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Fiona McGuinness

Investigating Out of Specification Results

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Introduction

g What do we mean by OOS, OOT, atypical or unexpected results?

g Documented procedureg Investigationg What happens when you can’t find the cause?g Examplesg Questions

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What do we mean…?

g Out of Specification (OOS)n Result that does not comply with stated accepted criteria

g Out of trend (OOT)n A stability result that does not follow the trend of other

stability results during a stability studyn A result that does not follow the trend based on data

already collected with the same compoundg Atypical

n May be within specification but unexpected or questionableg All unexpected results!

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Documented Procedure

g Important that all laboratories have a fully documented OOS investigation proceduren Clearly state what the investigation will be based

on, what you will do in each case, actions and outcomes from the investigation

n Clients and regulatory agencies like to see a procedure and that it is being followed!

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Initial Investigation

g First step is to QC Check the data generated to ensure that no identifiable calculation or preparation errors have been made

g Investigate the analysis….n Calibration standards, extraction volumes, dilution

steps etcn Instrument set-up, injection volumes, mobile

phases, diluents, instrument working…

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Re-dilution

g An investigative runn Has a dilution error been made?

g What if dilution results are different?g Don’t cherry pick results!

n Confirm results by a 3rd dilution!

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Preparation of the Formulation

g Check the request, method, weights of test substance and vehicle as appropriate.

g Check calculations

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Contingency Analysis

g No obvious analytical error (including dilutions), no obvious preparation error…

n Perform analysis of contingency samples

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What happens when we can’t find the cause of an unexpected result?

g Meetingg Root Cause Analysis investigationg Corrective and Preventative Actionsg Analysis of next formulated occasiong Discussion and agreement with senior members

of department and SD

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Fishbone

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5 Whys

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Example 1

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Week of Formulation

Group NominalAnalysed

concentration (mg/ml)   RME% Difference from

Mean

  inclusion Analysis 1 Analysis 2 Mean (%) Analysis 1 Analysis 2

  (mg/ml)            

13 1 0 ND ND - - -2 0.75 2.6904 2.734 2.71 261.3 -0.80 0.803 1.5 1.4978 1.5041 1.50 0.0 -0.21 0.214 2.75 0.61669 0.60652 0.61 -77.7 0.83 -0.83

• Group 2 samples are above the quantification range

• Group 4 samples are below the quantification range

• Obvious error?

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Investigation

g Samples had been booked into the department in the wrong order

g Analyst followed the booking in rather than looking at the labels of the samples

g New samples were taken from the bulk sample provided by Pharmacy

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Re-sampled Analysis

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Week of Formulation

Group NominalAnalysed

concentration (mg/ml)   RME% Difference from

Mean  inclusion Analysis 1 Analysis 2 Mean (%) Analysis 1 Analysis 2  (mg/ml)            

13 1 0 ND ND - - -2 0.75 0.72346 0.71577 0.720 -4.0 0.53 -0.533 1.5 1.4978 1.5041 1.50 0.0 -0.21 0.214 2.75 2.7186 2.5703 2.64 -4.0 2.80 -2.80

• All samples now within specification• Original results for Groups 2 and 4 not

reported due to an identified analyst error

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Example 2

Week of Formulation

Group NominalAnalysed concentration

(mg/ml)   RME% Difference from

Mean  inclusion Analysis 1 Analysis 2 Mean (%) Analysis 1Analysis 2

  (mg/ml)            

1 1 0 ND ND - - -2 10 9.6428 8.1326 8.89 -11.1 8.50 -8.503 30 27.686 26.675 27.2 -9.3 1.86 -1.864 60 58.827 57.72 58.3 -2.8 0.95 -0.95

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• Investigation shows no calculation errors• Re-dilution confirms the results• No preparation errors found with formulation

preparation

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Contingency Analysis

Week of Formulation

Group NominalAnalysed concentration

(mg/ml)   RME Precision% Difference from

Mean

  inclusion Analysis 1 Analysis 2 Mean (%)from mean

Analysis 1

Analysis 2

  (mg/ml)         (%)    

1 2 cont 10 9.9601 10.022 9.99 -0.1 0.44 -0.31 0.31

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• Contingency analysis showed that results were acceptable

• What should we do about the original analysis?

• Outlier test?

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Outlier Test – Dixon’s Q Test

n 3 4 5 6 7 8 9 10

Q90% 0.941 0.765 0.642 0.560 0.507 0.468 0.437 0.412

Q95% 0.970 0.829 0.710 0.625 0.568 0.526 0.493 0.466

Q99% 0.994 0.926 0.821 0.740 0.680 0.634 0.598 0.568

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Reportable Results

g 8.1326 mg/mL was rejected from the mean as an outlier with 90% confidence.

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Group Nominal Analysed concentration (mg/ml)   RME Precision % Difference from Mean

  inclusion 1 2 3 4 Mean (%)from mean 1 2 3 4

  (mg/ml)             (%)        

2 10 9.6428 [8.1326] 9.9601 10.022 9.87 -1.3 2.06 -2.35 - 0.86 1.49

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Example 3

g UV Method – controls usually reportable as <LOQg One sample (from 3) showed a response >LOQg Full spectrum scan did not show a test item responseg No dilutions available to re-readg Time sensitive as pre-dose analysis!

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Contingency analysisg The next 3 samples were read <LOQg Full scans were done of all controls = clear of test item

responseg Rejected the initial sample result as anomalous as 5/6

controls were <LOQg Full investigation was not required as able to

demonstrate the control group was clear by full spectrum scans (of all controls) and results of 5/6 controls

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g Any Questions?

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