CMC & ManufacturingLast reviewed April 2026

Critical Quality Attribute(CQA)

A physical, chemical, biological, or microbiological property of a drug substance or product that must be within an appropriate range to ensure quality.

Usage Examples

The drug substance CQAs included assay, related substances, residual solvents, and particle size distribution.
The CQA risk assessment was documented in Module 3.2.S.2.6 (manufacturing process development).
A new impurity at 0.12% was classified as a CQA requiring specification control.

What is CQA?

A Critical Quality Attribute (CQA) is a quality characteristic of a drug substance, drug product, or intermediate that must be within an appropriate limit, range, or distribution to ensure the desired product quality. The concept comes from ICH Q8 and is central to the Quality by Design (QbD) framework: CQAs are the measurable bridge between the QTPP and the control strategy.

CQAs are identified through a risk assessment linking quality attributes to product performance and patient safety or efficacy. A typical small-molecule drug product has CQAs for identity, assay, content uniformity, dissolution, impurity profile, and microbial limits. A biologic adds CQAs for aggregates, charge variants, glycosylation patterns, bioactivity, and immunogenicity-relevant attributes.

Criticality is determined by the potential impact of a deviation on patient safety or efficacy. Attributes with moderate or high impact that cannot be perfectly controlled through process design become CQAs requiring release testing or in-process control. CQAs appear explicitly in the Module 3.2.S.4 specifications and Module 3.2.P.5 specifications sections of an eCTD submission.

Regulatory Context

This term appears most often in cmc & manufacturing workflows where submission quality, regulatory evidence, and audit readiness depend on consistent language. It is commonly referenced alongside ICH Q8, ICH Q9, ICH Q11.

FDAICHHealth Canada

When This Matters

The drug substance CQAs included assay, related substances, residual solvents, and particle size distribution.
The CQA risk assessment was documented in Module 3.2.S.2.6 (manufacturing process development).
A new impurity at 0.12% was classified as a CQA requiring specification control.

Common Mistakes

Failing to align CMC change narratives with current CFR/ICH expectations.
Submitting incomplete control strategy documentation.
Separating manufacturing and regulatory review cycles too late in execution.

Related Regulations

ICH Q8ICH Q9ICH Q11

Frequently Asked Questions

Quality attributes are any measurable property of a drug substance or product. CQAs are the subset of those attributes where a deviation could affect safety or efficacy — meaning they must be actively controlled within defined ranges. Non-critical attributes are monitored but not specification-controlled.

The sponsor identifies CQAs through a formal risk assessment during development, typically using tools like FMEA (Failure Mode and Effects Analysis). The assessment considers severity of impact, probability of occurrence, and detectability. Final CQA designations are documented in the CMC submission and evaluated during FDA review.

Yes. As manufacturing knowledge accumulates (through production experience, complaints, stability data, process changes), the CQA set may be revised. Changes require formal change control and potentially post-approval submissions (Prior Approval Supplements, CBE-30, or Annual Report) depending on impact.