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

Step 1: Define the Scope of Compatibility Testing

The first step is to understand the product’s formulation and identify risks posed by container materials:

• Is the product an aqueous, oily, or solvent-based solution?
• Is the drug molecule sensitive to moisture, oxygen, light, or pH changes?
• What are the potential interaction points—adsorption, leaching, permeation?

Define your testing strategy based on these risk factors. High-risk products (e.g., biologicals, injectables, low-dose formulations) require a more comprehensive evaluation.

Step 2: Select Container Materials for Evaluation

Common container materials include:

• Type I borosilicate glass (vials, ampoules)
• HDPE, LDPE, PET (bottles, droppers)
• PVC/PVDC (blister packs)
• Rubber stoppers and elastomeric closures

Collect material safety data sheets (MSDS), supplier specifications, and pharmacopeial compliance documents (e.g., USP or ).

Step 3: Design the Compatibility Testing Protocol

Structure your protocol to cover the following interaction risks:

• Adsorption: Active or excipient adheres to container surface
• Absorption: Product components migrate into the packaging
• Leachables: Container components leach into the product over time
• Permeation: Gases or moisture pass through the container
• Chemical Reaction: Material reacts with formulation ingredients

Refer to ICH Q1A(R2) and ICH Q3D when developing your protocol.

Step 4: Prepare Samples for Compatibility Studies

Fill the drug product into each container variant under aseptic or clean conditions. Label test groups clearly:

• Test Container A: e.g., Type I glass + bromobutyl stopper
• Test Container B: e.g., PET bottle + HDPE cap
• Control: Stored in inert material (e.g., Teflon or amber glass)

Perform initial characterization before placing on stability.

Step 5: Store Samples Under ICH Stability Conditions

Store containers under the following conditions:

• Long-term: 25°C ± 2°C / 60% RH ± 5%
• Accelerated: 40°C ± 2°C / 75% RH ± 5%
• Photostability (if applicable): As per ICH Q1B

Typical duration: 3, 6, and 12-month timepoints. Label and segregate samples carefully to prevent cross-contamination or misidentification.

Step 6: Perform Analytical Testing for Compatibility Indicators

At each stability point, test for:

• Assay and degradation products (HPLC, UV)
• pH, clarity, turbidity, color, odor
• Extractables and leachables (GC-MS, LC-MS, ICP-MS)
• Particulate matter, visible foreign bodies
• Microbial growth (for aqueous or sterile products)

Compare results with acceptance criteria and control samples.

Step 7: Conduct Extractables and Leachables (E&L) Analysis

Extractables and leachables studies are crucial for identifying potentially harmful substances that migrate from container materials into the drug product. Follow these best practices:

• Perform extractables studies using aggressive solvents (water, ethanol, isopropanol, acid, base)
• Use orthogonal detection methods: GC-MS for volatiles, LC-MS for semi-volatiles, ICP-MS for metals
• Design leachables studies using real-time and accelerated stability samples
• Compare migration levels against ICH Q3D and USP thresholds

All data should be compiled in a compatibility risk assessment report for regulatory submissions.

Step 8: Evaluate Container Closure Integrity (CCI)

Container integrity should be tested using validated methods such as:

• Vacuum decay (non-destructive)
• Dye ingress (destructive visual method)
• Helium leak detection (quantitative)
• Microbial ingress (especially for sterile products)

Perform testing before and after exposure to thermal stress, vibration, and humidity to assess mechanical stability.

Step 9: Compile and Interpret Compatibility Study Results

At the end of the stability duration, compare test container results with controls. Interpret findings:

• Did any containers show significant degradation, adsorption, or leachable migration?
• Were assay values and impurity levels within specification?
• Did turbidity, precipitation, or odor changes occur?
• Was the CCI consistently maintained?

Only containers that meet all acceptance criteria and show no adverse interactions should be qualified for commercial use.

Step 10: Document the Compatibility Assessment

For GMP and regulatory compliance, your documentation should include:

• Compatibility testing protocol with rationale and objectives
• Material and container specifications
• Stability data tables and chromatograms
• Risk assessments and justification of container choice
• Signed reports reviewed by QA/QC

Include these documents in Module 3 of your regulatory submission and ensure alignment with the packaging section of the CTD.

Common Issues and How to Avoid Them

• Using data from placebo or water-based simulants only—always test real product
• Overlooking stopper or cap compatibility—evaluate all container components
• Skipping E&L testing for non-sterile products—regulators expect it for all container types
• Inadequate sample size or missing timepoints—follow ICH statistical requirements

Refer to GMP guidelines to ensure best practices are followed during execution.

Conclusion

Container compatibility testing is a vital step in ensuring pharmaceutical product stability, safety, and compliance. By following a structured, risk-based approach that includes analytical testing, E&L evaluation, CCI assessment, and thorough documentation, pharma professionals can confidently qualify packaging materials. These efforts not only support robust stability programs but also facilitate smoother regulatory submissions and market approvals.

References:

• ICH Q1A(R2): Stability Testing of New Drug Substances and Products
• USP : Assessment of Extractables
• USP : Container Closure Integrity Evaluation
• WHO Technical Report Series: Pharmaceutical Packaging
• FDA Guidance for Industry: Container Closure Systems

💡 Understand the Product’s Requirements First

The first step in selecting a container closure system is to understand the nature of the drug product:

• Is it sterile or non-sterile?
• Does it have sensitivity to light, oxygen, or moisture?
• Is the container under pressure or vacuum?
• What is the intended shelf life and storage condition?

Answering these questions ensures alignment between product needs and closure specifications.

📃 Follow Regulatory Expectations

Regulatory agencies such as EMA, USFDA, and WHO expect that the container-closure system used in stability studies be representative of the final market configuration. The closure must:

• Prevent ingress of gases, microbes, or contaminants
• Maintain sterility (for injectables and ophthalmics)
• Be evaluated using USP methods for integrity
• Undergo extractables and leachables (E&L) assessment

Ensure that closure selection is justified and supported by analytical data during dossier submission.

🔍 Assess Compatibility and Functionality

The selected closure must not react with or adsorb any component of the drug product. Conduct compatibility testing under ICH stability conditions. This includes:

• Evaluating closure integrity after thermal cycling
• Testing seal performance after autoclaving or irradiation
• Measuring resealability (for multi-dose containers)
• Observing closure appearance and odor during aging

Closures should be inert, consistent in performance, and mechanically stable under storage and transport stress.

Choose the Right Closure Materials

Use closure materials that align with the product’s storage and compatibility requirements. Common choices include:

• Butyl rubber stoppers: Excellent chemical resistance and resealability
• Silicone-coated closures: Ideal for proteins and low-adsorption formulations
• Aluminum flip-off seals: Tamper-evident, mechanical protection for stoppers
• Plastic caps: Used for non-sterile liquids or solids in bottles

Ask suppliers for data sheets, compliance certificates, and DMF references.

🔧 Best Practices in Sealing and Torque Validation

Proper sealing is as important as the closure itself. Use calibrated crimping or torque equipment and validate parameters:

• Monitor seal skirt depth and crimp diameter
• Perform pull-off force tests
• Document sealing equipment qualification
• Record torque specifications in packaging batch records

Improper sealing leads to integrity breaches and long-term product degradation.

📚 Maintain Strong Documentation and SOPs

Refer to SOP writing in pharma to create procedures for:

• Closure incoming inspection and quarantine
• Packaging line setup and verification
• Closure integrity testing and trending
• Deviation management for failed seals

Clear SOPs help minimize human error during closure handling and sealing operations.

📈 Validate Closures Under Accelerated and Long-Term Stability

Closures must retain performance under all ICH stability conditions:

• 25°C/60% RH (long-term)
• 30°C/65% RH (intermediate)
• 40°C/75% RH (accelerated)

Perform visual inspections, assay trending, microbial testing (for sterile products), and CCI assessments at each stability point. Ensure no signs of:

• Seal failure or loosening
• Cap corrosion or discoloration
• Stopper cracking or deformation
• Loss of sterility or product degradation

🔎 Monitor for Closure-Related Failures

Use deviation tracking systems to monitor closure-related issues during stability. Examples include:

• Weight loss in vials due to poor sealing
• Microbial growth from improper stopper resealability
• High variability in torque readings
• Stopper sticking or delamination

Trend data across different closure lots and implement CAPAs for recurring issues.

📊 Case Study: Flip-Off Cap Integrity in Humid Zones

A product was launched in a tropical market using aluminum flip-off caps without tropicalization. After 6 months in Zone IVb stability conditions (30°C/75% RH), caps showed corrosion and loose fitment. Root cause: lack of lacquer coating on the cap interior. Switching to anodized, coated caps resolved the issue. This case illustrates the importance of considering climatic stress when selecting closures.

📋 Summary of Best Practices

• Match closure type to drug sensitivity and route of administration
• Request E&L and regulatory data from closure vendors
• Conduct sealing process validation on commercial equipment
• Evaluate performance under stability conditions
• Include closure specification in regulatory filings
• Maintain robust SOPs for sealing and inspection

📖 Conclusion

Choosing the right container closure system is essential for ensuring pharmaceutical product integrity over its shelf life. Closures should be qualified not only for material compatibility but also for mechanical performance, integrity, and regulatory acceptability. By following these best practices, pharma professionals can reduce risk, maintain compliance, and confidently deliver safe and stable products to market.

References:

• USP : Container Closure Integrity Evaluation
• ICH Q1A(R2): Stability Testing of New Drug Substances and Products
• WHO Technical Report Series on Packaging and Closures
• EMA Guideline on Pharmaceutical Packaging Systems
• FDA Guidance for Industry – Container Closure Systems

How Packaging Materials Affect Outcomes in Accelerated Stability Testing

Accelerated stability testing is a vital tool for predicting drug shelf life — but its accuracy depends heavily on packaging material. Packaging serves as the first line of defense against moisture, oxygen, and light. Inappropriately selected packaging can lead to misleading accelerated data, affecting regulatory decisions and patient safety. This expert guide explores how different packaging materials impact stability outcomes and how to integrate packaging decisions into your stability strategy.

Why Packaging Matters in Stability Testing

Environmental stress conditions in accelerated studies (typically 40°C ± 2°C / 75% RH ± 5%) can rapidly expose weaknesses in a drug’s packaging. Materials that are insufficiently protective may allow ingress of moisture or oxygen, leading to exaggerated degradation and incorrect shelf life predictions.

Critical Roles of Packaging in Stability:

• Maintains drug integrity by providing barrier protection
• Controls product exposure to humidity and temperature
• Prevents contamination, evaporation, and interaction

Types of Packaging Systems Used in Pharma

The most common primary packaging formats used in stability studies include:

1. Blister Packs

• PVC (Polyvinyl chloride): Low barrier to moisture and oxygen
• PVC/PVDC: Improved moisture barrier
• Alu-Alu (cold form foil): Excellent barrier to light, moisture, and oxygen

2. Bottles and Containers

• HDPE Bottles: Common for tablets/capsules; moderate barrier
• Glass (Type I/II/III): Excellent inertness but may require desiccants
• Desiccant canisters/sachets: Added for moisture control

3. Sachets and Pouches

• Used for powders and granules
• Barrier properties vary by laminate composition

Barrier Properties and Their Influence on Stability

Each packaging material has a different Water Vapor Transmission Rate (WVTR) and Oxygen Transmission Rate (OTR). In accelerated studies, high temperature and humidity can stress packaging and reduce its protective efficiency.

Examples of Packaging-Induced Degradation

Case 1: PVC Blister Failure

A hygroscopic tablet stored in a PVC blister showed >5% assay loss and discoloration during a 6-month accelerated test. Switching to PVC/PVDC improved stability with impurities within limits.

Case 2: Alu-Alu vs HDPE

A photolabile drug showed degradation when stored in HDPE bottles without secondary light protection. Alu-Alu blisters maintained physical and chemical stability under the same conditions.

Packaging Design Considerations Before Stability Testing

1. Choose Based on Product Sensitivity:

• Moisture-sensitive APIs: Use PVDC-coated or Alu-Alu
• Oxidation-prone drugs: Require oxygen scavengers or inert atmosphere packaging
• Photolabile drugs: Require light-resistant containers

2. Match Packaging to Market Conditions:

• Zone IVa/IVb countries require high-barrier solutions
• Transport and storage conditions should be simulated

3. Include Packaging in Stability Protocol:

• Specify container-closure details in the study design
• Justify packaging choice scientifically
• Evaluate impact of secondary packaging where applicable

Regulatory Expectations and Documentation

Agencies such as USFDA, EMA, CDSCO, and WHO expect stability studies to be conducted using the final market-intended packaging. Any deviation must be justified.

Submission Inclusions:

• Packaging configuration in CTD Module 3.2.P.7
• Stability data in Module 3.2.P.8.3
• Photographs, cross-sectional diagrams (optional but useful)

Testing Packaging Impact in Accelerated Studies

For new drug products or packaging changes, conduct comparative accelerated studies across multiple packaging configurations to identify the optimal choice.

Design Tips:

• Compare PVC, PVDC, and Alu-Alu in parallel
• Evaluate multiple batches to ensure repeatability
• Measure WVTR and correlate with degradation data

Integration into Quality Systems

Packaging material selection should be governed by a cross-functional team involving formulation, analytical, regulatory, and quality assurance departments.

Documentation and QA Systems Should Include:

• Packaging specifications and supplier certifications
• Qualification reports and material compatibility studies
• Packaging impact assessments in stability protocols

For SOP templates and regulatory submission formats on packaging-integrated stability studies, visit Pharma SOP. For real-world case studies and packaging optimization guides, refer to Stability Studies.

Conclusion

The outcomes of accelerated stability studies are significantly influenced by the packaging material used. Selecting the right packaging is not just a logistical or aesthetic decision — it directly impacts drug product stability, shelf life, and regulatory acceptance. By incorporating packaging considerations early into study design and aligning with climatic zone requirements, pharmaceutical professionals can ensure accurate, reliable, and compliant stability outcomes.