Container Closure System Deficiencies in FDA NDA and BLA Reviews: Recurring Themes and Evolving Expectations Since 1999

Container closure system deficiencies in FDA reviews and inspections, and how expectations have evolved since the 1999 guidance

Container closure system (CCS) problems are among the most durable and predictable deficiency themes in FDA drug and biologics regulation. They surface at every stage of the lifecycle: as information requests and CMC review comments during NDA/BLA assessment, as reasons for non-approval in Complete Response Letters, and as CGMP citations in Form 483 observations and warning letters. The substance of what FDA expects still traces back to the framework in the 1999 guidance Container Closure Systems for Packaging Human Drugs and Biologics, but the depth, specificity, and analytical rigor demanded have increased markedly since then.

The 1999 framework: four suitability criteria

FDA's 1999 guidance frames CCS acceptability around four suitability criteria: protection, compatibility, safety, and performance (drug delivery) ¹³⁷¹³⁹¹⁵⁴. In practice:

Protection: the system must protect the product, including maintaining container closure integrity and providing a barrier against microbial ingress or leakage ¹³⁷¹³⁹¹⁵³¹⁵⁴.
Compatibility: the drug product must be physically and chemically compatible with the packaging materials, assessed through compatibility and stability data ¹³⁵¹³⁷¹⁴²¹⁴⁶¹⁵¹¹⁵⁵.
Safety: the system must not introduce harmful substances, which is where extractables/leachables (E&L), biological reactivity, and toxicological evaluation of migrating species come in, with the highest concern for injectables ¹⁴⁰¹⁴²¹⁴⁴¹⁵⁵¹⁵⁶.
Performance/drug delivery: where the container also functions as a delivery system, it must perform as intended, covering dose accuracy, break-loose and glide force, and syringe/pump compatibility ¹³⁷¹⁵⁴.

The 1999 guidance calibrated the depth of information to the dosage form and route: injectables carry the highest leaching concern and require the most complete E&L, integrity, sterility, and device-function data ¹⁴⁰¹⁴⁴¹⁵³¹⁵⁴; oral solid dosage forms could often be supported by USP <661>/<671> packaging testing ¹³⁶; dry powder inhalers carry lower leachables risk than liquid inhalers but still require E&L assessment of critical components ¹⁴¹; and topical/semisolid products in foil laminates or pouches require material identification and E&L information for the product-contact layer ¹⁴³¹⁵⁵.

Recurring deficiency 1: container closure integrity

Container closure integrity (CCI) is the single most recurrent CCS deficiency across all document types.

In CRLs, integrity failures have repeatedly driven non-approval. FDA has rejected proposed CCI test methods for poor defect detection and failure to correlate with microbial ingress, asking for validated CCIT demonstrating integrity of glass ampules and the packaging pouch ⁸⁰; required a prefilled-syringe microbial-ingress method to be run under both pressure and vacuum rather than vacuum alone ⁸⁸; asked scPharmaceuticals for positive/negative controls and a limit of detection for a dye-ingress method ⁸³; cited reproducibility problems in Braeburn's visual CCIT analysis and asked for an alternative quantitative method or sterility testing ⁹³; told Evolus it had not demonstrated that worst-case vial sealing parameters supported integrity ⁸⁶; and told MediWound its CCIT validation could not detect 20-micron leaks and needed revised validation demonstrating detection of all breaches below 20 microns ⁸².

In CMC reviews and information requests, FDA asks for CCIT data able to detect breaches and prevent microbial ingress, and repeatedly finds proposed integrity or leak tests insufficiently sensitive or incapable of timely leak detection ²⁰⁴²⁰⁵²¹¹²²²²²⁵. Reviewers frequently ask that the method be validated against microbial ingress rather than physical-defect detection alone, with full method descriptions, controls, acceptance criteria, and results ²⁰⁴²¹⁷²²⁵. Where a system is claimed to be commercial, FDA still asks for supporting qualification data or justification that the tested system matches the marketed one ²⁰⁶²¹⁰²¹¹.

In Form 483s, recurring observations include CCIT not performed or performed with inadequate methods (for example, testing empty vials or media rather than filled product) ²⁶⁵²⁶⁷²⁷⁰²⁷⁵²⁷⁹²⁸³; leak/seal testing gaps and unvalidated leak testers ²⁶¹²⁷³²⁸³; seal and crimp defects such as loose or partially crimped seals, aluminum seals coming off, leaks between cap and vial, and pinhole leaks ²⁶¹²⁶⁸²⁷⁴²⁸¹; capping/sealing process validation gaps ²⁷³²⁷⁸²⁸³; and missing positive controls or defect kits for CCIT and inspector qualification ²⁶²²⁷⁰²⁷⁶.

In warning letters, FDA cites leaking containers released or distributed despite observed leaks ¹⁶⁷¹⁶⁹¹⁰³¹⁷⁷; absent or inadequate CCI validation with no reliable evidence the system maintains sterility over shelf life ¹⁶⁷¹⁶⁹¹⁷⁷¹⁸³; failure to detect or investigate closure defects such as poorly fitting caps, plugs, seals, or membranes ¹⁰³¹⁷⁴¹⁷⁷¹⁸⁰; leaks discovered in media fills, indicating the process does not reliably produce integral units ¹⁶⁷¹⁷²; and dye-ingress or other CCI methods with inadequate sensitivity, including a case where the method was not shown sensitive enough to detect organisms comparable to Pseudomonas aeruginosa ¹⁶⁹¹⁷⁷.

Recurring deficiency 2: extractables and leachables

E&L characterization is the other dominant theme, and it is where FDA's expectations have become most prescriptive.

Across CRLs, FDA has repeatedly found E&L packages inadequate: Recro Pharma's leachables program targeted too few compounds and did not monitor all extractables/leachables above threshold, including unknowns ⁶²⁶⁴; Braeburn's extractables studies did not use sufficiently exhaustive conditions and its leachables profile was incompletely characterized ⁶³; Adamis, Heron, Innocoll, IBSA, InnoPharma, Lannett, Xellia, and AFT all received CRLs tied to incomplete leachables identification, inadequate extractables-to-leachables correlation, too few batches or timepoints, or missing toxicological risk assessment ⁶⁶⁶⁷⁷⁰⁷¹⁷²⁷⁷⁷⁸⁷⁵. A consistent expectation is identification of unknown compounds above 5 mcg/day and a toxicological risk assessment based on the maximum leachable level over shelf life ⁶⁶⁶³⁶²⁸⁷⁶⁴⁷⁰.

FDA reviews articulate a stable, risk-based E&L expectation: adequate extractables information with justified solvents and conditions; a definitive leachables stability program using at least three batches at multiple timepoints; inclusion of any secondary CCS and, where relevant, upstream process-contact materials; matching sterilization conditions; identification and quantitation of compounds above the relevant threshold; and a toxicological risk assessment tied to the maximum predicted leachable level ²³⁵⁶⁷¹¹¹³¹⁶²⁰²²²⁵. On analytical sensitivity, FDA expects the analytical evaluation threshold (AET) to be set to detect genotoxic/carcinogenic concerns under ICH M7, and for parenteral products expects methods able to detect and identify any leachable at 5 mcg/day or higher unless justified ²³⁵⁶⁷¹¹¹²¹³¹⁵¹⁶¹⁷²⁰²¹²². Common review deficiencies include insufficient stability leachables coverage, unidentified unknowns above threshold, monitoring only a subset of extractables, inadequate AET methodology, and use of routine release/stability assays where broader orthogonal methods (HPLC-UV-MS, headspace GC-MS, GC-MS, ICP-MS) are needed ⁵⁶¹⁶²⁰²²⁹²⁵.

Recurring deficiency 3: elemental impurities versus organic leachables

FDA reviews treat elemental impurities and organic leachables as related but distinct. Elemental impurities from the CCS are assessed under ICH Q3D against route-specific PDEs, and when measured levels sit below the PDE or the 30% control threshold, no routine additional control is required ²³³²³¹²³⁹²³². Organic leachables are handled outside Q3D using leachable-specific thresholds (AET/SCT/TTC) and toxicological qualification; one review states explicitly that ICH Q3D is limited to elemental impurities and does not apply to organic extractables and leachables, and requested identification and qualification of organic compounds above the AET/SCT ¹⁰. This two-track framework applies to prefilled syringes and device-associated systems as well, with syringe components, plungers, stoppers, and adapters evaluated for both elemental and organic species ²³³²³⁴²³⁵²³⁹²⁴³¹⁰.

Recurring deficiency 4: glass container quality and delamination

Glass quality has become a discrete review concern. The lenacapavir injection reviews are a clear example: FDA found the drug product solution incompatible with borosilicate glass vials, with degradation of the vial surface and glass particles in solution ¹⁸⁹¹⁹⁸²⁰², linked to the product's high pH (9 to 10) and a history of glass particle contamination ¹⁹⁸²⁰¹. FDA described borosilicate incompatibility leading to glass lamellae formation and significant pitting, noted unexplained particles in clinical batches, and stated that the role of glass particulates in injection-site reactions was unclear ¹⁸⁷¹⁸⁹²⁰¹. The applicant moved from borosilicate to aluminosilicate vials, and FDA required a comprehensive validated compatibility study, ongoing stability through expiry, more complete CCIT, and labeling to inspect for particulates ¹⁸⁸¹⁸⁹¹⁹²¹⁹⁸²⁰². The broader concern for glass containers has centered on surface degradation, pitting, delamination, and particle shedding rather than outright vial breakage ¹⁸⁷¹⁸⁹¹⁹⁸²⁰².

Recurring deficiency 5: elastomeric closures, component control, and seal/crimp defects

Rubber stoppers and other closure components recur in both review and enforcement records. In CRLs, FDA has required extractable studies on drug-product and gel-vehicle rubber stoppers ⁷³ and held that a stopper's acceptability could not be determined until its leachables were identified and their safety assessed ⁷⁸. Form 483s cite the absence of E&L studies for specific closures, including 13 mm and 20 mm stoppers used with allergenic extract vials ⁹⁷, and for plastic/PS bottle containers ⁹⁸¹⁰⁰¹⁰¹.

Warning letters emphasize the CGMP component-control chain: failure to control incoming containers and closures, to withhold each lot until sampled/tested/released by the quality unit, to establish scientifically sound specifications and inspection programs, and to maintain an adequate quality unit responsible for accepting or rejecting containers and closures ¹⁰²¹⁰⁵¹⁰⁹¹¹⁰¹¹³¹¹⁵¹¹⁷¹¹⁹¹²⁰¹²³¹²⁴¹²⁶. Specific closure defects cited include defective bag-port membrane closures, inadequately fitting or unattached caps, non-integral closures from improper component placement during filling, and cracked closure components that appear only after standing ¹⁰³¹⁰⁴¹¹⁸. Supplier qualification failures, such as accepting closure certificates of analysis without verifying supplier testing, recur across both warning letters and inspections ¹⁶⁷¹⁷⁷¹⁷⁸.

Recurring deficiency 6: combination products and delivery devices

For prefilled syringes, cartridges, and autoinjectors, the primary container closure (staked-needle syringe with rigid needle shield and plunger stopper) is often paired with a device constituent such as a safety mechanism, autoinjector housing, or firing mechanism ²⁸⁹²⁹¹²⁹²²⁹⁸³⁰⁰³⁰¹³⁰⁷. Recurring deficiencies and information requests include inadequate data supporting needle-safety activation and override forces, and device performance across shelf life ³¹¹; and repeated deferral of primary-container attributes (container content, break-loose and glide force, needle shield removal force, sterility, biocompatibility) and drug-device compatibility between the device review and CDER CMC review, which can leave those functions unresolved ²⁹¹²⁹⁴²⁹⁵³⁰¹³⁰²³⁰⁵³⁰⁶. Human factors and usability questions are commonly routed to CDRH human factors review rather than resolved in the device-constituent review ²⁹³²⁹⁶³⁰⁵.

How FDA expectations have evolved since 1999

The four suitability criteria endure, but the evidentiary bar has risen substantially:

Extractables and leachables have become far more prescriptive. Reviews from 2015 to 2017 expected an E&L assessment in broadly qualitative terms; by 2017 to 2020 the language hardened to at least three batches, multiple stability timepoints, inclusion of secondary CCS, explicit AET discussion, and identification of unknowns above threshold; from 2021 onward reviews standardize around explicit references to USP <1663>/<1664>, the FDA CCS guidance, and a defined 5 mcg/day parenteral detection/identification expectation; and 2023 to 2026 reviews additionally distinguish organic-E&L AET methodology from the ICH Q3D elemental approach and cite PQRI 2021 best practices ⁸⁹¹³⁵⁶¹⁵¹⁶²⁰²¹²²²³⁴¹²¹⁷¹⁰¹⁹¹.
Container closure integrity expectations have shifted from generic to method-specific and validation-driven. A representative review states that citing "USP <1207>" alone is no longer sufficient; FDA wants the specific method used (dye ingress, microbial ingress, vacuum decay, and similar), with acceptance criteria that distinguish integral from non-integral units, plus validation data and a limit of detection ²⁸⁸. For blow-fill-seal primary containers the Agency expected 100% leak testing with a reliable, sensitive, validated method ²⁸⁸. This reflects a broader move toward concrete, deterministic, validation-based CCI evidence.
Elemental impurities were folded into a distinct ICH Q3D track, separate from organic leachables, with route-specific PDEs and the 30% control-threshold concept now standard in CCS risk assessments ²³³²³¹²³⁹¹⁰.
Glass delamination and particulate shedding became a defined review concern, with FDA requiring validated compatibility studies, alternative glass types (e.g., aluminosilicate), and postapproval stability confirmation where borosilicate incompatibility is plausible ¹⁸⁷¹⁸⁹¹⁹²¹⁹⁸²⁰².
Inspection and compliance-program expectations were extended and formalized. Sterile-drug inspection procedures direct investigators to verify incoming container/closure specifications (materials, dimensions, freedom from critical defects) and to assess CCI studies across sterilization, handling, storage, and shelf life, treating integrity as critical to maintaining sterility through use ²⁹. For outsourcing (503B) facilities, FDA states a CCI test should be used even where stability studies are absent or reduced, and requires lot-level examination of components/containers/closures or verification of supplier results ³⁰³¹. Preapproval inspection guidance for combination products defines the container closure as the sum of packaging components that contain and protect the drug constituent, brings prefilled-syringe components under 21 CFR 211.84, and directs sampling/testing evaluation of drug-constituent components, containers, and closures ⁴⁰⁴⁸.

Practical implications

The pattern for regulatory affairs and CMC teams is consistent. Integrity claims must rest on a specifically named, validated, appropriately sensitive CCIT method with defined acceptance criteria, not a generic USP <1207> reference ²⁸⁸²⁰⁴. E&L packages for parenteral and biologic products should be built proactively to the now-standard expectations: justified exhaustive extraction, a definitive leachables stability program over at least three batches and multiple timepoints, inclusion of secondary CCS and process-contact materials, an AET sensitive to genotoxic/carcinogenic risk and typically 5 mcg/day for parenterals, identification of unknowns above threshold, and a worst-case toxicological risk assessment ²³⁵⁶¹⁶²⁰²²²⁵. Elemental impurities should be documented against ICH Q3D as a separate track ¹⁰²³³. Glass compatibility, especially for high-pH formulations, and elastomeric closure suitability should be qualified early, before delamination or unidentified leachables become a review-cycle or CRL problem ¹⁸⁷¹⁸⁹⁷⁸⁷³. And for combination products, primary-container functional attributes and drug-device compatibility should be resolved rather than left to bounce between device and CMC review disciplines ²⁹¹²⁹⁴³¹¹.