Pharmaceutical Facility URS and Design Basis: From Requirements to DQ

Every qualified facility rests on a simple chain: the owner states what is required, the designers state how they will meet it, and someone checks, with evidence, that the design does meet it. On pharmaceutical projects these three steps are usually called the user requirements specification (URS), the design basis, and design qualification (DQ).

EU GMP Annex 15 and similar guidance from PIC/S and WHO describe qualification as starting from user requirements, and ISPE guidance on commissioning and qualification describes a science- and risk-based way of applying it. This article looks at the practical side: what goes into each document and how they connect.

The URS: what the owner needs

The URS belongs to the owner. It states what the facility, system or equipment must do and the conditions it must meet, without prescribing the engineering solution unless there is a reason to. A facility URS typically covers:

• Products, dosage forms, batch sizes, capacity and shift pattern, including expected future growth.
• Process steps and the conditions each needs: open or closed handling, cleanliness, containment, temperature and humidity.
• GMP and regulatory basis: the markets, frameworks and inspections the facility must be ready for.
• Utilities: water grades and use points, clean steam, compressed air and gases, with quality and capacity.
• Automation, monitoring and data integrity expectations, including alarms and records.
• Health, safety and environmental requirements, including occupational exposure where relevant.
• Operability and maintenance: access, cleaning, spare parts and the owner’s maintenance capability.
• Constraints: site, budget, schedule, existing buildings or systems that must be reused.

What makes a good requirement

A useful requirement is unique, clear, verifiable and justified. Each one has an identifier, a statement that can be tested or inspected, a priority or criticality, and a source — a regulation, a product need, a process need or an owner preference. Requirements that affect product quality or patient safety should be identifiable as such, because they will receive the most attention in qualification. "The room must be easy to clean" is a wish; a statement of required finishes, junction details and compatibility with the intended cleaning agents is a requirement.

The design basis: how engineering will meet it

The design basis is the engineering team’s interpretation of the URS. It records the criteria, assumptions and standards each discipline will design to, and it is where a qualitative requirement becomes a quantified design parameter. For a pharmaceutical facility it usually includes:

• Room data sheets for every room: classification, pressure relationship, temperature, humidity, finishes, services and equipment.
• Design criteria for HVAC, water and utilities, electrical, fire, structure and automation.
• Applicable codes, standards and guidance, with their editions.
• Assumptions that still need confirmation, such as equipment data or local authority requirements, each with an owner and a due date.
• Design philosophies: zoning and flows, pressure cascade and airlocks, sanitization, redundancy and control.

The design basis should be reviewed and accepted by the owner, because it is where requirements are translated — and where they can be misunderstood. When a requirement cannot be met as written, the design basis is the place to record the deviation and its justification, not the drawings.

Design qualification: checking the design against the URS

Design qualification is the documented verification that the proposed design is suitable for its intended purpose. In practice it is a structured review of design documents — layouts, room data sheets, P&IDs, specifications and supplier proposals — against the URS, carried out at defined points in design rather than once at the end. Findings are recorded and closed, and the outcome is approved by the owner’s quality unit.

Traceability: the thread through the project

A traceability matrix links each requirement to where it is met in the design, to the DQ review that confirmed it, and later to the commissioning or qualification test that verifies it in the built facility. This has three practical benefits:

• Nothing important is lost between documents, contractors and stages.
• Tests are written for real requirements, so qualification does not repeat checks that add no value.
• When a change is proposed, the team can see immediately which requirements and tests it affects.

Facility URS and equipment URSs

Large projects rarely have one URS. The facility URS sets the overall requirements, and separate URSs are prepared for major systems and package equipment such as water generation, autoclaves, isolators, filling lines or building management and monitoring systems. These lower-level documents must be consistent with the facility URS and the design basis: the room that receives an isolator has to provide the services, space, classification and pressure relationships the isolator URS assumes.

Supplier responses to an equipment URS, often in the form of a functional or design specification, become part of the design reviewed in DQ. Factory and site acceptance tests can then be planned against the same requirement identifiers, so that supplier testing contributes to qualification instead of being repeated on site.

Common pitfalls

• A URS copied from another project, describing equipment or grades the new facility does not need.
• Requirements that prescribe a solution without a reason, closing off better options.
• Untestable statements that cannot be verified in DQ or qualification.
• A design basis that is never formally accepted, so assumptions are discovered during construction.
• DQ treated as a signature at the end of design rather than a series of reviews.

Key points

• The URS states what is needed; the design basis states how it will be met; DQ verifies the match.
• Write requirements that are unique, clear, verifiable and justified.
• Have the owner review and accept the design basis, including open assumptions.
• Maintain one traceability matrix from URS through DQ to test evidence.