Extractable and Leachable Challenges in Lyophilized Drug Products

Macro view on vials | Image Credit: © yuriygolub - stock.adobe.com

Lyophilization is a sophisticated preservation technique designed to stabilize sensitive pharmaceutical compounds by removing water through a meticulously controlled process of freezing and sublimation under vacuum conditions. This method is indispensable for the stability and long-term efficacy of medications that otherwise would have excessively stringent requirements for temperature and humidity control. Despite its advantages, the lyophilization process introduces a complex interplay between the drug product and its packaging materials. Exploring the challenges inherent in testing and mitigating extractables and leachables (E&L) risks require innovative solutions grounded in regulatory guidance as well as advancements in analytical methods, primary packaging and systemic collaborations.

Key benefits and associated challenges of lyophilization

Lyophilization involves transforming liquid formulations into stable, lightweight, and portable solid forms known as lyo cakes. The process consists of three primary stages: freezing, primary drying (sublimation), and secondary drying (desorption). This transformative process not only ensures the preservation of the drug's chemical and physical integrity but also allows simpler storage and transportation such at room temperature. However, the absence of water and the unique characteristics of the resulting solid-state product amplify certain E&L contamination risks due to interaction with packaging materials.

Primary packaging materials, including glass vials and rubber stoppers, are integral to maintaining the stability of lyophilized drug products. However, these materials can release volatile and semi-volatile compounds through mechanisms such as outgassing, which accumulate on the highly absorbent surfaces of the lyo cake. Secondary packaging systems, such as multilayer films and aluminum pouches, though designed to shield against external contaminants, may also contribute to E&L risks under varying environmental conditions such as temperature and humidity fluctuations. These interactions necessitate rigorous testing and validation protocols to mitigate potential contamination and ensure the drug product's long-term stability.

Understanding the fundamentals

Extractables are chemical entities that can be released from packaging materials under controlled but often extreme conditions, such as exposure to solvents, elevated temperatures, or pressure.Leachables are substances that migrate into the drug product under standard storage or usage conditions, potentially compromising its safety, efficacy, and stability.

In lyophilized drug products, E&L interactions predominantly occur through outgassing, where volatile and semi-volatile organic compounds from packaging materials, particularly rubber stoppers, migrate into the vial's headspace and adsorb onto the dry lyo cake. The high surface area and extreme dryness of the lyo cake exacerbate this absorption. Additionally, reactive leachables may interact with APIs or excipients, creating byproducts that can compromise drug quality and pose safety risks to patients.

Regulatory frameworks for E&L evaluation

Both the United States Food and Drug Administration (FDA) and United States Pharmacopeia (USP) <1664> categorize product interaction risk (1) or specifically leachables risk (2) based on the dosage form and administration route. For lyophilized drugs (powders for injection/reconstitution), while the leachables risk of direct interaction during solid-state storage is considered low, the reconstitution phase significantly elevates these risks. Furthermore, worst-case scenario testing can be utilized to ensure leachables remain within acceptable safety limits under real-world conditions.

The European Medicines Agency (EMA)'s guidelines includes a decision-tree approach for assessing packaging interactions (3). For drugs intended for parenteral administration, the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use considerations (ICH) also recommends long-term stability studies and accelerated testing to identify cumulative leachables over the product’s lifecycle (4). Real-world simulations, including variations in temperature and humidity, are emphasized to ensure comprehensive compliance.

Challenges in E&L testing for lyophilized products

The following are some challenges in E&L testing for lyophilized products.

Outgassing and progressive accumulation

Rubber stoppers release volatile and semi-volatile organic compounds, which continuously accumulate on the lyo cake during storage. This progressive outgassing, coupled with the lack of equilibrium in the vial's headspace, leads to increasing contamination levels over time.

Reconstitution-induced risks

Reconstitution introduces additional complexities as volatile and semi-volatile compounds solubilize in the diluent. This step also allows short-term interactions between the liquid drug product and the primary packaging, potentially introducing new contaminants, including metals and ions. Such multifaceted interactions demand extensive testing to ensure product safety.

Analytical complexities and the absence of true blank solutions

A major limitation in E&L testing for lyophilized products is the challenge of establishing a true blank solution. Because the lyophilization process inherently involves packaging contact, alternative approaches, such as time-point zero baselines, must be employed. However, these methods are imperfect and introduce uncertainties in distinguishing between inherent impurities and leachables. Advanced analytical techniques, including high-sensitivity liquid chromatography–mass spectrometry (LC–MS) and gas chromatography–MS (GC–MS), are indispensable but require significant expertise and resources to implement effectively.

Strategies for mitigating E&L risks

The choice of packaging materials plays a pivotal role in minimizing E&L risks. Utilizing low-alkali glass and high-quality, low-residual rubber stoppers can significantly reduce contamination. Proactive collaboration with suppliers during material selection and validation helps demonstrate compatibility with the lyophilized drug product.

E&L studies must encompass both extractables and leachables testing under simulated real-world and worst-case scenarios. This includes rigorous assessments during storage, reconstitution, and administration. Predictive modeling tools and accelerated testing techniques can enhance study efficiency and provide robust data.

Innovative packaging designs, such as non-contact systems and reduced headspace configurations, minimize the accumulation of leachables. Coated or laminated materials further reduce the migration of harmful compounds, ensuring better product safety.

Developing standardized methodologies across the pharmaceutical industry ensures consistency, improves compliance, and facilitates data sharing. Such protocols should address the entire lifecycle of lyophilized products, from manufacturing to patient administration.

Post-market surveillance programs and ongoing reviews of packaging materials and processes are essential for adapting to emerging risks and regulatory changes. Pharmaceutical companies can leverage feedback from real-world usage to help collaborate with container manufacturers and analytical laboratories to identify and address vulnerabilities proactively.

Conclusion

The unique characteristics of lyophilized drug products amplify their unique E&L risks. These challenges arise from complex interactions between the drug product and its packaging during storage, reconstitution, and administration. Addressing these risks requires a multidisciplinary approach involving advanced material science, rigorous testing methodologies, and compliance with global regulatory standards. By adopting innovative packaging technologies, implementing comprehensive E&L studies, and fostering continuous improvement, the pharmaceutical industry can ensure the safety, efficacy, and quality of lyophilized medications. As advancements in analytical tools and packaging materials continue, continuous investment in E&L practices will further enhance the reliability of life-saving therapeutics, safeguard patient health and maintain global trust in pharmaceutical innovations.

References

1. FDA, Guidance for Industry, Container Closure Systems for Packaging Human Drugs and Biologics (CDER/CBER, July 1999).
2. USP, USP General Chapter <1664>, “Assessment of Drug Product Leachables Associated with Pharmaceutical Packaging/Delivery Systems,” USP 41-NF 36, 1850 (Rockville, MD, 2016).
3. EMA, CPMP/QWP/4359/03, Plastic Primary Packaging Materials – Scientific Guideline (May 19, 2005).
4. ICH, Q8 (R2) Pharmaceutical Development – Scientific Guideline, Step 5 version (2006).

About the authors

Alan Xu is product manager, analytical services at Stevanato Group, and Piet Christiaens is scientific director at Nelson Labs Europe.

Article details

BioPharm International®
Vol. 38, No. 2
March 2025
Pages: 29–30

Citation

When referring to this article, please cite it as Xu, A. and Christiaens, P. Extractable and Leachable Challenges in Lyophilized Drug Products. BioPharm International 2025 38 (2).