What an OQ Protocol Typically Includes

• Scope and acceptance criteria: what will be tested and how pass/fail is defined
• Prerequisites: completed IQ, calibration status, SOP availability, training, utilities readiness
• Functional tests: start/stop, modes, sequences, cycle steps, basic operation
• Operating ranges: verification of min/nominal/max setpoints and control stability
• Alarm tests: alarm generation, display, acknowledgement, and response requirements
• Interlock challenge tests: forced fault conditions to prove the system prevents unsafe/quality-risk actions
• Sensor verification: indicators, transmitters, probes, load cells (as applicable)
• Software/controls checks: recipe parameters, user roles, audit trail, backups (if applicable)
• Data recording: printouts/logs, electronic records, time stamps, traceability
• Deviations: documentation, impact assessment, corrective actions, retest logic
• Conclusion: readiness statement for PQ/production use

Mini Example: Typical OQ Tests for an Autoclave

An autoclave OQ commonly includes:

• Cycle parameter verification (temperature, pressure, time setpoints)
• Alarm challenge: high temperature, low temperature, door interlock, vacuum failure
• Interlock verification: cycle cannot start if door not locked; door cannot open during cycle
• Chart/record review: data capture integrity, audit trail (if electronic), batch record printouts
• Worst-case controls testing: upper and lower operating limits within validated ranges

Worst-Case Testing (What Regulators Expect You to Explain)

OQ often includes worst-case or challenge conditions to show the system can control variability. “Worst-case” doesn’t mean unsafe or damaging—it means testing at the edges of approved operating ranges to demonstrate control and detection. A strong justification explains:

• Why these limits are selected (risk-based)
• Which quality attributes are protected by these controls
• How the system responds to excursions (alarms/interlocks)

Common Confusions (Avoid These Audit Traps)

• OQ = running product: Not exactly. PQ is where performance is demonstrated in routine use. OQ is controlled functional/range testing.
• Skipping alarm/interlock challenges: Auditors frequently ask for alarm/interlock evidence because this is “control strategy in action.”
• No acceptance criteria: “It looked OK” is not acceptable. Define objective pass/fail criteria.
• Weak prerequisites: If calibration isn’t current or SOPs aren’t ready, OQ data credibility drops.

Audit-Ready Talking Points

• Show how you selected operating ranges and why they matter for quality
• Explain your alarm/interlock testing philosophy and evidence of challenge tests
• Demonstrate data integrity controls for electronic records (where applicable)
• Show how deviations were assessed and what retesting logic was applied

Quick OQ Checklist (Practical)

• IQ is complete and approved
• Critical instruments are calibrated and within due date
• Acceptance criteria are objective and documented
• Operating ranges include edge-of-range checks (risk-based)
• Alarm and interlock challenge tests are performed and evidenced
• Data capture (paper/electronic) is traceable and reviewable
• All deviations are documented, assessed, corrected, and closed

FAQs

What is OQ used for in pharma?

OQ verifies that a system operates correctly across defined ranges and that controls, alarms, and interlocks function to protect product quality.

Is worst-case testing mandatory in OQ?

Regulators expect challenge testing where it is risk-justified. You should be able to defend why your OQ tests provide confidence across operating ranges.

Can we start PQ if some OQ tests fail?

No. OQ failures should be investigated, corrected, and retested. Proceeding to PQ with unresolved OQ issues weakens validation conclusions and invites audit findings.

What is the difference between OQ and PQ data?

OQ data focuses on functional/range verification and control behavior. PQ data demonstrates consistent performance during routine operation using defined loads or real process conditions.

What do inspectors commonly ask during OQ review?

They often ask to see alarm/interlock challenge evidence, acceptance criteria, calibration status, deviation handling, and the rationale for tested ranges.