OOS Investigation Explained: Phase 1 vs Phase 2 (21 CFR 211.192)

An out-of-specification result lands on your desk — and one wrong decision in the next hour can manufacture the evidence for your own warning letter. Marcus and Priya break down the two-phase OOS investigation step by step: Phase 1, the laboratory investigation, and Phase 2, the full-scale investigation, under 21 CFR 211.192 — from the Barr Labs decision to the retest rules to what to do on Monday morning. • Phase 1 vs Phase 2: what each phase covers and where the line is• The retest rules — when retesting is legitimate and when it's testing into compliance• Why "no assignable lab cause" is a finding, not a failure• What 21 CFR 211.192 actually requires, in plain language• The Monday-morning OOS playbook, in five steps New episodes every Monday and Wednesday — follow The GMP Insider so you never miss one.Connect with Tushar Arora on LinkedIn: https://www.linkedin.com/in/tushar-a-926382161Watch on YouTube: https://www.youtube.com/@TheGMPInsider Produced with AI assistance.