How Does the Squeglia Plan Work in CCI

Once a CCI positive result is confirmed — instrument challenge passed, classification assigned, retest completed where applicable — the question shifts from the individual unit to the batch. The Squeglia Zero Acceptance Number sampling plan is the statistical tool that answers the lot-level question: given that one defect has been found, what does the broader population tell us about batch quality?

What is the Squeglia plan and why is it used for CCI?

The Squeglia c=0 plan is a published attribute sampling framework that specifies sample sizes for attribute inspection at defined confidence levels, with an acceptance number of zero. PTI recommends it because it is well-established in pharmaceutical QA practice, regulatorily defensible, and directly suited to the high-stakes nature of sterile injectable CCI. Any additional defect found in the recovery sample immediately triggers escalation — there is no intermediate step.

What are the default parameters?

The PTI framework applies a 95% confidence level and a post-positive recovery AQL of 1-in-1,000 (0.1%), achieved with approximately 300 units tested at c=0. This is an honest statement of what the plan demonstrates. Achieving a demonstrated AQL of 1-in-10,000 at 95% confidence would require approximately 30,000 units — equivalent to 100% inspection for most batch sizes. The 300-unit Squeglia plan functions as a scientifically defensible lot sentinel within a layered quality system where process validation has already established the baseline quality level.

What population is sampled?

The at-risk population is the narrowest defensible subgroup that traceability supports: filler head, crimper station, time window, nest or tray position, operator assignment, or stopper lot. If no traceability record can narrow the suspect population below the full lot, the entire lot becomes the escalation boundary. Units already tested and documented as passing during the primary sampling run may credit toward the required Squeglia n, reducing the number of additional units to be pulled.

What happens if the Squeglia sample finds an additional defect?

The plan escalates immediately to 100% CCI inspection of the at-risk population. There is no intermediate step and no relaxed acceptance criterion. Squeglia is a sentinel tool — if it finds a second defect, it has answered its question: the lot has a quality problem that only exhaustive inspection can characterize.

Can a clean Squeglia sample alone release the lot?

No. Release requires two independent conditions: zero additional defects in the recovery sample, and a documented root cause for the original positive. A clean sample without a root cause conclusion means the investigation is incomplete. The batch remains on hold until root cause is established or the lot is rejected.