What Are Extractables and Leachables?

Extractables are compounds that can be forced out of container materials using aggressive solvents under exaggerated conditions. They represent the worst-case potential for contamination.

Leachables are compounds that actually migrate into the drug product under real storage or usage conditions. They reflect the true patient exposure risk.

Both must be evaluated during container qualification and stability testing, especially for products with long shelf lives, high sensitivities, or delivered via parenteral or inhalation routes.

Why E&L Testing Is Required

• To prevent chemical contamination of the drug product
• To support toxicological safety and patient protection
• To meet global regulatory requirements (e.g., USP , , ICH Q3D)
• To qualify packaging components as part of CTD Module 3 submissions
• To comply with GMP risk-based design and lifecycle approach

Failure to provide E&L data has resulted in delayed approvals and regulatory warning letters.

Step-by-Step Guide to E&L Testing

Step 1: Risk Assessment and Material Selection

Begin with a comprehensive risk assessment based on:

• Drug dosage form (e.g., injectable, inhaled, ophthalmic = high risk)
• Contact time and conditions (e.g., long-term liquid contact)
• Packaging material composition (e.g., elastomers, plastics, adhesives)
• Patient population (e.g., pediatrics, geriatrics = more sensitive)

Materials with high extractables potential (e.g., PVC, rubber) require more stringent evaluation.

Step 2: Design of Extractables Study

• Use exaggerated conditions: high temperature, strong solvents, prolonged contact
• Solvents commonly used: water, 50% ethanol, isopropanol, acid/base buffers
• Time points: 24 hours to 1 week, depending on material and solvent
• Analytical methods: GC-MS, LC-MS, FTIR, ICP-MS, UV, TOC
• Ensure method validation for specificity, sensitivity, and reproducibility

Results form the “Extractables Profile” for the component under test.

Step 3: Design of Leachables Study

Leachables studies must reflect actual conditions of drug product storage:

• Use final drug product formulation
• Use market packaging configuration (e.g., vial + stopper + seal)
• Store under ICH conditions (e.g., 25°C/60% RH, 40°C/75% RH)
• Typical time points: 1, 3, 6, 12 months
• Screen for targeted and untargeted leachables using validated methods

Compare leachables to extractables profile to understand potential migration patterns.

Step 4: Toxicological Assessment of Leachables

Every leachable compound detected must undergo a toxicological evaluation. Key considerations include:

• Structural identification: Match each peak to known chemical entities
• Safety thresholds: Compare detected levels with PDEs (Permitted Daily Exposures) per ICH Q3D
• Genotoxicity screening: For unknown or borderline compounds
• Risk characterization: Based on route of administration, patient population, and cumulative exposure

Summarize all results in a toxicological risk assessment report, ideally prepared by a qualified toxicologist.

Reporting E&L Findings in Regulatory Submissions

Results must be included in CTD Module 3, specifically:

• 3.2.P.2.4: Discussion of packaging development and rationale
• 3.2.P.7: Specifications of container closure components and E&L data
• 3.2.P.8: Stability data showing leachables over time

Attach study protocols, raw data, chromatograms, validation reports, and toxicological summaries in Module 3.3 (Regional Information).

Regulatory Guidelines Referencing E&L

Global regulatory expectations for extractables and leachables include:

• USP : Assessment of Extractables Associated with Pharmaceutical Packaging
• USP : Assessment of Drug Product Leachables
• FDA Guidance: Container Closure Systems for Packaging Human Drugs
• ICH Q3D: Guideline for Elemental Impurities
• EMA and WHO guidelines on packaging materials

Refer to regulatory compliance resources to align your studies with these expectations.

Common Mistakes in E&L Studies and How to Avoid Them

• Not conducting extractables study prior to leachables – this limits comparison
• Using placebo or water instead of real product – doesn’t reflect actual risk
• Limited timepoints – at least 3 points across the shelf life should be tested
• No toxicological justification – regulators expect risk assessments
• Using non-validated or overly sensitive analytical methods – leads to false positives

Ensure thorough planning and consultation with analytical, formulation, and toxicology teams before beginning E&L programs.

Case Study: Injectable Product E&L Deficiency

A USFDA inspection of a parenteral manufacturer revealed missing leachables data for bromobutyl stoppers used in lyophilized vials. Although extractables were provided, the company failed to submit time-based leachables data under accelerated conditions. The FDA issued a 483 observation, and product approval was delayed until complete leachables testing was conducted. The cost of re-initiating the study delayed commercialization by 9 months.

Best Practices for Successful E&L Programs

• Involve toxicologists early to define analytical thresholds
• Choose analytical methods based on expected compound types
• Conduct both targeted and untargeted screening
• Ensure extractables studies reflect container contact materials
• Incorporate leachables study into your validation protocol

These steps ensure better predictability of interactions and streamline regulatory approval.

Conclusion

Extractables and leachables testing is not just a regulatory checkbox—it is a scientific necessity to ensure packaging safety, product stability, and patient protection. By designing a robust E&L strategy grounded in risk-based principles, and presenting the findings clearly in the CTD, pharmaceutical companies can demonstrate the suitability of their container closure systems. This fosters compliance, minimizes regulatory delays, and ultimately ensures patient safety across product lifecycles.

References:

• USP and Monographs
• ICH Q3D Guideline for Elemental Impurities
• FDA Guidance for Industry – Container Closure Systems
• WHO Technical Report Series on Packaging
• EMA Quality Guidelines on Pharmaceutical Packaging

Why Material Compatibility Matters in Stability Testing

Pharmaceutical products, especially those with sensitive APIs or excipients, may react with packaging components. These reactions can lead to physical instability, chemical degradation, or contamination. Therefore, understanding the interaction between the drug product and packaging materials is critical when designing a container closure system (CCS) for stability studies.

Regulatory bodies like CDSCO and ICH require thorough material compatibility evaluations prior to stability initiation.

Common Packaging Materials and Their Risk Profiles

• Type I Glass: High chemical resistance, ideal for injectables and biologicals.
• Type II/III Glass: Used for oral liquids, moderate resistance, may interact with alkaline solutions.
• Plastic (HDPE, PET, PVC): Cost-effective but prone to leaching, oxygen permeation, or sorption.
• Rubber Closures: Require coating or treatment to reduce extractables and leachables.
• Aluminum Foils: Used in blister packaging; effectiveness depends on laminate layers.

The choice of material must align with the product’s physicochemical profile and dosage form.

Types of Drug-Packaging Interactions

Here are the key types of interactions to watch for:

1. Adsorption: API or excipients adhere to the container wall, reducing potency.
2. Absorption: Packaging materials absorb solvents, water, or actives.
3. Leaching: Additives from the container (e.g., plasticizers, stabilizers) migrate into the product.
4. Permeation: External gases like oxygen or moisture penetrate the packaging, degrading the product.
5. Chemical Reaction: Incompatibility leading to discoloration, precipitate, or degradation.

Long-Term Impacts of Poor Material Compatibility

Consequences of overlooking compatibility include:

• Loss of potency or therapeutic activity
• Formation of harmful degradation products
• Adverse patient reactions due to leachables
• Regulatory non-compliance and stability failures

Hence, conducting a thorough compatibility risk assessment early in development is non-negotiable.

Step-by-Step Guide to Conduct Material Compatibility Studies

1. Shortlist primary container and closure candidates.
2. Prepare sample batches of drug product in each candidate material.
3. Store under ICH recommended conditions (25°C/60% RH, 40°C/75% RH, etc.).
4. Analyze for:
   • Assay and degradation products
   • pH, clarity, color, and odor
   • Particulate matter
   • Extractables and leachables
5. Compare with control stored in inert glass.

Use analytical tools like HPLC, GC-MS, ICP-MS, and UV spectrophotometry for detection.

Examples of Common Compatibility Challenges

• Low-dose APIs in prefilled syringes: Prone to adsorption on plastic surfaces.
• Proteins in plastic containers: May denature due to hydrophobic interactions.
• Sorbents in closures: Cause unintentional water loss, altering formulation balance.

These issues are often caught during compatibility simulation studies prior to stability trials.

Relevant SOPs and Guidelines to Reference

• SOP writing in pharma
• Regulatory compliance

USP and ICH Guidelines on Material Compatibility

Two key guidances govern material compatibility evaluation:

• USP : Assessment of extractables associated with pharmaceutical packaging.
• ICH Q3D: Elemental impurities guideline—important for metal leaching.

Use these documents to design your extractables and leachables (E&L) study protocols. Regulatory agencies will expect this data during dossier submission and GMP inspections.

How to Analyze Extractables and Leachables

Extractables are chemical compounds that can be released under aggressive conditions, while leachables are those that migrate under actual storage conditions. The analysis must include:

1. Polymer breakdown products (e.g., phthalates, aldehydes)
2. Metals (e.g., arsenic, cadmium, lead)
3. Volatile Organic Compounds (VOCs)
4. Siloxanes, stabilizers, UV blockers

Use orthogonal methods such as:

• Gas Chromatography-Mass Spectrometry (GC-MS)
• Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)
• Liquid Chromatography-Mass Spectrometry (LC-MS)
• Total Organic Carbon (TOC) analysis

Packaging Material Selection Case Study

A company was developing an oral suspension that showed color change during 6-month stability. The root cause analysis revealed that antioxidants in the HDPE bottle were reacting with the dye in the formulation. Switching to an inert PET container with internal lacquer coating resolved the issue. This emphasizes the importance of thorough compatibility testing in real formulations—not just with placebos.

Tips to Minimize Compatibility Risks in Packaging Development

• Use pre-qualified and pharmacopeial grade materials
• Choose coatings or inert barrier layers for reactive APIs
• Minimize surface contact with product (e.g., tip-seal devices)
• Simulate worst-case storage and shipping conditions early
• Consult packaging suppliers for historical data on interactions

Always factor in packaging interaction risks during process validation and product development lifecycle.

Documenting Material Compatibility in Regulatory Filings

In CTD Module 3, regulators expect a detailed justification of the packaging selection. Key documentation includes:

• Material composition and supplier data
• Summary of extractables and leachables testing
• Compatibility study protocol and outcomes
• Correlation with long-term stability data

Failure to provide compatibility data can result in deficiency letters or delayed product approvals.

Conclusion

Material compatibility is a foundational consideration in pharmaceutical packaging, especially for stability studies. By understanding the nature of packaging-drug interactions and proactively conducting analytical evaluations, pharmaceutical companies can ensure product safety, stability, and regulatory compliance. Compatibility studies are not a regulatory checkbox—they are a vital risk mitigation strategy for high-quality drug delivery.

References:

• USP General Chapter : Assessment of Extractables
• ICH Q3D Guideline on Elemental Impurities
• FDA Guidance for Industry: Container Closure Systems for Packaging Human Drugs and Biologics
• WHO Technical Report Series on Pharmaceutical Packaging Materials
• EMA Guideline on Plastic Immediate Packaging Materials