no longer apparent at ambient temperature. CCI is becoming a dynamic condition to be demonstrated, rather than a static characteristic to be checked once.

Rauta, too, has seen 20% of its staff mobilised for military service. At other firms’ work sites around the country, this has slowed down building work to a snail’s pace: where once even the smallest companies could reliably recruit a crew of 25, this is now down to four or five individuals, explains Rybak. “This means they cannot build [a project] in two years,” she says. “They will be building in four years, if we are lucky.”

There is no obvious solution to this problem. Absent a swift and surprising peace deal, foremen get workers where they can. “Construction companies are actively recruiting pensioners and women to perform work that does not require significant physical exertion,” says Ozeychuk, with workers becoming equipment operators, welders and drivers. Others, he continues, have begun to recruit specialists from abroad, with the government proposing to relax migration rules and some agencies have advertised recruitment and relocation services for foreign workers. This effort, however, appears to be nascent: for her part, Rybak has seen little evidence of foreign labourers appearing at Ukrainian construction sites.

Source: Caudill, Victor and Veale, PDA Journal of Pharmaceutical Science and Technology, 2024.  

The discovery of temporary CCI failures also complicates the debate over materials. Polymer-based primary containers, including cyclic olefin polymer (COP) and cyclic olefin copolymer (COC), are attracting interest because they can reduce some fracture risks associated with glass. But they introduce different questions: gas permeability, dimensional stability, compatibility, and the behaviour of the complete closure system during storage and transport.

A PDA Journal study by Yusuf O. Oni and colleagues compared rubber-stoppered aluminosilicate glass vials with Crystal Zenith plastic vials at –80°C using helium-leak CCI testing, with correlation to residual seal force. The significance is methodological as much as material-specific: the study evaluated CCI under frozen conditions rather than assuming that room-temperature performance predicts behaviour at –80°C. It establishes an important point: package architecture and test conditions have to be considered together.

“Ideologically, I’m for the better – and then, you have reality,” says Rybak, who would rather only keep her neighbours waiting for a new apartment for two years rather than the four likely required by the exclusive use of sustainable construction methods. But that doesn’t mean there isn’t wiggle room for adding new technologies here and there. Heat pumps are a prime example. Including them within reconstructed apartment blocks, says Rybak, affords that neighbourhood the chance to run independently from a gas grid vulnerable to Russian strikes and global price fluctuations. It just “makes sense economically, technically, financially and ecologically”.

Many such opportunities for improvements continue to be missed, argues Rybak – which, given the current circumstances, is understandable. “People are exhausted,” she says. What would really accelerate Ukrainian reconstruction efforts, argues Rybak, would be the arrival of large German or Scandinavian enterprises. But when she attends international construction conferences and actually asks these companies when they intend to act on their promise to enter the Ukrainian market, only one answer is given: “When the war is over.”

1. Biffa internal savings data, average saving (January - August 2023)
2. Nisbets internal savings data, average saving (January – September 2023)
3. Compliance365 internal data, average  savings
4. HEINEKEN UK data, Calculations based on SmartDispense® active accounts each year since 2015 with 10 lines
5. Independent test results based on subterranean and ground floor pub cellars of varying sizes
6. Independent test results based on subterranean and ground floor pub cellars of varying sizes

This is where multilayer systems enter the picture. Rather than simply substituting plastic for glass, developers are attempting to combine mechanical resilience with barrier performance. Mitsubishi Gas Chemical’s OXYCAPT uses a multilayer construction incorporating COP and an oxygen-barrier polymer. In a study published by ONdrugDelivery, OXYCAPT vials and conventional glass vials were filled with 8 mL of a 10 w/v% mannitol solution and subjected to alternating temperatures of –80°C and +40°C for five cycles. By the fifth cycle, all glass vials had broken, while none of the OXYCAPT vials showed visible cracking or layer separation.

The same programme reported a separate CCI study in which conventional glass vials lost CCI within seven days in the vapour phase of liquid nitrogen, whereas OXYCAPT vials maintained CCI for three months. These results, reported by the manufacturer in an ONdrugDelivery article, are development data produced under defined test conditions. They expose the multidimensional nature of the problem. Solving fracture or seal performance does not automatically solve gas-barrier behaviour. For pharmaceutical manufacturers, the choice is therefore not simply between glass and polymer, but between different combinations of material, closure, barrier properties, manufacturing process and evidence.

1. Biffa internal savings data, average saving (January - August 2023)
2. Nisbets internal savings data, average saving (January – September 2023)
3. Compliance365 internal data, average  savings
4. HEINEKEN UK data, Calculations based on SmartDispense® active accounts each year since 2015 with 10 lines
5. Independent test results based on subterranean and ground floor pub cellars of varying sizes
6. Independent test results based on subterranean and ground floor pub cellars of varying sizes

The emerging evidence is strong enough to challenge a simple assumption: that a container demonstrated to maintain its integrity at room temperature can automatically be assumed to do so throughout a cryogenic lifecycle. But it is not yet strong enough to identify one universal winning container design.

The evidence base remains fragmented across different vial materials, stopper designs, test methods, temperatures and exposure conditions. A helium-leak test can answer a different question from headspace analysis. A thermal-cycling experiment can reveal a different failure mode from long-term storage.

This distinction is increasingly important as therapies become harder to test. Cryogenic products can be fragile, expensive or available only in very small quantities, making conventional testing strategies difficult to apply..

1. Biffa internal savings data, average saving (January - August 2023)
2. Nisbets internal savings data, average saving (January – September 2023)
3. Compliance365 internal data, average  savings
4. HEINEKEN UK data, Calculations based on SmartDispense® active accounts each year since 2015 with 10 lines
5. Independent test results based on subterranean and ground floor pub cellars of varying sizes
6. Independent test results based on subterranean and ground floor pub cellars of varying sizes

A 2026 Journal of Pharmaceutical Sciences perspective by a cross-industry group places CCI within precisely this broader problem. The authors classify ultra-low-temperature products below –70°C and cryogenic products below –150°C among difficult-to-test parenteral products and propose a tailored, lifecycle-based strategy.

Their recommendation is not a new regulatory requirement. The authors explicitly describe the approach as a starting point for further discussion, particularly with regulators. It is instead a recognition that CCI assurance has to extend across development, manufacturing, stability and transportation, with surrogate-filled or empty container-closure systems potentially allowing sensitive testing when drug product is scarce or hazardous.

For manufacturers, that changes the strategic question. The task is no longer simply to identify a vial that survives extreme cold. It is to construct a chain of evidence showing that the complete container-closure system remains fit for purpose throughout the product’s actual lifecycle. .At that point, packaging ceases to be an invisible component of the medicinal product and becomes part of the proof that the product remained protected. The question facing manufacturers is no longer whether a container can survive the cold, but whether they can demonstrate, with evidence matched to the failure modes that matter, that it maintained integrity throughout.

1. Biffa internal savings data, average saving (January - August 2023)
2. Nisbets internal savings data, average saving (January – September 2023)
3. Compliance365 internal data, average  savings
4. HEINEKEN UK data, Calculations based on SmartDispense® active accounts each year since 2015 with 10 lines
5. Independent test results based on subterranean and ground floor pub cellars of varying sizes
6. Independent test results based on subterranean and ground floor pub cellars of varying sizes