Invalidation of OOS Results and Retesting Samples Lack Scientific Rationale: USFDA form 483 to Torrent

There is a failure to thoroughly review any unexplained discrepancy and the failure of a batch or any of its components to meet any of its specifications whether or not the batch has been already distributed.

The observation cites 73% of Finished products Out of specifications (OOS) were invalidated (247 invalid OOS out of 340) during the period of Jan 2017 to March 2019. Observation also cites 61%  of stability OOS were invalidated (123 invalid OOS out of 203) during 2017-2019.

Firms’ investigation practices and procedure(s) are deficient. Several examples were found where original failing results were invalidated without scientifically sound and justifiable root cause, and results of passing re-test results were reported as the result of record.

Examples cited are:

A.    OOS/IN/F/FP/12/233, initiated on July 1, 2017. Tablet batch was OOS for assay. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation.  Initial OOS test results were invalidated based on reserve sample testing. The higher assay results were invalidated without identifying a definite root cause. The investigation could not conclusively identify if there is any laboratory error or manufacturing error and no CAPA was initiated.

B.    OOS/IN/F/FP/12/238, initiated on July 4, 2017. Tablet batch was OOS for assay. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation. Initial OOS test results were invalidated based on reserve sample testing. The higher assay results were invalidated without identifying a definite root cause. The investigation could not conclusively identify if there is any laboratory error or manufacturing error and no CAPA was initiated.

This observation was also cited in the Warning letter (MARCS-CMS585255 — dated October 08, 2019). The OOS was for Losartan Potassium and Hydrochlorothiazide (HCTZ) tablets batch number BP02D026 due to high HCTZ values. Despite no assignable root cause, initial high OOS results were invalidated and the batch was released based on retested reserve sample results and batch distributed to US market. The Warning letter also mentions multiple OOS investigations related to assay, dissolution were closed without assignable root cause, or lacked adequate scientific justification for root cause & despite inadequate OOS investigations, firm disregarded initial failing OOS results and released batches based on retest results. 

C. OOS/IN/F/FP/18/070. Same deficient investigation process as in (A) and (B) was followed to probe assay failure for tablets batch. No definitive root cause was identified. 

D. OOS/IB/F/FP/17/340 initiated on November 6, 2017.Capsules batch (Process Validation Batch) OOS for assay failure. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation. Initial OOS test results were invalidated based on reserve sample testing. 

The process validation report PVR/CD.74.01-2E/17/01-01 approved on December 27, 2017 stated – “no specific root cause identified at manufacturing stage for out of specification result observed. As per manufacturing investigation report, the OOS result obtained in the subject batch might be due to sample preparation error i.e analytical variation which was not established during the investigation”.  The impact if any of higher sample weights yielding low assay results was not evaluated in the investigation report. Additionally, the validation batch was manufactured to support the qualification of an alternate API supplier for the product. This alternate API was subsequently deemed qualified and (several) lots of finished product shipped to US market have used this API. 

E. OOS/IN/F/FP/18/103. Same deficient investigation process as in (D) was utilised to probe failure for another Capsule batch. No definitive root cause was identified. 

F. OOS/IN/F/ST/18/354, initiated on October 11, 2018. Failing assay result for tablets during stability [3M(250C/60%RH]. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation. The initial OOS results were invalidated based on passing results from triplicate analysis. The investigation report states that the initial failures occurred due to sample preparation error i.e some powder loss while transferring to the volumetric flask. This presumptive cause is not scientifically proven nor substantiated in the investigation report. This batch was released to US distribution. The batch is an annual stability batch that represents (several) batches released to US market. 

G. OOS/IN/F/FP/17/309, initiated on September 29, 2017. Dissolution failure. No root cause was identified in Phase 1 or Phase II investigations.

• • S1 results (6 units) – Average 88 [Acceptance Criteria (S1): Each unit NLT Q+5%] 
  • S2 results (next 6 units) – Average 77 [Criteria (S2): Average of 12 units is > Q; and no
    unit is less than Q-15%]
  • Additional Set 1, Set II – Average 86 [Criteria (S3): Average of 24 units is > Q; NMT 2
    unit is less than Q-15%; No unit is less than Q-25%]
  • Additional Set III & Average of Set 1, II and III – Average 92

Firm failed to follow the USP dissolution criteria for reporting results. Instead of reporting average of first 24 units, the firm deficiently reported the average results of additional 18 units (from Set 1, II and III) and ignored the initial S1 and S2 results from reporting. In summary

Reported results: Average 92% (from retested 18 units) 

Ignored results: Average 86% (From S1 and S2)

This deficient practice resulted in the minimum dissolution value (from S1 and S2) from not being reported in the Certificate of Analysis. In addition the firms written procedure GTP/USP/022 titled, “Dissolution” was not followed during reporting of results. 

H OOS/IN/F/ST/17/364, initiated on September 20, 2017. Dissolution failure of tablet–3 at the10 hour time point against specification limit- stability, 2-month sample (400C/75% RH) blister packing. No laboratory error was identified during investigation. However the initial results were invalidated without a valid assignable root cause and the results from reanalysis (n=18 units) was reported as the result of record. This was a Bio batch in support of ANDA filing. 

I. OOS/IN/F/FP/17/295, initiated on September 15, 2017.Dissolution failure of tablet-1 at the 6th hour time point, 12th hour time point, 24th hour time point. Root cause was assigned to lower length of sinker used for dissolution test. However, the actual length of sinker used was not recorded in the investigation report. Initial results were invalidated and results from reanalysis reported as the result of record. This was an exhibit batch in support of ANDA filing.

J. OOS/IN/F/ST/18/135 initiated on May 02, 2018. Dissolution failure. No laboratory error was identified from extensive hypothesis testing. However firm still assigned the root cause as suspected laboratory error and invalidated the original OOS results.

Firm failed to follow the USP dissolution criteria for reporting of results. The firm invalidated the original results without a scientifically sound root cause. The dissolution results would have failed specification limits if the first set of 6 units were considerd for reporting. In addition the firms written procedure GTP/USP/022 titled, “Dissolution” was not followed during reporting of results

There is a failure to thoroughly review any unexplained discrepancy and the failure of a batch or any of its components to meet any of its specifications whether or not the batch has been already distributed.

The observation cites 73% of Finished products Out of specifications (OOS) were invalidated (247 invalid OOS out of 340) during the period of Jan 2017 to March 2019. Observation also cites 61%  of stability OOS were invalidated (123 invalid OOS out of 203) during 2017-2019.

Firms’ investigation practices and procedure(s) are deficient. Several examples were found where original failing results were invalidated without scientifically sound and justifiable root cause, and results of passing re-test results were reported as the result of record.

Examples cited are:

A.    OOS/IN/F/FP/12/233, initiated on July 1, 2017. Tablet batch was OOS for assay. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation.  Initial OOS test results were invalidated based on reserve sample testing. The higher assay results were invalidated without identifying a definite root cause. The investigation could not conclusively identify if there is any laboratory error or manufacturing error and no CAPA was initiated.

B.    OOS/IN/F/FP/12/238, initiated on July 4, 2017. Tablet batch was OOS for assay. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation. Initial OOS test results were invalidated based on reserve sample testing. The higher assay results were invalidated without identifying a definite root cause. The investigation could not conclusively identify if there is any laboratory error or manufacturing error and no CAPA was initiated.

This observation was also cited in the Warning letter (MARCS-CMS585255 — dated October 08, 2019). The OOS was for Losartan Potassium and Hydrochlorothiazide (HCTZ) tablets batch number BP02D026 due to high HCTZ values. Despite no assignable root cause, initial high OOS results were invalidated and the batch was released based on retested reserve sample results and batch distributed to US market. The Warning letter also mentions multiple OOS investigations related to assay, dissolution were closed without assignable root cause, or lacked adequate scientific justification for root cause & despite inadequate OOS investigations, firm disregarded initial failing OOS results and released batches based on retest results. 

C. OOS/IN/F/FP/18/070. Same deficient investigation process as in (A) and (B) was followed to probe assay failure for tablets batch. No definitive root cause was identified. 

D. OOS/IB/F/FP/17/340 initiated on November 6, 2017.Capsules batch (Process Validation Batch) OOS for assay failure. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation. Initial OOS test results were invalidated based on reserve sample testing. 

The process validation report PVR/CD.74.01-2E/17/01-01 approved on December 27, 2017 stated – “no specific root cause identified at manufacturing stage for out of specification result observed. As per manufacturing investigation report, the OOS result obtained in the subject batch might be due to sample preparation error i.e analytical variation which was not established during the investigation”.  The impact if any of higher sample weights yielding low assay results was not evaluated in the investigation report. Additionally, the validation batch was manufactured to support the qualification of an alternate API supplier for the product. This alternate API was subsequently deemed qualified and (several) lots of finished product shipped to US market have used this API. 

E. OOS/IN/F/FP/18/103. Same deficient investigation process as in (D) was utilised to probe failure for another Capsule batch. No definitive root cause was identified. 

F. OOS/IN/F/ST/18/354, initiated on October 11, 2018. Failing assay result for tablets during stability [3M(250C/60%RH]. OOS results were confirmed during preliminary investigation and hypothesis testing (Phase 1) with no identified root cause. No manufacturing error was identified during Phase II investigation. The initial OOS results were invalidated based on passing results from triplicate analysis. The investigation report states that the initial failures occurred due to sample preparation error i.e some powder loss while transferring to the volumetric flask. This presumptive cause is not scientifically proven nor substantiated in the investigation report. This batch was released to US distribution. The batch is an annual stability batch that represents (several) batches released to US market. 

G. OOS/IN/F/FP/17/309, initiated on September 29, 2017. Dissolution failure. No root cause was identified in Phase 1 or Phase II investigations.

• • S1 results (6 units) – Average 88 [Acceptance Criteria (S1): Each unit NLT Q+5%] 
  • S2 results (next 6 units) – Average 77 [Criteria (S2): Average of 12 units is > Q; and no
    unit is less than Q-15%]
  • Additional Set 1, Set II – Average 86 [Criteria (S3): Average of 24 units is > Q; NMT 2
    unit is less than Q-15%; No unit is less than Q-25%]
  • Additional Set III & Average of Set 1, II and III – Average 92

Firm failed to follow the USP dissolution criteria for reporting results. Instead of reporting average of first 24 units, the firm deficiently reported the average results of additional 18 units (from Set 1, II and III) and ignored the initial S1 and S2 results from reporting. In summary

Reported results: Average 92% (from retested 18 units) 

Ignored results: Average 86% (From S1 and S2)

This deficient practice resulted in the minimum dissolution value (from S1 and S2) from not being reported in the Certificate of Analysis. In addition the firms written procedure GTP/USP/022 titled, “Dissolution” was not followed during reporting of results. 

H OOS/IN/F/ST/17/364, initiated on September 20, 2017. Dissolution failure of tablet–3 at the10 hour time point against specification limit- stability, 2-month sample (400C/75% RH) blister packing. No laboratory error was identified during investigation. However the initial results were invalidated without a valid assignable root cause and the results from reanalysis (n=18 units) was reported as the result of record. This was a Bio batch in support of ANDA filing. 

I. OOS/IN/F/FP/17/295, initiated on September 15, 2017.Dissolution failure of tablet-1 at the 6th hour time point, 12th hour time point, 24th hour time point. Root cause was assigned to lower length of sinker used for dissolution test. However, the actual length of sinker used was not recorded in the investigation report. Initial results were invalidated and results from reanalysis reported as the result of record. This was an exhibit batch in support of ANDA filing.

J. OOS/IN/F/ST/18/135 initiated on May 02, 2018. Dissolution failure. No laboratory error was identified from extensive hypothesis testing. However firm still assigned the root cause as suspected laboratory error and invalidated the original OOS results.

Firm failed to follow the USP dissolution criteria for reporting of results. The firm invalidated the original results without a scientifically sound root cause. The dissolution results would have failed specification limits if the first set of 6 units were considerd for reporting. In addition the firms written procedure GTP/USP/022 titled, “Dissolution” was not followed during reporting of results

OOS procedure and investigation practices should be logical and should follow a defined flow and scientifically sound. If during Phase 1A investigation no obvious laboratory error is identified, Phase 1B should look at all other possible factors – analyst error, instrument error, method error, sample preparation and handling error, sample error, standards, calibrations, method validation related errors (consistency, precision, robustness of method), contamination, glassware error, analyst understanding of test and procedure (interview the analyst), other interferences due to various factors (e.g. lab environment). The checklist can be as elaborate as possible. (Refer the MHRA guideline for OOS investigations).  This investigation should be performed by the analyst and supervisor together, and can even look at aspects beyond the checklist. From this evaluation arrive at any obvious causes or potential causes. These potential causes from Phase 1B investigation form the basis for hypothesis testing. And as elaborated in the MHRA guideline, multiple hypothesis can be explored. But the important point is that the hypothesis testing plan should be defined covering all different hypothesis that the Quality unit / QC want to explore, documented and signed off. Now hypothesis testing(s) can be taken up as per plan; however if the hypothesis testing activity also returns OOS result and the hypothesis invalid, further testing’s should stop. It will be a wrong practice to develop a second hypothesis plan to again test the samples – then it becomes testing into compliance. Many times what happen is that the Phase 1B investigation is hurried through, and the checklist filled in showing that there was no possible errors – e.g analyst are trained well, no sample preparation error or weighing error, method is perfect, instruments were in perfect condition and so on; And minimal hypothesis testing plan will be proposed – e.g filtration, re-dilution etc. Most often these hypothesis test results will still be OOS. Now the firm has lost the opportunity for exploring further possible laboratory error, say sample contamination, sample weighment, method robustness. If now firm develop a second hypothesis to explore these factors, it becomes suspicious – as in the first place firm would have concluded that all aspects of laboratory error were found to be in order. (Note the wordings of the FDA observation: OOS results were confirmed during preliminary investigation and hypothesis testing …. Initial OOS test results were invalidated based on reserve sample testing). Many times, when OOS are invalidated for suspected laboratory error,  clear root causes are not identified, Evidences to support root causes are not provided, clear CAPAs are not identified for preventing such errors in future. This raises doubts about whether the assignment of laboratory error as reason for OOS is justified. Another important point to note is OOS in Dissolution tests. By design this is a 3 stage tests. So the investigations and resolution of the OOS should also address the three stages. Organisations should have a comprehensive approach to investigating OOS:

1. OOS procedure should clearly define the flow for OOS investigations.

a. Phase 1A (Obvious error), Phase 1B laboratory investigation for potential causes by analyst and supervisor. Collect all evidences of possible errors being identified – e.g – photographs, other documents and annex to the investigation report. 

b. Hypothesis plan covering all possible factors. Document and sign of the hypothesis plan. Perform preliminary hypothesis tests using same sample preparations – filtration error, dilution error etc. If root cause(s) are not identified, proceed for Phase II -Detailed investigation.

c. Phase II detailed investigation to cover:

i. Manufacturing investigation. Investigate possibilities of production process issues to cause OOS. If root cause is identified, conclude the OOS. Proceed with further disposition actions.

ii. If manufacturing investigation do not identify any root cause, review need for further laboratory investigation. Here additional hypothesis testing shall be considered with additional portions of original sample (Based on the hypothesis plan – for e.g – sample weighing error, sample contamination, sample deterioration and so on). Extremely rarely resampling may also need to be considered. It is important to note that the hypothesis testing being performed during Phase II is not contradicting the Phase 1B investigation checklist findings. Hence it is critical to ensure that the Phase IB investigation is performed with full attention to details and identify all possible factors that may need to be tested further during Phase II investigation.

iii. If Phase II laboratory investigation and hypothesis testing again results in OOS results, no further retesting of reserve samples is justified. OOS will need to be treated as valid. If hypothesis testing shows laboratory error could be a reason for OOS, this has to be concluded by a Retest. The hypothesis tests are performed ideally by a second equally competent analyst.

d. Retest with original portion of the sample (unless sample contamination /deterioration is a possible cause or sufficient quantity of sample is not available for retest). Retest may be performed by original analyst or second analyst. The retest plan should be defined and documented before initiating retest, and shall cover at least the same number of tests as called for in the test procedure (e.g – if assay has to be performed in duplicate in original test procedure, retest should also perform the test in duplicate). It is even desirable to perform retest analysis in more replicates (e.g – perform in triplicate) as it lends statistical significance. If the test results of Retest is also complying the initial OOS results may be invalidated; if not the OOS shall be concluded as valid. (Unless there are extreme, obvious issues happened during a retest such as an instrument malfunction or sample spillage due to which the retest results need to be rejected).

2. In the case of stability analysis also same process as detailed above applies. Retest shall be considered only after scientifically sound hypothesis testing. And if the firm invalidates the initial OOS results after hypothesis testing and retest, firms should also keep track of the results during further stability timepoints and make addendums to the original OOS investigation report. Firms can make a commitment to do the same in the original OOS report;

3. In the case of OOS results in dissolution also same rules apply. When in the S1 (or S2 testing) there are unit values which are very low (or different) compared to other values and average value, this should be investigated. It is not acceptable to invalidate the OOS after performing S2 and S3 stages (where no abnormality was observed) plus additional 6 / 12 units testing, as the test by design has 3 stages. The additional tests should be based on hypothesis testing plan, and hypothesis testing (investigation testing) results cannot be the basis for invalidating the initial OOS results (MHRA guideline). Full retest shall be performed if hypothesis testing (additional testing) indicates the initial OOS result may be due to laboratory error. The retest shall cover the S1, S2, S3 stages (if the Retest results of S1 stage warrants going to S2 stage; and further S3 stage). The initial OOS results (S1, S2, S3) shall be firmly invalidated with sound rationale and results of the Retest shall be reported as the result of record.

4. It is not enough to have only the procedure (SOP) documented describing the philosophy and steps of OOS investigation. The laboratory (QC) team as well as Quality unit should be properly trained and coached in the practice of OOS investigation to ensure the practice is firmly established. Process flow checklist should be established for evaluating whether the investigation flow is logical and scientific. One of the actions firms’ can consider is to conduct an OOS review sessions every month involving the technical team members (QA, QC, Production and other functions) to see whether the OOS flow is logically followed for each OOS.

1. Review all invalid OOS investigations to assess whether the laboratory error / root cause is conclusively established. Engage expert cGMP consultant for the review along with firms’ team to make sure the review is comprehensive and unbiased. The scope of evaluation shall cover all batches within expiry (distributed and in inventory). Where the hypothesis testing / retesting lack sound rationale, acknowledge the shortcomings in initial laboratory investigation (Phase 1A, Phase 1B), reevaluate the OOS for laboratory error (with Phase 1A, IB checklists) and identify potential errors (with sound rationale). If the laboratory errors are conclusively established, identify the root causes and establish appropriate CAPAs.

a. For example CAPA for error during sample transfer may include a checkpoint in analysis review checklists, monitoring of the sample preparation step by supervisor/ peers, stagewise clearance of analysis (e.g-sample preparation, mobile phase preparation, chromatography,..). If there is reason to suspect that the sample preparation is not appropriate, record the same, do not proceed with analysis; Initiate fresh analysis. CAPA for dissolution test OOS may include recording the sinker height in analytical test sheet, keep different type of sinkers segregated to avoid mix up and so on.

2. If the laboratory error could not be conclusively established, initiate manufacturing investigation to identify potential causes. Based on this if potential causes are identified and OOS is considered valid, take up remediation actions (e.g. – Product recall). In such cases an impact assessment for impact of other batches of the product being similarly affected shall also be performed. 

3. If no laboratory error or manufacturing process concerns could be established, Perform risk assessment for such OOS – assess previous history of the product /process, factors that can cause such OOS and probability of occurrence. If a risk of OOS exist take remedial actions. If the assessment concludes minimal / no risk document the same with strong scientific rationale. 

4. Enhance the OOS procedure with detailed investigation flow chart. Train and coach personnel on investigations. Perform monthly review of OOS investigations by a cross functional team involving Quality, Production and other technical functions, to assess the logical flow and scientific rationale of investigations and conclusions. Review the OOS, conclusions, CAPAs in periodic Management review meetings, involving senior / executive management.