Proficiency Testing for Canadian Pharmaceutical Labs: What ISO 17025 and Health Canada GMP Actually Require

Most Canadian pharmaceutical laboratories know they’re supposed to participate in proficiency testing programs. Fewer can explain, under audit pressure, exactly which ISO 17025 clause mandates it, how their z-score acceptance criteria are documented, or how those PT records map to Health Canada’s GMP lab control expectations under the Food and Drug Regulations. That gap tends to surface at the worst possible time — during a CALA assessment renewal, or an unannounced Health Canada GMP inspection.

This post is a practical reference for lab managers, quality directors, and regulatory affairs professionals at Canadian CROs, CMOs, and pharmaceutical manufacturers who need to get this right.

Why Proficiency Testing Is Not the Same as Internal QC

PT is routinely conflated with internal quality control — reference standard checks, system suitability runs, replicate testing, analyst training records. Those are all valuable, but they answer a fundamentally different question.

Internal QC tells you your method is running correctly today, in your lab, on your instrument, with your analysts. Proficiency testing tells you your results are accurate relative to what another qualified laboratory would obtain on the same sample. That’s an external check on whether your entire analytical system — method, materials, people — is producing results that agree with an independent reference point.

The distinction matters in a GMP context because a lab can pass every system suitability criterion for months and still carry a systematic bias in its analytical results that only an external comparison would catch. A poorly prepared working standard, a miscalibrated balance that hasn’t drifted far enough to trip internal alarms, a column aging gradually in ways your system suitability doesn’t measure — these are exactly the failure modes PT programs are designed to detect. Internal controls alone won’t find them.

ISO 17025:2017 Clause 7.7 — What the Standard Actually Says

ISO/IEC 17025:2017 is the international competence standard for testing and calibration laboratories, and Clause 7.7 — “Ensuring the Validity of Results” — is where proficiency testing is formally anchored.

Clause 7.7.1 requires that a laboratory have a documented procedure for monitoring the validity of its results. The standard identifies participation in proficiency testing or inter-laboratory comparison schemes as the primary external mechanism for doing so. This isn’t a recommendation; it’s a normative requirement. A CALA assessor reviewing your quality management system will expect to see both a PT participation procedure and evidence that PT rounds are being conducted.

Clause 7.7.2 goes further: monitoring data must be analyzed and used to control and, where applicable, improve laboratory activities. That word “analyzed” does real work. Filing PT certificates without trending the results, investigating outliers, or feeding findings back into your quality plan is not compliance — it’s paperwork theater.

The scoring framework underpinning virtually all accredited PT schemes globally comes from ISO 13528:2022, Statistical Methods for Use in Proficiency Testing by Interlaboratory Comparison. The z-score thresholds are:

• |z| ≤ 2.0 — Satisfactory
• 2.0 < |z| ≤ 3.0 — Questionable (investigation warranted)
• |z| > 3.0 — Unsatisfactory (CAPA required)

These aren’t arbitrary. The z-score is calculated as (x − X) / σ, where x is your result, X is the assigned value (typically the consensus mean or a reference value from a certified material), and σ is the standard deviation for proficiency assessment set by the PT provider. Scores in the questionable range don’t automatically require a CAPA, but they should trigger a documented review — and if two consecutive questionable scores appear on the same assay, that’s effectively an unsatisfactory trend that needs to be addressed.

Health Canada GMP Expectations — Where Lab Controls Live in the Regulations

Health Canada’s GMP requirements for drug manufacturers are codified in Part C, Division 2 of the Food and Drug Regulations — specifically sections C.02.018 through C.02.025, which collectively govern laboratory controls. GUI-0001, the Good Manufacturing Practices (GMP) Guidelines, is the document inspectors actually reference during audits, and Section 6 of GUI-0001 expands on laboratory control requirements in practice.

GUI-0001 doesn’t name proficiency testing explicitly. What it does require — and what experienced Health Canada inspectors probe in detail — is evidence that laboratory controls are adequate to ensure that drugs meet their established specifications. That adequacy determination covers:

1. Reference standards and reference materials appropriate to the testing being performed
2. Qualification and training of laboratory personnel — demonstrated competency, not just training records
3. Validated analytical methods that perform correctly under your lab’s specific conditions

PT participation and PT records directly support all three. A successful inter-laboratory comparison result is tangible, auditable evidence that your reference standard preparation is correct, your analysts are producing accurate data, and your validated methods perform in your hands the way they performed during validation. For NHP manufacturers operating under the Natural Health Products Regulations, the parallel requirement to test each lot prior to release carries the same implicit expectation that the lab doing the testing can demonstrate reliable results.

One nuance worth knowing: Health Canada’s inspectors are familiar with ISO 17025. Even when they’re conducting a GMP inspection rather than a lab accreditation assessment, they look at pharmaceutical labs through a competency lens that aligns closely with 17025 expectations. A lab that can point to recent PT records with analyzed trends, documented investigations for any questionable scores, and a clear link between PT performance and their QC SOP is in a fundamentally stronger position than a lab that can’t.

Selecting a PT Provider for Pharmaceutical Testing

CALA (the Canadian Association for Laboratory Accreditation) maintains a directory of recognized PT scheme providers that accredited laboratories can draw from. For pharmaceutical-relevant chemical testing — potency assays, dissolution, heavy metals, residual solvents — commonly used international providers include LGC EQAS, BIPEA, and FAPAS, all of which operate schemes that are recognized within ILAC’s (International Laboratory Accreditation Cooperation) mutual recognition arrangement. For microbiological testing, schemes such as QMPS or sector-specific collaborative studies are more appropriate.

Matching your PT scheme to your actual scope of accreditation is non-negotiable. A lab accredited for HPLC-based potency testing of natural health products should be running PT rounds that include at least one botanical marker or API assay. A lab with a microbiology scope needs microbiological PT — not just chemical. Misalignment between scope and PT coverage is a common finding during CALA assessments and one that’s straightforward to avoid with a little planning at the start of the calendar year.

On frequency: ISO 17025 doesn’t specify a minimum. CALA’s general benchmark, and what we’d consider defensible during a Health Canada lab audit, is at least once per year per major method category. For higher-risk testing — sterility, heavy metals, potency of narrow-therapeutic-index drugs — twice annually is a more defensible target. PT costs for pharmaceutical chemical assays typically range from $150 to $800 CAD per round; more complex biological matrices can run higher. Budget these in your annual laboratory quality plan, not as an afterthought.

When a PT Round Returns an Unsatisfactory Score

An unsatisfactory z-score (|z| > 3.0) is not a catastrophe. How a lab responds to it is what defines quality culture — and what Health Canada inspectors and CALA assessors actually evaluate.

Under both ISO 17025 Clause 7.10 (nonconforming work) and Health Canada GMP Section 6 requirements, a documented root cause investigation is mandatory for unsatisfactory PT results. Common root causes fall into a predictable set:

• Operator error during PT sample reconstitution or preparation (the most common finding)
• Reference standard degradation or mis-preparation of the working standard
• Method drift — column aging, reagent batch change, instrument recalibration offset
• Sample homogeneity issues in the PT material itself (rare, but PT providers do occasionally report these)

The root cause investigation has to be documented. But the step that labs most often handle poorly is what comes next: evaluating whether the unsatisfactory result has implications for previously reported results. If a systematic bias in your potency assay was present during the PT round, it was almost certainly present during the weeks or months of routine testing that preceded it. A CAPA that addresses the root cause but ignores retroactive impact is incomplete — and that’s precisely the gap Health Canada inspectors and CALA assessors probe when they review a PT-related nonconformance.

The retroactive impact assessment doesn’t always result in sample retesting. Often the investigation concludes that the root cause was a one-time preparation error with no bearing on previous routine samples — and that’s a defensible conclusion if the investigation is thorough and documented. The failure mode is skipping the assessment entirely.

Building PT into Your Annual Quality Plan

The most effective approach is to schedule PT participation at the beginning of each calendar year, not on an ad hoc basis. Map PT rounds to your scope of accreditation, assign a PT coordinator (one analyst who owns the logistics, sample preparation, and result submission for each scheme), and define in your procedure how z-scores will be reviewed, trended, and reported to lab management.

Trending is underused. A lab that consistently scores z = +1.8 on a given scheme — technically satisfactory — should be asking why its results trend systematically high. A z-score of +1.8 sustained over four consecutive rounds suggests a consistent positive bias, likely in reference standard preparation or analyst technique. Catching that before the score crosses 3.0 is what a mature quality system looks like. Build a simple trend chart into your PT review procedure: plot z-scores by scheme and analyte over time, and flag any trend of three or more consecutive scores in the same direction, regardless of whether any individual score is unsatisfactory.

Finally, if your organization outsources any testing to a contract laboratory, request their PT participation records for the relevant test methods before awarding the work. Any reputable contract research organization in Canada operating under ISO 17025 accreditation should be able to provide recent PT results, scheme provider details, and any investigations related to unsatisfactory rounds. If they hesitate or can’t produce these records promptly, treat that as a meaningful signal about the maturity of their quality system.

Before Your Next Audit

Review your lab’s PT schedule and records against three specific criteria. First, confirm you have at least one completed PT round per major method category within the past 12 months. Second, verify that any questionable or unsatisfactory results have documented investigations — with retroactive impact assessments where required. Third, check that your procedure defines not just how to participate in PT rounds, but how you trend z-scores over time and what triggers an escalation to lab management.

Those three things are the difference between a lab that passes its audits and a lab that collects repeat findings on the same issue.

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Written by Nour Abochama, Quality & Regulatory Advisor, Androxa. Learn more about our team

Talk to our team about Health Canada compliance. Contact us

Related from our network

• ISO 17025-Accredited Supplement and Pharmaceutical Testing — Qalitex Laboratories offers accredited analytical testing for US-market pharmaceutical and NHP products, with full method validation documentation.
• EU GMP and ISO 17025 Lab Compliance for European Market Entry — Care Europe covers EU regulatory requirements for manufacturers seeking to demonstrate laboratory competency under EMA and EU GMP frameworks.