Laboratory Incident Report

Incident Number: LAB-2025-012
Date of Incident: December 19, 2025
Product Name: Azithromycin (Finished Product)
Batch Number: 33334562222
Test: Related Substances (RS) by HPLC
Analyst Name: Anil Patel (ID: 5122)

I. Incident Description

During the HPLC analysis of Azithromycin Finished Product (Batch No: 33334562222), an Out-of-Trend (OOT) result was observed. The Standard Area was found to be 51,220, which is significantly higher than the theoretical value of 10,035. Because the system suitability criteria were not satisfied, the analytical sequence was aborted and an internal investigation was initiated.

II. Root Cause Analysis (RCA)

A comprehensive review of the analytical process was performed, and the following findings were documented:

Preparation Review: The volumetric measurements performed during standard preparation were audited.
Dilution Error: It was determined that the final dilution of the working standard was not executed.
Calculation Verification: The concentrated stock solution was found to have been injected instead of the final diluted preparation.
Conclusion: The root cause was identified as a non-compliance with the dilution steps specified in the Standard Test Procedure (STP).

III. Corrective and Preventive Actions (CAPA)

Corrective Actions:

The initial analytical data set was formally invalidated.
A fresh standard preparation was performed under the direct supervision of the Laboratory Supervisor.
The analysis was re-conducted, and a compliant standard area of 10,038 was obtained.
The batch was released only after the re-analysis results were verified and found to be within specifications.

Preventive Actions:

Training: Technical retraining on multi-stage dilution protocols was assigned to the analyst.
Documentation Update: The analytical worksheets were updated to require a “Dual-Sign-Off” for critical standard dilutions.
Instrument Control: A tighter “Area Check” limit has been programmed into the HPLC software to automatically flag deviations exceeding $20\%$ of the historical average.

IV. Final Conclusion

It was concluded that the high area response was caused by a human error during the dilution stage. No impact on the batch quality was identified, as the error was detected prior to sample quantification.