IQ/OQ/PQ qualification of a GMP instrument: a practical guide to DQ, IQ, OQ, PQ

What "qualifying" an instrument means in GMP

In a pharmaceutical plant it is not enough for a piece of equipment to work: you must demonstrate with documented evidence that it is fit for the intended use and that it continues to be so over time. This is the meaning of qualification. It is not a one-off technical acceptance test, but a process that generates the documents on which, in an FDA or EMA inspection, confidence in product quality rests.

Qualification applies to plants, utilities and equipment (autoclaves, climatic chambers, fume hoods, HVAC systems, freeze dryers, tablet presses). For critical measuring instrumentation it sits alongside calibration: qualification demonstrates that the instrument is suitable and well installed, calibration guarantees its accuracy over time. They are complementary, not alternatives — a point that often causes confusion and that we address separately in the article on the difference between calibration and qualification.

The four phases: DQ, IQ, OQ, PQ

The typical sequence is DQ → IQ → OQ → PQ. Some phases can be combined (for example IQ/OQ) when adequately justified and based on a risk assessment.

DQ — Design Qualification

The design qualification verifies, before purchase or construction, that the design of the equipment meets the user requirements (URS) and the applicable regulations. It is the phase in which errors are intercepted when they cost the least: on paper, not on the shop floor.

IQ — Installation Qualification

The installation qualification documents that the equipment has been correctly installed and in conformity with the manufacturer's and user's specifications. It typically verifies:

• correspondence between the equipment delivered and the order/specifications;
• presence and correct positioning of the components;
• connection to the utilities (power, compressed air, water, steam);
• availability of manuals, diagrams, material certificates;
• calibration status of the critical instrumentation on board the machine.

OQ — Operational Qualification

The operational qualification demonstrates that the equipment operates as intended within the declared operating limits. Functions, alarms, safety interlocks, operating ranges and limit conditions (worst case) are tested. For an autoclave this means verifying the cycles; for a climatic chamber, the ability to maintain setpoint and uniformity; for a computerized system, the functions compliant with Annex 11 requirements.

PQ — Performance Qualification

The performance qualification confirms that, in real and repeated use, the equipment provides reproducible results compliant with the product quality requirements. It is the phase closest to the process: for a chamber it is typically performed over three consecutive compliant cycles; for a controlled environment, with representative loads.

The link with Annex 15 and GAMP5

Two references govern qualification in the European context:

• Annex 15 (Qualification and validation) of the EU GMP requires that critical equipment, plants and utilities be qualified, that the activities start from a Validation Master Plan and from clear user requirements, and that every phase be documented and approved. We go deeper into the specific requirements in the article dedicated to the Annex 15 requirements.
• GAMP5 provides the V-model that links each specification to the corresponding verification level (URS↔PQ, FS↔OQ, DS↔IQ) and the risk-based approach: the qualification effort concentrates where the impact on product quality and data integrity is greatest, avoiding testing everything in the same way.

When the equipment includes a computerized system, qualification integrates with Computer System Validation and with the data integrity requirements (Annex 11, 21 CFR Part 11, ALCOA+ principles).

How a qualification protocol is structured

A well-built protocol (IQ, OQ or PQ) always contains:

1. purpose and scope, with reference to the equipment and to the URS;
2. regulatory and documentary references;
3. responsibilities (who performs, who verifies, who approves);
4. prerequisites (for example: approved IQ before starting the OQ);
5. tests with acceptance criteria defined before execution;
6. recording of results, including any deviations;
7. management of deviations found during execution;
8. conclusions and final approval with signatures.

The non-negotiable principle: the acceptance criteria are written before running the test. A protocol in which the criterion "emerges" after seeing the result is not defensible in an audit.

Requalification and change control

Qualification does not end with the PQ. A piece of equipment must be requalified when something significant changes (a modification, a relocation, a major repair) or periodically based on risk. Every modification goes through change control, which assesses the impact on validation and establishes which phases to repeat. For temperature-controlled environments, thermal requalification is the typical periodic activity.

Who performs the qualification

Qualification can be carried out by the site's internal personnel or entrusted to a specialized technical partner, provided they are competent and operate according to documented procedures. In practice many sites rely on an external supplier for the field activities (protocol execution, periodic requalifications, smoke study), while keeping the approval and the GMP responsibility in-house. What to look for in a partner and which guarantees to require is the subject of the article on who can perform the qualification of a GMP instrument.

The Eurosystem experience

Eurosystem has operated since 1990 in regulated pharmaceutical sites. We execute qualification and requalification protocols for equipment, systems and utilities — including AFP smoke studies and thermal requalifications — with reference instrumentation whose metrological traceability is guaranteed through ACCREDIA-accredited laboratories. For us, qualification is not an isolated task: it integrates with calibration management (the Dimacs platform, over 11,000 instruments), automation and the site's change control, under a single partner that knows regulated environments from the inside.