Risk Based Inspection (RBI) – Schedule M Point 4.16 focuses on one core question in sterile manufacturing: Is Water for Injection (WFI) actually being used where Schedule M expects it, and is the use controlled and documented? In the CDSCO RBI checklist/benchmarks, Point 4.16 asks inspectors to specify whether WFI is used for: (1) bulk preparations of liquid injections, (2) final rinse of product containers for sterile preparations, (3) final rinse of machine parts for sterile preparations, and (4) preparation of disinfectant solutions for use in critical areas (sterile preparations). CDSCO
Why this point is “risk-based”
These four applications directly affect sterility assurance and patient safety. If PW (or poorly controlled water) is mistakenly used, the risk increases for microbial/pyrogen contamination, chemical contamination, and loss of control in aseptic areas.
What inspectors typically verify under 4.16
- System and usage mapping: A clear diagram/description showing which outlets are WFI and where each is used (compounding, component rinse, parts rinse, disinfectant prep). CDSCO
- SOPs and records: Written procedures for each activity (bulk prep, rinsing, disinfectant prep) and executed records proving WFI use batch-to-batch (logbooks, batch records, rinse records). CDSCO
- Physical checks on shopfloor: Correct labeling of points-of-use, segregation to prevent mix-up (PW vs WFI), and operator practices that match SOPs.
- Link to WFI quality controls: Evidence that WFI meets required standards and is routinely monitored, since “used” is meaningless unless quality is controlled (often checked alongside 4.15 in the same section). CDSCO
- Critical-area disinfectant preparation controls: Confirm disinfectants for sterile critical areas are prepared with WFI, correctly labeled, within hold time, and traceable to preparation records. CDSCO
Overall, passing 4.16 means the site demonstrates correct WFI application + strong prevention of mix-ups + complete documentation, consistent with Schedule M’s GMP expectations used in RBI.