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