SOP: 100% Visual Inspection and AQL Re-Inspection of Injectable Products

This is a ready-to-use SOP. Replace every <<FILL: ...>> placeholder with your own specifics, look up the actual sampling values in ANSI/ASQ Z1.4 for your lot size and AQLs, and route the document through your normal document control. A worked filled specimen follows the template. It is an educational aid to adapt and verify, not a substitute for the compendial chapters and standards it references.

Document control header

1. Purpose

This procedure defines how every filled injectable unit is inspected for visible particulates and other defects, and how a statistically defined re-inspection sample confirms the inspection was effective. It implements the two distinct controls in USP General Chapter <790>: 100 percent inspection during manufacture and acceptance sampling on the inspected lot.

2. Scope

This procedure applies to all sterile injectable products in the container formats listed in the header, inspected manually, semi-automatically, or by automated visual inspection. It covers defect classification, segregation and reconciliation, the AQL re-inspection, and lot disposition input. Inspector qualification is governed by <<FILL: protocol/SOP-ID for inspector qualification>> and the defect library by <<FILL: document number of the defect library>>.

3. Responsibilities

4. Definitions

• 100% inspection: examination of every unit of the lot during manufacture, a process step, not a sampling test.
• AQL (Acceptance Quality Limit): the quality level that, for sampling purposes, is treated as an acceptable process average; a lower AQL is tighter.
• Critical, major, minor defect: severity classes defined in the defect library, each with its own AQL and disposition.
• Reconciliation: accounting for every unit of the lot (accepted, rejected, sampled, destroyed) so the numbers close.

5. Procedure

5.1 Prepare the inspection station

1. Set the black and white backgrounds and the illuminance to the qualified band for the product, and verify the illuminance at the actual inspection point with a calibrated meter. Use the higher band for difficult products such as amber containers, colored solutions, or suspensions.
2. Confirm the inspector (or the automated system) holds current qualified status for this product-and-container combination.
3. Confirm the current defect library and reference standards are at the station.

5.2 Perform 100% inspection

1. Inspect every unit against both backgrounds for the qualified viewing time, gently manipulating the unit to suspend particles without creating bubbles or foam.
2. Classify any defect found against the defect library and segregate rejects physically from accepted units.
3. Record accepted, rejected, and other-reason counts as the lot is inspected.
4. Do not increase throughput above the qualified rate; viewing time below the qualified time silently lowers detection.

5.3 Reconcile the lot

1. Account for every unit: accepted, rejected by defect class, pulled for other reasons, and destroyed.
2. Confirm the reconciliation closes to the lot quantity. A reconciliation that does not close is a deviation and a data-integrity and yield red flag; do not proceed until it is resolved.

5.4 Perform the AQL re-inspection

1. From the accepted units, determine the sample size: take the lot size and the General Inspection Level (Level II default unless a documented reason applies), find the sample-size code letter in Z1.4, and read the sample size.
2. Pull that sample at random from the accepted units.
3. Re-inspect the sample under qualified conditions by a qualified re-inspector who did not perform the original 100 percent inspection of that sample where practicable.
4. Count defectives by class and compare to the accept and reject numbers from Z1.4 for the AQL assigned to each class (tightest AQL for critical). Record the result per class.

5.5 Act on the AQL result

1. If every class passes, record the result and pass the lot to disposition.
2. If any class fails, especially critical, open a deviation. The lot is not released on the basis of the prior 100 percent inspection. Investigate why the inspection let those units through, decide on a 100 percent re-inspection or rejection per the investigation, and feed findings back into inspector or machine qualification.
3. Apply the defined normal, tightened, or reduced inspection state for the product based on its recent AQL history, per <<FILL: reference to the switching rule>>.

5.6 Document

1. Complete the lot inspection and AQL record (section 8) for every lot.
2. The inspector and re-inspector sign and date; QA reviews as part of disposition.

6. Acceptance criteria

• 100 percent of units were inspected under qualified conditions by a qualified inspector or system.
• Reconciliation closes to the lot quantity with every unit accounted for.
• The AQL sample was sized and drawn per Z1.4, and every defect class met its accept number.
• Any AQL failure was handled as a deviation with root-cause work, never a quiet re-release.
• The record is complete, signed, dated, and available for disposition.

7. References

USP General Chapter <790>, Visible Particulates in Injections (100% inspection and acceptance logic). USP General Chapter <1790>, Visual Inspection of Injections (inspection conditions, probability of detection). ANSI/ASQ Z1.4, Sampling Procedures and Tables for Inspection by Attributes (sample-size code letters, accept/reject numbers, switching rules); look up all sampling values there. 21 CFR 211.94 and 211.100/211.110 (containers/closures and in-process controls). EU GMP Annex 1 (2022), on individual inspection of filled parenteral containers and qualification of the inspection process.

Confirm the current version and clause numbers of each reference before issue.

8. Record generated: lot inspection and AQL record

9. Revision history

10. Approvals

Filled specimen

An illustrative lot, worked. The Z1.4 values are examples; read the real ones for your case.

The critical class had zero defectives against an accept number of one, so it passed; major and minor were within their accept numbers too. Reconciliation closed. Had the critical class exceeded its accept number, the lot would have gone to a deviation, not release, with root-cause work into why the 100 percent inspection let those units through.

Common inspection findings this SOP prevents

• Treating 100 percent inspection as if the AQL step were optional, or the reverse.
• An AQL failure quietly handled by re-inspect-and-pass without a deviation or root cause.
• Reconciliation that does not close, leaving units unaccounted for.
• Inspection performed above the qualified rate, dropping detection without anyone noticing.
• Sampling values worked from memory rather than read from Z1.4 for the actual lot size and AQLs.

How to adapt this SOP

1. Set your General Inspection Level, defect classes, and per-class AQLs, then read the sample sizes and accept/reject numbers from Z1.4 for each lot size band.
2. Reference your real inspector qualification, defect library, and switching-rule documents.
3. List your actual container formats in scope and qualify inspection per product-and-container combination.
4. Confirm every reference in section 7 against its current published version before issue.