How to prevent temperature excursions in pharmaceutical cold chain

In biologics logistics, there are established temperature ranges for refrigerating and freezing drug substances and products. Logistics partners need to handle products across these ranges with flexible capabilities underpinned by robust standard operating procedures (SOPs). Controls for temperature and humidity during storage and transportation must be carefully considered and monitored in real time, with risk management systems and continuity plans in place in case of control failures. Tracking and monitoring technology is vital to ensure high fidelity of temperature data in transit, informing decision-making at every stage of the supply chain.

This article will explain what temperature excursions are, why they matter, common causes for temperature excursions in pharmaceutical cold chain, and how to prevent them.

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What is a temperature excursion?

A temperature excursion is any instance where a pharmaceutical product is exposed to conditions outside its defined acceptable temperature range. This can be too hot or too cold, and whether for a brief moment or an extended period.

These events can degrade products such as insulin and vaccines, leading to lost potency and the formation of harmful impurities, as well as significant economic waste. Because pharmaceutical products are often manufactured in limited quantities and carry high per-unit value, even a single excursion event can have serious downstream consequences for both the supply chain and the patients depending on those products.

Why do temperature excursions in the pharmaceutical cold chain matter?

Temperature excursions in the pharmaceutical cold chain are not merely a logistics inconvenience. Rather, they represent a direct threat to product integrity, regulatory compliance, and patient safety. The World Health Organization (WHO) estimates that up to a quarter of vaccines arrive at their destination in a degraded state due to cold chain failures, a figure that underscores the systemic scale of the problem.¹ Understanding the specific mechanisms of damage helps to illustrate why prevention is so critical.

Protein denaturation

Many modern pharmaceutical products — in particular biologics — rely on precisely folded protein structures to deliver their therapeutic effect. When exposed to temperatures outside approved ranges, proteins can unfold or aggregate. This process is known as denaturation. Once denatured, a biologic cannot be restored to its original structure and its therapeutic efficacy is permanently compromised. For cell and gene therapies (CGTs), which are often patient-specific and manufactured in small quantities, this kind of damage can be especially consequential.

 

Chemical degradation

Temperature excursions accelerate the rate of molecular breakdown within pharmaceutical compounds. Higher than normal temperatures can trigger chemical reactions that produce toxic byproducts or cause the active ingredient to become inactive. Unlike biological degradation, chemical degradation can occur without any visible change to the product — making it particularly difficult to detect without testing.

Invisible damage

Perhaps the most insidious consequence of temperature excursions is that the damage is often invisible. A vaccine vial that has been exposed to an excursion event may appear completely normal: clear, properly sealed, and correctly labelled. Yet chemically, it may have lost efficacy or become harmful. This is why inspection by eye alone is never sufficient, and why comprehensive monitoring and stability data are essential to any responsible cold chain program.

Common factors which lead to temperature excursions in the pharmaceutical cold chain

Understanding where and why temperature excursions occur is the first step to preventing them. The International Air Transport Association (IATA) has identified airport handling — particularly tarmac exposure during transfers — as one of the highest risk points in the global pharmaceutical cold chain, with temperature-sensitive products frequently exposed to ambient conditions that fall well outside their labelled storage requirements.²

Logistical delays

One of the most common causes of temperature excursions is delays during handoffs — particularly between freight carriers and warehouse facilities. There, shipments can sit on un-airconditioned tarmacs for extended periods. Even a relatively brief delay in extreme ambient conditions can be enough to push a temperature-sensitive product outside its acceptable range. Tight shipping windows, which are common with patient-specific CGTs, make these delays especially high-risk.

Equipment failure

Malfunctioning refrigeration units, cold rooms, and faulty cooling blankets are a leading cause of temperature excursions across the cold chain. A reefer unit (short for ‘refrigerated unit’) that stops cycling correctly may not trigger an alarm immediately. This allows a temperature breach to develop undetected over several hours. Without real-time monitoring, these failures are often only identified after the fact, when product damage has already occurred.

Inadequate packaging

Using the wrong type of gel packs or insufficient insulation — particularly during periods of extreme ambient temperature — can allow heat transfer that overwhelms a package's thermal protection. Packaging decisions that are not validated against worst-case climate conditions leave products vulnerable, especially on longer routes or during seasonal temperature peaks.

The regulatory temperature ranges and Mean Kinetic Temperature (MKT) for temperature excursions

Pharmaceutical products are classified by their required storage conditions, and any deviation from these ranges constitutes a temperature excursion that must be documented and assessed. The main classifications are:

Temperature range name	Temperature range	Applicable products
Cryogenic	as low as -150°C or colder	patient cells or manufactured personalized cell therapies
Cold or refrigerated	+2°C to +8°C	products such as vaccines and insulin
Frozen	-25°C to -10°C
Ultra-cold/Deep Frozen	-80°C to -60°C	mRNA vaccines and certain advanced therapies
Controlled room temperature (CRT)	+20°C to +25°C	many oral solid dosage forms

Alongside these storage classifications, the concept of Mean Kinetic Temperature (MKT) plays an important role in excursion assessment. Governed by USP General Chapter <1079> and the more detailed USP <1079.2>, MKT is a weighted, non-linear average — derived from the Arrhenius equation — that calculates the total thermal exposure a product has experienced over a specific duration.³ It provides that a brief temperature spike may be acceptable if the overall thermal burden remains within approved stability limits, preventing unnecessary product rejection. The ICH Q1A(R2) guideline on stability testing further supports MKT as the standard framework for evaluating the cumulative impact of temperature variations on product quality.⁴

Global specialty drug distribution industry market growth

The specialty drug distribution market continues to expand rapidly, driven in large part by the growth of biologics and advanced therapies that require cold chain infrastructure. The global specialty drugs market was valued at approximately USD 475 billion in 2025 and is projected to reach USD 883 billion by 2034, growing at a CAGR of over 7% — with biologics as the fastest-growing segment at a CAGR of 13.68%.⁵

This growth is partly driven by the rise in the development and manufacturing of new vaccines and CGTs. CGTs are promising therapeutics for treating chronic diseases, but often require cryogenic storage for long-term stability.

Patient-specific CGTs add further complexity due to the need for temperature-controlled transport at multiple points: collecting patient cells, manufacturing the therapy, and administering it to the patient. This results in tight shipping windows, demanding cold storage infrastructure, thermally-controlled packaging technology, and strict regulatory requirements that must satisfy both manufacturer and patient needs.
To help overcome these challenges, pharmaceutical companies increasingly logistics providers that are highly specialized in life sciences and pharmaceuticals. Following robust SOPs, these medical couriers provide solutions for pharmaceutical cold chain logistics that ensure efficient, temperature-controlled delivery of drug substances and products.

How to prevent temperature excursions in the pharmaceutical cold chain

Devise a strategy for temperature excursions early

It is important to plan and implement a cold chain supply strategy early in product development to ensure it can be relied on and can be scaled up. Though a product may not make it to market, this proactive approach identifies and mitigates problems so that the therapy reaches its destination swiftly once approved. It also aids in eliminating the risk of an excursion event when a time- and temperature-sensitive pharmaceutical product (TTSPP) is outside a set range or time. However, unforeseen circumstances can still lead to temperature excursions in the pharmaceutical cold chain and during shipment. For this reason, real-time visibility and multiple contingency protocols must accompany any early strategy.

Use real-time monitoring

Tracking and monitoring technology is central to preventing and responding to temperature excursions. Real-time monitoring provides unbroken visibility into a product's temperature conditions throughout its journey. This then enables logistics teams to issue proactive alerts and intervene before an excursion escalates. This is a significant advantage over passive data loggers, which only document excursions after delivery, when product damage has already occurred and intervention is no longer possible.

The tracking data collected carries great value in informing decisions at every stage of a company's critical time- and temperature-sensitive supply chain. IoT-enabled devices with cellular or satellite connectivity — logging data every five to 15 minutes at an accuracy of ±0.5°C or better — now make continuous real-time monitoring both practical and cost-effective.

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Implement corrective measures for temperature excursions

If a temperature excursion event is recorded, corrective measures can be taken to re-establish appropriate conditions. However, there is always a patient at the end of the supply chain, and lives can be at stake. Therefore, any recorded discrepancy must be investigated before a drug is administered, even if product conditions appear to have been quickly re-established.

Where a temperature excursion has been identified, a decision tree informed by stability testing data, collected tracking records, and the optimized distribution strategy can be used to determine whether to release a drug batch. The drug will either be deemed safe for administration or rendered unusable.

Temperature excursion decision tree example:

 

Conduct analysis and enable continuous improvement

In addition to real-time monitoring, all collected data can be analyzed to identify recurring problems and areas for improvement. If one route consistently leads to delays — and therefore higher excursion risk — an alternative can be selected. If a particular packaging configuration correlates with a statistically higher rate of excursions, alternative packaging can be sourced and validated. This continuous improvement process helps build a more robust strategy over time and further mitigates the risks associated with cold chain supply.

Conclusion

Temperature excursions can occur anywhere within the production and distribution timeline. As manufacturers must adhere to good manufacturing practice (GMP) and good distribution practice (GDP) guidelines, recording any temperature variations throughout this timeline is critical. Having a logistics partner with robust temperature-controlled handling and transportation capabilities — and a clear, product-tailored strategy — is essential for efficient and safe distribution, and ultimately for ensuring business continuity.

Coupled with accurate technology to monitor temperature excursions, a safe and efficacious product can be delivered to its destination, ready for patient administration and helping to create healthier futures.

Sources

¹ World Health Organization. Immunization Supply Chain and Logistics: A Neglected but Essential System for National Immunization Programmes. WHO, 2015. Available at: who.int

² International Air Transport Association (IATA). Perishable Cargo Regulations (PCR). IATA, 2020. Available at: iata.org

³ United States Pharmacopeia. General Chapter <1079> Good Storage and Distribution Practices for Drug Products and General Chapter <1079.2> Mean Kinetic Temperature in the Evaluation of Temperature Excursions During Storage of Drug Products. USP, updated 2025. Available at: usp.org

⁴ International Council for Harmonisation. ICH Q1A(R2): Stability Testing of New Drug Substances and Products. ICH, 2003 (current revision). Available at: ich.org

⁵ Fortune Business Insights. Specialty Drugs Market Size, Share & Industry Analysis, 2026–2034. Fortune Business Insights, June 2026. Available at: fortunebusinessinsights.com