Pharmaceutical packaging does more than contain a product. It directly influences product protection, shelf life, and contamination risk.

Packaging materials are designed to preserve formulation quality, support stability, and protect the product throughout storage and use. But they can also introduce chemical risk.

Materials used in containers, closures, liners, tubing, seals, and other packaging-associated components may release compounds into the drug product under certain conditions. These compounds are known as extractables and leachables.

Even at low levels, they can affect product quality, stability, patient safety, and regulatory acceptability.

That is why understanding the common sources of extractables and leachables in pharmaceutical packaging systems is so important.

For pharmaceutical teams, E&L risk is not limited to the obvious primary container. It can arise from multiple packaging-related risk points across the full product-contact system.

A clear understanding of where these compounds come from supports better material selection, stronger risk assessment, and more reliable E&L testing strategies.

What Are the Common Sources of Extractables and Leachables in Pharmaceutical Packaging Systems?

Common sources of extractables and leachables in pharmaceutical packaging systems include plastic containers, rubber closures, elastomeric seals, liners, tubing, gaskets, adhesives, inks, coatings, and other polymer-based or chemically treated packaging materials.

These materials may contain additives, residual monomers, processing agents, degradation products, or other chemical constituents that can migrate into the drug product under certain conditions.

Understanding these sources is essential for controlling contamination risk, supporting product safety, and ensuring regulatory compliance.

What Extractables and Leachables Mean in Packaging Systems

Extractables are chemical compounds that can be released from packaging materials under aggressive laboratory conditions.

Leachables are compounds that actually migrate into the drug product under normal storage or use conditions.

The two are closely related.

Extractables studies help identify what a packaging material could release. Leachables studies help determine what the actual product may be exposed to over time.

Leachable risk depends on the interaction between packaging composition, formulation chemistry, contact conditions, and time-dependent migration behaviour.

In pharmaceutical packaging systems, both are important because they help teams understand contamination risk before it becomes a quality or safety issue.

Why Packaging Materials Can Become a Source of Chemical Risk

Packaging materials are rarely chemically simple.

They are often made using polymers, elastomers, additives, stabilisers, colourants, lubricants, curing agents, and processing aids.

Even if a packaging component is functionally suitable, its chemical composition may still create E&L risk.

This can happen because of:

• direct contact with the drug product,
• long-term storage,
• temperature exposure,
• solvent interaction,
• moisture exposure,
• sterilisation conditions,
• mechanical stress,
• or degradation over time.

The more complex the packaging configuration, the more important it becomes to understand where E&L risk may originate.

Primary Containers as a Major Source of Extractables and Leachables

The primary container is one of the most important places to assess.

This is the component that directly holds the drug product. Because it remains in direct contact for extended periods, it is often a major source of E&L risk.

Common primary container materials include:

• plastic bottles,
• prefilled syringes,
• plastic ampoules,
• polymer-based vials,
• blow-fill-seal containers,
• and other plastic or composite systems.

Potential risk can come from the base polymer itself, but also from additives used during manufacturing.

These may include antioxidants, plasticisers, stabilisers, slip agents, residual monomers, oligomers, or degradation products.

In many cases, the container material is not the only concern. Its interaction with the formulation also matters.

A solvent-rich, lipid-based, or otherwise reactive product may increase the likelihood of chemical migration.

Closures and Stoppers as Common E&L Sources

Rubber closures, elastomeric stoppers, septa, and caps are also common material-origin contamination sources.

These components are widely used in injectable products, vials, and other pharmaceutical packaging systems.

They often contain complex formulations made from elastomeric materials along with curing agents, fillers, lubricants, pigments, and stabilisers.

Because they are designed for sealing, puncture resistance, flexibility, and compatibility with sterilisation, they may contain multiple chemical constituents that need careful evaluation.

Potential E&L sources from closures and stoppers include:

• vulcanisation-related compounds,
• antioxidants,
• residual processing chemicals,
• oligomeric substances,
• and degradation by-products.

Even when the closure has limited direct surface area compared with the container, it can still be a meaningful contributor to leachables risk, especially in long-term storage systems.

Liners, Seals, and Gaskets in Packaging Systems

Liners, inner seals, induction seals, and gaskets are often overlooked during packaging risk assessment.

However, these components can become important E&L sources because they may sit close to or directly contact the product or the headspace environment.

These parts are frequently made from layered or composite materials.

They may include polymer films, adhesives, foil structures, elastomeric materials, or protective coatings.

Each additional material layer creates new potential sources of extractable compounds.

If the packaging system includes:

• bottle cap liners,
• sealing membranes,
• gasket materials,
• or inner barrier layers,

they should be considered carefully during E&L evaluation.

Tubing and Fluid Path Components as Hidden Sources

In some pharmaceutical products, especially those involving sterile filling, delivery devices, or combination products, tubing and fluid path materials become critical.

These materials may not always remain part of the final visible package, but they can still contribute extractable or leachable compounds during manufacturing, storage, or administration.

Common fluid path components include:

• transfer tubing,
• filling lines,
• pump components,
• connectors,
• valve materials,
• and flexible polymer pathways.

These materials may contain plasticisers, stabilisers, processing aids, and polymer-related residuals.

If they contact the product or formulation stream, they should be considered part of the total E&L risk picture.

Adhesives, Inks, and Coatings as Secondary but Important Sources

Adhesives, label inks, printing materials, and protective coatings may not always contact the drug product directly.

However, they should not be ignored.

In some packaging systems, these materials may contribute volatile, semi-volatile, or migratory compounds through diffusion, vapour transfer, or indirect contact pathways.

Possible sources include:

• label adhesives,
• printed markings,
• coating systems,
• laminated structures,
• heat-seal coatings,
• and decorative or functional surface treatments.

These are especially relevant when packaging systems involve multilayer structures, high-temperature exposure, or products sensitive to trace contamination.

Polymer Additives as a Major Chemical Origin of E&L Risk

A major source of E&L risk often comes not from the bulk packaging polymer alone, but from the additives blended into it.

Packaging materials may contain substances added to improve:

• flexibility,
• durability,
• heat resistance,
• processability,
• clarity,
• colour,
• or shelf-life stability.

These additives may include:

• antioxidants,
• plasticisers,
• slip agents,
• antistatic agents,
• UV stabilisers,
• lubricants,
• and curing residues.

Over time, these compounds or their degradation products may migrate out of the packaging material and become part of the extractables or leachables profile.

This is why understanding full material composition matters so much in packaging qualification.

Residual Monomers, Oligomers, and Processing Agents

Another important source of extractables and leachables comes from materials left behind after manufacturing.

These may include:

• residual monomers,
• short-chain oligomers,
• catalysts,
• solvents,
• and other processing-related substances.

Even when present in small amounts, such compounds can become relevant depending on the product type, route of administration, storage time, and formulation sensitivity.

This is particularly important in polymer-based packaging systems where incomplete reaction, curing, or purification may leave trace chemical residues behind.

Degradation Products Formed During Shelf Life

Not all E&L sources are present only at the start.

Some compounds may form later as the packaging material ages or degrades.

Exposure to heat, light, oxygen, sterilisation, mechanical stress, or long-term storage can change the chemistry of packaging materials over time.

This may lead to the formation of new degradation products that were not significant in the original material state.

That is why E&L risk assessment should consider not only material composition, but also material behaviour throughout the full product lifecycle.

Product Categories With Higher E&L Sensitivity

E&L concerns are especially significant in products where patient exposure risk, formulation sensitivity, or packaging interaction potential is higher.

This often includes:

• injectables,
• inhalation products,
• ophthalmic products,
• biologics,
• solvent-rich formulations,
• lipid-based products,
• and long-term storage systems.

In these categories, even low-level migratory compounds may be more important from both safety and regulatory perspectives.

This makes packaging material review and E&L testing particularly critical.

Why Drug Product Type Influences E&L Risk

The source of extractables and leachables is not determined only by the packaging material.

The drug product itself also influences risk.

Different formulations interact with packaging materials in different ways.

Factors that may increase migration risk include:

• high solvent content,
• lipid-rich systems,
• extreme pH,
• surfactants,
• long contact time,
• elevated storage temperature,
• and sensitive routes of administration.

A packaging component that performs well for one product may present more E&L concern for another.

This is why packaging risk must always be evaluated in the context of the actual formulation.

Common Packaging Components That Should Be Reviewed During E&L Assessment

When planning an E&L study, pharmaceutical teams should review all relevant packaging-associated components, including:

• primary containers,
• caps and closures,
• rubber stoppers,
• septa,
• liners,
• seals,
• gaskets,
• tubing,
• connectors,
• fluid path components,
• adhesives,
• coatings,
• inks,
• and multilayer barrier materials.

A narrow view of packaging risk may miss meaningful contamination sources.

A system-level review is often the better approach.

How E&L Testing Helps Control Packaging-Related Risk

Extractables and leachables testing helps teams understand which packaging materials may release compounds, under what conditions, and whether those compounds create meaningful product risk.

This supports:

• better material selection,
• packaging qualification,
• contamination control,
• safety assessment,
• regulatory readiness,
• and long-term lifecycle management.

Without proper E&L testing, packaging-related contamination may remain unnoticed until later in development, stability studies, or regulatory review.

A stronger E&L strategy helps reduce that risk.

Regulatory Importance of Understanding E&L Sources

Understanding where extractables and leachables come from is not only a scientific concern.

It is also a regulatory one.

Pharmaceutical companies are expected to show that packaging systems are suitable for their intended use and do not introduce unacceptable contamination risk.

That means teams need clear knowledge of:

• which components may contribute extractables,
• which compounds may become leachables,
• how the formulation interacts with packaging,
• and how the overall packaging system is justified.

A strong understanding of common E&L sources supports better risk assessment, study design, documentation, and regulatory confidence.

Best Practices for Identifying E&L Sources Early

To improve packaging risk control, teams should follow a structured approach.

Review the Full Packaging System

Do not focus only on the main container.

Assess all product-contact and packaging-associated materials.

Understand Material Composition

Know the likely additives, elastomer components, coatings, and process-related residues within the materials used.

Consider the Formulation Context

Evaluate how the actual drug product may interact with the packaging system.

Include Secondary Risk Sources

Do not ignore adhesives, inks, coatings, and fluid path materials if they may contribute indirectly.

Use E&L Testing as a Development Tool

Early extractables and leachables work can prevent later surprises during stability studies or regulatory review.

At topiox research, this kind of structured assessment helps pharmaceutical teams understand where packaging-related contamination risk begins and how to control it scientifically.

Conclusion

Extractables and leachables risk in pharmaceutical packaging systems can arise from many different sources, not just the main container.

Plastic materials, elastomeric closures, liners, seals, tubing, adhesives, coatings, additives, residual monomers, and degradation products can all contribute to the overall contamination profile.

That is why understanding the common sources of extractables and leachables is a critical step in protecting product quality, patient safety, and regulatory acceptability.

A strong packaging strategy requires more than mechanical suitability. It requires understanding how packaging materials behave chemically over time and in contact with the actual drug product.

At topiox research, extractables and leachables testing is approached as a scientific tool for identifying packaging-related risk early, supporting material qualification, and strengthening pharmaceutical product safety.

Need support with extractables and leachables testing, packaging risk assessment, or material qualification for pharmaceutical products? Connect with topiox research for scientifically structured E&L solutions tailored to complex packaging systems.