production, packaging, or warehouse departments for additional analytical testing in the QC lab of the API manufacturing unit.

3. Responsibilities

• QC Analyst: Receive retest samples, ensure correct labeling, and record in the Retest Sample Logbook.
• QC Coordinator: Assign sample numbers and manage retest sample storage.
• QA Officer: Review retest requests, approve testing plans, and verify final results.

4. Accountability

The Head of Quality Control is accountable for ensuring that all retest samples are handled per SOP, and that results are recorded and reported accurately.

5. Procedure

5.1 Definition of Retest Sample

1. A retest sample is a portion of the original or retained sample submitted again for testing due to:
   • Out-of-Specification (OOS) investigation
   • Out-of-Trend (OOT) observations
   • Verification of results
   • Stability monitoring
2. Retest must not be performed arbitrarily or without proper authorization.

5.2 Initiation of Retest Request

1. Submit the “Retest Sample Request Form” (Annexure-1) to QC.
2. The form must include:
   • Reason for retest
   • Batch number
   • Sample source (retain/sample)
   • Initial test results (if applicable)
3. QC Head must review and QA must authorize the request prior to retesting.

5.3 Receiving Retest Samples

1. Retest samples must be received in properly labeled and sealed containers.
2. Upon receipt, assign a unique retest sample ID using the format: RT/YY/XXX.
3. Enter details into the Retest Sample Receipt Log (Annexure-2).
4. Label retest samples using the Retest Sample Label (Annexure-3).

5.4 Retest Sample Label Format

• Label should include:
  • Retest Sample ID
  • Product name
  • Batch number
  • Date of receipt
  • Testing parameters
  • Authorized by
• Affix the label securely to each container using waterproof adhesive.

5.5 Storage of Retest Samples

1. Store retest samples under appropriate storage conditions as per product specification:
   • Ambient or Controlled Room Temperature
   • Refrigerated if required
2. Clearly segregate from routine and stability samples.
3. Retest samples must not be stored beyond their validity or retest period.

5.6 Analytical Testing and Documentation

1. Testing shall be performed only as per approved analytical method or test protocol.
2. Record test results in the analytical worksheet and attach retest request form.
3. Compare with initial test results and document all deviations.
4. Record the results in the Retest Sample Result Log (Annexure-4).

5.7 Reporting and Review

1. Submit completed test results to QA for review.
2. Include:
   • Raw data
   • Retest reason
   • Initial test results
   • Final conclusion
3. QA shall determine:
   • If the result is valid
   • If the batch can be released
   • If additional investigation is required

5.8 Handling of Invalid Retest Results

1. If results are inconsistent or outside specifications:
   • Initiate deviation or OOS investigation
   • Do not report results unless scientifically justified
   • Document all findings

5.9 Retention and Archival

1. All records must be retained for a minimum of 5 years or as per regulatory requirement.
2. Ensure physical samples are discarded after test or after expiry of retention period using Sample Disposal SOP.

6. Abbreviations

• QC: Quality Control
• QA: Quality Assurance
• OOS: Out of Specification
• OOT: Out of Trend
• RT: Retest

7. Documents

1. Retest Sample Request Form (Annexure-1)
2. Retest Sample Receipt Log (Annexure-2)
3. Retest Sample Label (Annexure-3)
4. Retest Sample Result Log (Annexure-4)
5. Deviation Form (if applicable)

8. References

• ICH Q2(R1) – Validation of Analytical Procedures
• 21 CFR Part 211 – Subpart I: Laboratory Controls
• WHO TRS No. 996 – Specifications for Pharmaceutical Preparations

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Retest Sample Request Form

Product	Batch No.	Retest Reason	Requested By	QA Approval
API-X	BCH2025X001	OOS Investigation	Rajesh Kumar	Sunita Reddy

Annexure-2: Retest Sample Receipt Log

Sample ID	Product	Batch No.	Date Received	Storage Condition
RT/25/005	API-X	BCH2025X001	14/04/2025	Ambient

Annexure-3: Retest Sample Label Format

Sample ID	Product	Batch No.	Date	Retest Parameter
RT/25/005	API-X	BCH2025X001	14/04/2025	Assay

Annexure-4: Retest Sample Result Log

Sample ID	Test Parameter	Result	Date of Testing	Analyst
RT/25/005	Assay	99.4%	15/04/2025	Priya Nair

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
01/01/2022	1.0	Initial SOP creation	New system implementation	QA Head
14/04/2025	2.0	Updated format and label control	Audit recommendation	QA Head