Extractable and Leachable Testing: Ensuring Safety and Compliance

Last Updated: May 2026. This article has been substantially updated to include the SCT, QT, and AET safety threshold framework central to all modern E&L programs; ICH Q3E (the primary international harmonized E&L guideline); ISO 10993-18:2020 for medical device chemical characterization; and the USP <665> mandate for single-use systems (effective May 2026).

Why E&L Testing Is Mandatory, Not Optional

When a pharmaceutical product is stored in a plastic container, delivered through an inhaler, or infused via a medical device, the packaging and delivery system is not inert. Polymers, adhesives, colorants, processing aids, and residual manufacturing chemicals can migrate into the drug product or food under storage and use conditions, exposing patients to potentially toxic substances at concentrations they never consented to or that were never evaluated in the clinical program. Extractable and leachable (E&L) testing is the analytical and toxicological program that identifies these compounds, quantifies them, and establishes whether they present an unacceptable safety risk.

Regulators do not treat E&L testing as optional. The FDA requires E&L characterization for all pharmaceutical and biopharmaceutical products, all medical devices and drug delivery systems, and all packaging materials in contact with drug products. EMA and ICH have issued harmonized guidelines. ISO has a dedicated standard for medical device chemical characterization. And as of May 2026, USP <665> is mandatory for single-use systems used in biopharmaceutical manufacturing. ContractLaboratory.com connects pharmaceutical companies, medical device manufacturers, food producers, and biopharmaceutical organizations with accredited toxicology and biocompatibility testing laboratories and chemistry and compound analysis specialists for E&L program support.

For the broader pharmaceutical packaging testing context, see our guide to pharmaceutical package testing. For polymeric material characterization, see polymers, plastics, and rubber testing.

Extractables vs Leachables: A Precise Distinction That Drives Study Design

The distinction between extractables and leachables is not semantic. It determines the study design, extraction conditions, analytical approach, and regulatory documentation required.

• Extractables: Compounds that can be released from a packaging component, container closure system, or medical device material under exaggerated (stress) conditions in the laboratory, using aggressive solvents (organic solvents, extremes of pH, elevated temperatures). Extractable studies are performed on the material in isolation, before the drug product is manufactured, to provide a worst-case profile of compounds that could potentially leach under any conditions. Extractable studies are typically the starting point for any E&L program.
• Leachables: Compounds that migrate from a material into the actual drug product, food, or biological fluid under normal conditions of storage and use. Leachable studies use the actual formulation (or a representative simulation solvent calibrated to match formulation polarity and pH) under ICH stability storage conditions. Leachable concentrations are always lower than extractable concentrations because real-use conditions are less aggressive than stress extractions.
• Simulation solvents: When conducting extractable studies for pharmaceutical applications, simulation solvents are chosen to bracket the polarity and pH of the intended formulation. Common simulation solvents include: purified water (polar, aqueous); 0.1N HCl or 0.1N NaOH (acidic or basic aqueous); 50% ethanol or isopropanol in water (intermediate polarity, simulating formulations with co-solvents); hexane (non-polar, for lipophilic formulations). The simulation solvent selection is documented and justified in the E&L study protocol.

The relationship between extractables and leachables is captured in the extractables-to-leachables bridge — a risk-based assessment that evaluates which extractable compounds are plausible leachables based on their physicochemical properties (polarity, molecular weight, volatility), the nature of the formulation contact, and the storage conditions. Not all extractables become leachables; but all leachables should be anticipated from extractable data if the study design is adequate.

What Are the SCT, QT, and AET — and How Do They Drive Testing Decisions?

The three safety thresholds that define modern E&L programs were established by the PQRI (Product Quality Research Institute) Working Group for Orally Inhaled and Nasal Drug Products (OINDPs) and subsequently adopted across USP, ICH Q3E, and ISO 10993-18 for other product types. Understanding these thresholds is essential for designing an E&L program that satisfies regulatory reviewers, because they determine what must be reported, what must be toxicologically qualified, and what can be considered below concern.

• SCT (Safety Concern Threshold): The concentration or daily exposure level below which a leachable is not expected to pose a mutagenic or non-mutagenic toxicity concern, regardless of its chemical identity. The SCT is route-of-administration dependent. For inhaled products, the SCT has been published by PQRI as 0.15 mcg/day for non-mutagenic concerns; for parenteral products, the SCT is 1.5 mcg/day. Compounds detected at or below the SCT do not require toxicological qualification in the submission, although they must still be detected and reported if they exceed the AET.
• QT (Qualification Threshold): The threshold above which a leachable is reported and must be toxicologically evaluated and qualified (i.e., acceptable limits established). Below the QT, a leachable may still be reported but does not automatically require full toxicological qualification unless structure-activity relationship (SAR) concerns exist (e.g., the compound has structural alerts for mutagenicity). The QT is set above the SCT, reflecting the distinction between safety concern levels and regulatory reporting levels.
• AET (Analytical Evaluation Threshold): A calculated, method-specific concentration threshold that defines the lowest concentration at which a leachable or extractable compound must be detected, identified, and reported. The AET is calculated from the SCT (or QT), adjusted for the daily dose of the drug product and an analytical uncertainty factor. The AET determines the minimum sensitivity required of each analytical method used in the E&L program. If an analytical method cannot reliably detect and quantify compounds at or below the AET for the specific product and dosing regimen, it is not adequate for that program. The AET calculation is required in regulatory E&L submissions and is specifically covered in ICH Q3E Appendix 3, USP <1663>, and ISO 10993-18.

In practice: for a parenteral drug product dosed at 10 mL per day, the AET for non-mutagenic leachables would be calculated from the SCT (1.5 mcg/day) divided by the daily dose volume (10 mL), adjusted by an uncertainty factor, yielding an AET in the ng/mL or low mcg/mL range — which in turn sets the minimum detection sensitivity required of the GC-MS, LC-MS, or ICP-MS methods used to screen the drug product.

Regulatory Framework: ICH Q3E, USP, ISO 10993-18, and the 2026 USP <665> Mandate

Multiple regulatory standards govern E&L testing, reflecting the diversity of products and markets. For multinational submissions, an integrated strategy addressing all applicable standards is essential.

ICH Q3E: The Primary International Harmonized E&L Guideline

The ICH Q3E Guideline for Extractables and Leachables is the product of international harmonization by the International Council for Harmonisation. It provides the foundational framework for E&L risk assessment and control for pharmaceutical products marketed in all ICH member regions (US, EU, Japan, and others). ICH Q3E covers: risk assessment methodology; AET calculation; leachable potency classification (Class 1: high potency, established limits; Class 2: low to moderate potency; etc.); requirements for extractable studies and leachable studies; reporting thresholds by route of administration; and the extractables-to-leachables bridge rationale. ICH Q3E is aligned with, and in some respects harmonizes, the USP <1663>/<1664> framework and ISO 10993-18.

USP Chapters for Pharmaceutical E&L

• USP <1663>: Assessment of Extractables Associated with Pharmaceutical Packaging/Delivery Systems. Provides guidance for conducting extractable studies, including extraction conditions, simulation solvents, and analytical method selection.
• USP <1664>: Assessment of Drug Product Leachables Associated with Pharmaceutical Packaging/Delivery Systems. Covers leachable study design, including stability samples, analytical methods, and reporting.
• USP <1664.1>: Leachables Testing of Aqueous-Based Inhalation Drug Products. Application-specific guidance for the highest-risk inhalation product category.
• USP <661>/<661.1>/<661.2>: Plastic Packaging Systems and their Materials of Construction. Governs physical and chemical characterization of plastic packaging materials and containers.

USP <665>: Single-Use Systems (Mandatory May 2026)

Regulatory Update: USP <665> mandatory from May 2026

• USP <665> (Plastic Components and Systems Used in the Manufacturing of Pharmaceutical and Biopharmaceutical Drug Products) became mandatory in May 2026.
• Organizations using single-use bioreactors, bags, tubing, and filters in biopharmaceutical drug manufacturing must now conduct E&L studies per USP <665>.
• The companion informational chapter USP <1665> provides guidance on study design and data interpretation for single-use systems.
• This is the most significant new E&L compliance requirement for biopharmaceutical manufacturing organizations in 2026. Review current single-use system suppliers for USP <665>-compliant E&L documentation.

ISO 10993-18:2020: Medical Device Chemical Characterization

ISO 10993-18:2020 — Biological Evaluation of Medical Devices — Part 18: Chemical Characterization of Medical Device Materials within a Risk Management Process — is the primary standard for E&L assessment of medical devices. It requires a risk-based approach to chemical characterization that considers: device material composition; route and duration of patient contact; the toxicological significance of detected compounds; and the AET calculation for medical device applications. The FDA draft guidance on biocompatibility for medical devices closely aligns with ISO 10993-18 and adds FDA-specific documentation requirements. The EU Medical Device Regulation (MDR 2017/745) also requires chemical characterization per ISO 10993-18 for devices requiring CE marking.

PQRI, BPOG, and Application-Specific Guidance

• PQRI (Product Quality Research Institute): Published the foundational safety thresholds for OINDPs (SCT, QT, AET framework). PQRI has also published guidance on parenteral SCTs, ophthalmic E&L considerations, and methodology for extractable studies.
• BPOG/BioPhorum: BioPhorum Operations Group has published industry guidance specifically for E&L testing of single-use systems in biopharmaceutical manufacturing, now referenced alongside USP <665> for supply chain and vendor qualification programs.
• EU Regulation 10/2011: The EU framework for plastic materials and articles intended to contact food. Establishes specific migration limits (SMLs) for listed substances and overall migration limits (OMLs) for unspecified substances, providing the European regulatory basis for food contact packaging E&L programs.
• FDA 21 CFR Parts 170-189: The US regulatory basis for food contact materials and indirect food additives, governing E&L programs for food packaging in the US market.

What Analytical Method Is Best for Your E&L Sample Matrix?

No single analytical method detects all extractables and leachables. An adequate E&L program combines multiple complementary techniques to ensure comprehensive coverage of volatile, semi-volatile, non-volatile, polar, non-polar, organic, and inorganic compounds. The AET for your specific product and dosing determines the required sensitivity of each method.

Method	Compound class	Approx. detection limit	Destructive?	Primary E&L application
GC-MS	Volatile and semi-volatile organics	Low ppb (ng/mL) range	Yes (headspace or solvent extract)	Plasticizers, antioxidants, processing residuals, residual solvents, aldehydes. Required screening method for most E&L programs.
LC-MS/MS	Non-volatile polar organics	Low ppb to ppt range	Yes (solution)	UV absorbers, stabilizers, polymer degradation products, oligomers. Complementary to GC-MS for full organic coverage.
ICP-MS	Elemental/inorganic (metals, metalloids)	Sub-ppb to ppt	Yes (acid digest)	Metal extractables per ICH Q3D and ISO 10993-18. Essential for devices with metal components or catalysts used in manufacture.
ICP-OES	Elemental/inorganic (multi-element)	Low ppb range	Yes (acid digest)	Multi-element metal screening. Lower sensitivity than ICP-MS but higher throughput; often used alongside ICP-MS for full elemental profile.
HPLC-UV/DAD	UV-absorbing organics	Mid ppb range	Yes (solution)	Semi-quantitative screening for UV-active leachables. Used for method development and for compounds not detected well by GC-MS or LC-MS.
FTIR / ATR-FTIR	Organic functional groups; polymer identification	Qualitative / semi-quantitative	No (ATR-FTIR non-destructive)	Identification of particulate matter, polymer type confirmation, surface analysis of device materials. Useful for unknown compound identification. See
NMR spectroscopy	Organic structure elucidation	High ppm to low ppb (concentration-dependent)	Yes (solution)	Structural identification of unknown extractables or leachables detected by GC-MS or LC-MS. Requires pre-concentration for low-level compounds.
TOC (Total Organic Carbon)	Total non-specific organic content	ppb range	Yes	Non-specific screen for total organic contamination in water-based extracts. Used for batch-to-batch comparison and as a first-tier screen before compound-specific analysis.

Container Closure Systems: The Primary Pharmaceutical E&L Application

The container closure system (CCS) — encompassing all packaging components that are in direct contact with the drug product, or in secondary contact but within the primary packaging environment — is the primary source of leachables in pharmaceutical products. E&L programs are built first and foremost around characterizing the CCS and establishing that its leachables profile is toxicologically acceptable at the patient’s daily exposure level.

CCS components requiring E&L assessment include: plastic bottles, caps, and caps liners; glass vials (type I borosilicate glass for injectables; delamination testing for susceptible formulations); rubber closures and elastomeric seals (stoppers, plungers, syringe components); aluminum crimp seals; plastic films and foils for blister packaging; multi-layer laminates for sachets and pouches; and adhesives, inks, and labels on primary packaging. Each component material type contributes its own extractable profile — rubber closures, for example, contribute vulcanization agents, accelerators, and antioxidants; while polyolefin plastics contribute antioxidants, slip agents, and processing stabilizers.

For pharmaceutical packaging testing beyond E&L (seal integrity, moisture vapor transmission, compatibility testing), see our companion guide. For polymers, plastics, and rubber material characterization, ContractLaboratory.com connects manufacturers with specialist laboratories.

Single-Use Systems: Biopharmaceutical Manufacturing E&L and the USP <665> Mandate

Biopharmaceutical manufacturing has shifted substantially toward single-use systems (SUS) — disposable bioreactors, culture bags, tubing, filters, and connectors — which contact drug substance intermediates and bulk drug substance during manufacturing. Unlike primary packaging, SUS contact may be brief (hours to days during upstream processing), but the materials (predominantly polyethylene, polypropylene, and silicone) do release extractables that can persist into the final drug product if not adequately characterized and controlled.

USP <665> (Plastic Components and Systems Used in the Manufacturing of Pharmaceutical and Biopharmaceutical Drug Products), which became mandatory in May 2026, establishes specific requirements for E&L characterization of SUS materials used in drug manufacturing. The companion chapter USP <1665> provides detailed guidance on: extractable study design for manufacturing-contact materials; selection of representative simulation solvents (including aqueous, acidic, basic, and organic); the AET calculation for manufacturing-contact applications (which differs from the direct patient-contact AET); and integration of supplier-provided extractable data with the manufacturer’s leachable monitoring program.

BioPhorum Operations Group (BPOG) published its Extractables Testing of Single-Use Systems guidance, which specifies a standardized extractable study protocol using five solvents (water, 0.1N NaOH, 0.1N HCl, 50% ethanol, hexane) across a range of temperatures and time points. The BPOG protocol has become the industry reference standard for SUS supplier E&L data packages, enabling biopharmaceutical manufacturers to evaluate and compare supplier-generated data using a consistent methodology.

The Risk-Based E&L Assessment Approach

Modern regulatory agencies explicitly require a risk-based approach to E&L assessment — not a reflexive exhaustive testing program, and not a minimal screening program. Risk factors that drive the scope and rigor of an E&L program include:

• Route of administration and patient exposure: Parenteral (intravenous, intramuscular, subcutaneous, intrathecal) and inhaled drug products have the highest E&L risk because compounds bypass first-pass metabolism and have direct systemic or pulmonary exposure. Oral products have lower risk because gut absorption and first-pass metabolism reduce effective exposure for many leachables. Topical, transdermal, and ophthalmic products have intermediate risk. Risk matrices in ICH Q3E and ISO 10993-18 use route, duration, and patient population as the primary axes of risk stratification.
• Duration and frequency of contact: A device implanted for years (orthopedic implant, cardiovascular device) requires a more comprehensive E&L characterization than a device used for minutes (surgical sponge). ICH classification categories: Limited (less than 24 hours); Prolonged (24 hours to 30 days); Permanent (more than 30 days).
• Nature of the material: New or novel polymer formulations, complex multi-layer laminates, and materials manufactured with unknown or variable additive packages carry higher extractable uncertainty than well-characterized materials with published extractable data. Prior history of safe use with specific drug formulations is a valid risk-reduction factor.
• Drug product formulation: Formulations containing organic co-solvents (propylene glycol, polyethylene glycol, ethanol), surfactants (polysorbate 80), or acidic/basic excipients have higher leachable potential than simple aqueous or saline formulations because these components enhance extraction of lipophilic or pH-sensitive material compounds.
• Patient population: Pediatric, geriatric, and immunocompromised patients may have higher vulnerability to specific leachables. E&L programs for pediatric drug products apply additional safety margins.

A well-designed risk assessment documents these factors explicitly, justifies the AET applied, selects simulation solvents based on formulation bracket analysis, and identifies which detected compounds require toxicological qualification vs which fall below concern thresholds. Early engagement with regulators (FDA, EMA) on E&L study design is strongly encouraged by ICH Q3E and PQRI for novel or complex products.

E&L Testing for Medical Devices Under ISO 10993-18:2020

For medical devices and drug delivery systems, E&L assessment is part of the broader biological evaluation required by ISO 10993-1 and ISO 10993-18. The chemical characterization process under ISO 10993-18 requires:

• Materials inventory: Complete disclosure of all materials of construction, including base polymers, additives, processing aids, and colorants. The chemical identity of each constituent must be established.
• Extractable study design and AET calculation: ISO 10993-18 requires extraction conditions calibrated to the device’s intended use conditions (duration, contact surface area, simulated body fluid), along with an AET calculated from the device-specific patient exposure and the SCT. FDA’s Chemical List for Analytical Performance (CLAP) helps laboratories demonstrate method adequacy relative to the AET.
• Toxicological risk assessment (TRA): Each compound detected at or above the AET requires a TRA establishing whether patient exposure is below the tolerable intake (TI) derived from available toxicological data. ISO 10993-17 and ICH M7 (for mutagenic impurities) provide the risk characterization frameworks.
• Combination products: A drug-device combination (prefilled syringe, drug-eluting stent, autoinjector, nebulizer, metered-dose inhaler) must satisfy both the pharmaceutical E&L requirements (ICH Q3E, USP <1663>/<1664>) and the medical device chemical characterization requirements (ISO 10993-18). Both agencies expect a harmonized E&L strategy that addresses the combined risk from all material components. This is an area of active regulatory evolution, with FDA and EMA both emphasizing consistency of approach for combination products.

Finding an E&L Testing Laboratory

E&L testing requires a combination of high-sensitivity multi-detector analytical platforms, chromatographic expertise, toxicological assessment capability, and regulatory writing support. Key qualifications to verify when selecting a contract E&L laboratory:

• ISO/IEC 17025 accreditation covering GC-MS, LC-MS/MS, and ICP-MS methods — essential for regulatory submission credibility
• ICH Q3E and USP <1663>/<1664>/<665> method capability — the laboratory should demonstrate experience with AET calculation and compliant study design, not just instrument operation
• ISO 10993-18 experience for medical device applications, including in-use simulation study design and toxicological risk assessment capability
• Toxicological assessment capability — the E&L program is only complete with toxicological qualification of detected compounds. Some laboratories offer integrated analytical-plus-toxicology services; others partner with toxicology CROs
• Regulatory submission support — the laboratory should be able to provide E&L study reports formatted for CTD (Common Technical Document) submission to FDA, EMA, and other ICH markets

ContractLaboratory.com connects pharmaceutical, biotech, and medical device organizations with accredited toxicology and biocompatibility testing laboratories and chemistry and compound analysis specialists experienced in ICH Q3E, USP <665>, and ISO 10993-18 E&L programs.

Frequently Asked Questions About Extractable and Leachable Testing

Conclusion: E&L Testing as a Patient Safety Imperative

Extractable and leachable testing has evolved from a routine quality control check into a sophisticated, risk-stratified toxicological program governed by an increasingly harmonized global regulatory framework. ICH Q3E, ISO 10993-18:2020, USP <665> (mandatory May 2026), and the PQRI threshold framework collectively define a rigorous, science-based approach that protects patients from unacceptable chemical exposure from the packaging, delivery systems, and manufacturing contact materials associated with their medications and medical devices. The SCT, QT, and AET thresholds translate toxicological risk assessment into actionable analytical targets, enabling E&L programs that are both scientifically defensible and proportionate to the actual level of patient risk.

ContractLaboratory.com connects pharmaceutical, biotech, and medical device organizations with accredited toxicology and biocompatibility testing laboratories for E&L program support. Submit a testing request or contact our team.