What are the Checkpoints of OOS investigation?

What are the Checkpoints Of OOS Investigation?

A laboratory test, which is required by CGMP regulations (§§211.160 and 211.165), is required to ensure that components, containers and closures, in-process materials, and finished products meet specifications, including stability testing specifications.

There is FDA oos guidance, “Guidance for industry Investigating Out-of Specification (OOS) Test Results for Pharmaceutical Production

The FDA requires that an investigation be conducted as per 21 CFR Production Record Review (§§ 211.192) if an OOS test result is obtained.

As per USFDA to confirm the OOS root cause need to investigate the OOS thoroughly, unbiased, and with sound scientific justification.

To meet the regulatory requirement and thorough investigation certain checkpoints should be verified. The checkpoints should be from Laboratory Investigation, manufacturing investigation and warehouse investigation.

First, need to understand what is OOS in pharmaceuticals?

What is out-of-specification (OOS)?

A result that is out of specification (OOS) is one that does not conform or meet the predetermined limit or acceptance criteria set by the manufacturer or laboratory.

Checkpoints Of OOS Investigation:

Checkpoints of OOS investigation are divided into three parts Laboratory investigation checkpoints, Manufacturing investigation checkpoints, and warehouse investigation checkpoints.

Laboratory Investigation Checkpoints:

Laboratory investigation checkpoints include:

  • Analyst errors
  • Instrument/Equipment errors
  • Laboratory System errors

Let’s understand the checklist of oos investigation in depth.

Analyst Errors:

  1. Weighing and measurement errors (sample weight & measurement
  2. Calculation errors (and raw data completeness)
  3. Analytical errors related to dilutions, mobile phases, filters, chromatography, conditions, and so forth.
  4. Analyze the critical steps that were followed during analysis
  5. The reference/working standard used in the analysis is correct
  6. Assay value and storage condition are determined correctly for the reference/working standard
  7. Check the appearance, potency, expiry date, and LOD/water is mentioned.
  8. Whether the test solution(s) are properly prepared
  9. During preparation, any loss of standard solution or test solution
  10. Other analytical techniques were not properly applied during the test
  11. If any unusual or unexpected effect is observed for standard or test preparation (e.g. If equipment is contaminated by a previous sample)
  12. Whether any alternate validated method is used for the analysis
  13. If the analyst is qualified
  14. Is the analyst trained to carry out the test
  15. Whether the environmental conditions are suitable for the test
  16. Cleaning of glassware and calibration status
  17. Analyst Qualification

Instrument/Equipment Errors:

  1. Analytical equipment (including glassware) that didn’t work or was not calibrated was used in the analysis.
  2. Verify if the system meets the requirements for RSD, resolution factor, and l or other criteria.
  3. Ensure that the chromatographic analysis does not include any out-of-limit parameters.
  4. Column used is correct
  5. This column has been used previously
  6. Instrument/equipment calibration status
  7. Instrument/Equipment preventive maintenance

Laboratory System Errors:

  1. Confirm that the analyst understands the test method; discuss the test method with the analyst.
  2. A trained analyst should be familiar with the instrument/ equipment and maintain the records
  3. Schedule of calibrations
  4. Solutions’ shelf life
  5. Calibration procedure and test method
  6. Working standard qualification
  7. Efficiency of columns
  8. Environmental conditions

Manufacturing Investigation checkpoints:

Manufacturing investigation checkpoints include:

  1. Equipment errors
  2. Operator errors
  3. Production system errors

Equipment Errors:

  1. Is the equipment specified and validated?
  2. Is there any malfunctioning of the equipment?
  3. Are there any power outages for extended periods during manufacturing?

Operators Errors:

  1. Does operators trained on the equipment
  2. Did the operator make any errors (wrong weight, wrong material, incorrect sequence of additions)?
  3. Interview with the operator

Production System Errors:

  1. Are there any deviations from cGMP/SOP?
  2. Is the process validated?
  3. Does the specified environmental condition apply?
  4. Is the standard Master Formula followed?
  5. Are correct sampling procedures followed?
  6. Do batch production records have the correct entries and standard manufacturing procedure is followed?
  7. Is there a change in the blend time or dry time?
  8. During processing, was there any spillage of material?
  9. Does the environment meet the specified conditions?
  10. Are all steps of the manufacturing process carried out within the approved timeframe?
  11. The manufacturing process aspects that may be responsible for the problem are listed here.
  12. When storage containers are at different stages of manufacturing, whether they are stored appropriately in designated locations.
  13. Describe how long the containers are stored at various stages.
  14. Are yields in the previous and next batch within acceptable limits?
  15. Make sure the yield is reconciled at each stage. In case the yield exceeds the standard, explain why.
  16. Does documentation of the process is reviewed.
  17. If you have any other observations, record them.

Warehouse Investigation checkpoints:

  1. Did the material come from an approved vendor?
  2. Do RM/PM stores maintain their storage conditions?
  3. Does the dispensing operators are trained?
  4. Are the materials used as described in the bill of materials?
  5. Do physical stock and written quantity match for used material?
  6. Have previous and next batches been dispensed with proper line-clearance procedures?
  7. Are the materials dispensed within the validated time before manufacturing begins?

If these checkpoints of OOS Investigation are followed, there are high chances of getting the root cause of OOS.


OOS investigation is a lengthy and time-consuming activity as compared to routine incident investigation. To make it easy if we prepare and follow checkpoints of oos investigation, it will help to save time as well as to find the root cause of oos.

checkpoints of oos investigation

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