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The following message was posted to: PharmPK
Dear Kshitij Soni,
Thank you for replying query on Investigator qualification.
Further, today we have faced a following case in Bioanalytical
Few subject samples (100) were taken for repeats due to "Unacceptable
chromatography (due to asymmetry)" and "Internal Standard Variation"
Upon repeat analysis it was observed that some of them (six) again
showed
"Internal Standard Variation". The results of these repeated samples
(six)
were within 20% difference of original value.
Should these six samples be accepted with
a) repeat value
b) to be considered as "MISSING"
c) original value
d) to be again considered for 2nd repeat
Could throw some light on this?
Dr Ashish Mungantiwar
Head-Bioequivalence and General Manager Medical Services
Macleods Pharmaceutical Limited, India
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Dear Dr. Mungantiwar,
Any of your proposals could be acceptable, depending on the
circumstances, but you (or the lab conducting the analyses) needs to
have SOPs in place that describe how to handle such cases. These
cases do occur occasionally during sample analyses. My experience is
that the regulatory authorities are most concerned that you have
objective and consistent procedures in place for handling such
occurrences, that you follow these procedures, and that all data be
available for review.
It is acceptable for a result to be called into question or even
disqualified for technical reasons (e.g., poor chromatographic
performance), and the circumstances and actions need to be described
in an SOP (or equivalent).
When a sample is reanalyzed, the process for selecting a value to
report needs to be described in an SOP. For example, this could be
confirming the original value when the repeat value is within a
specified range of the original value, or reporting the second value,
or reporting a mean. The SOP should specify when additional analyses
are needed, and when a result for the sample is not reportable
because of inconsistent results.
This is in response to the question:
Few subject samples (100) were taken for repeats due to "Unacceptable
chromatography (due to asymmetry)" and "Internal Standard Variation"
Upon repeat analysis it was observed that some of them (six) again
showed
"Internal Standard Variation". The results of these repeated samples
(six)
were within 20% difference of original value.
Should these six samples be accepted with
a) repeat value
b) to be considered as "MISSING"
c) original value
d) to be again considered for 2nd repeat
Thomas L. Tarnowski, Ph.D.
660 692-9296
ttarnowski1.aaa.aol.com
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Dr. Ashish,
Regarding repeats due to "Unacceptable chromatography (due to
asymmetry)" and "Internal Standard Variation"
Unusual asymmetry can be caused by many things, the two most common
are column aging and co-elution. If the column has aged, then all of
the peaks will show about the same degree of asymmetry and this will
be corrected by replacing the column. If only some peaks from some
subjects/samples show asymmetry, then this is often due to nearly co-
elution. The big concern is that perhaps the corresponding peaks from
all of the other subjects/samples may also contain the same
component, which is exactly co-eluting in those cases, and so would
be un-observed. Mass spec (MS or MS/MS), or diode array detection, or
a change in the chromatographic conditions to separate the components
of the asymmetric peaks, could address this.
Frank Bales
Frankbales.at.msn.com
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The following message was posted to: PharmPK
Dear Dr. Mungantiwar,
i agree with the statements given by Thomas
the repeat analysis procedures should be written as
SOP and in your case the six samples which were having
Internal standard deviation have to be reanalysed
according to your system of reanalysis because you
stated that repeat analysis to be performed for these
cases
unacceptable chromatography
internal standard variation
abnormal pk value
i will go for repeat analysis if come to this
situation
may be this will help for you
srinivas
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Dr. Mungantiwar,
In your case, for the samples that had acceptable chromatography upon
reassay - you can accept the repeat value based on acceptable
chromatography if the QCs and calibration curve within the range for
that run.
There should be an SOP or guideline for repeat analysis and
acceptance criteria stating reasons for repeat analysis. Reassays
should be done in triplicate if sample volume allows. The rationale
for the repeat analysis and the reporting of the repeat analysis
should be clearly documented.
Best wishes, Anila
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Dear Dr. Ashish,
I agree with what the experts have discussed here.
Even according to my view, these samples have to be taken for a
second repeat (unless otherwise your sample volume permits) since you
it would not be appropriate to compare the results of the repeated
value with the original value in this case. Since as per your SOP,
the original value will be considered to be invalid due to
Unacceptable chromatography or Internal Standard Variation.
I hope i am correct in my views. Coments from all you experts would
be of a great help.
Regards,
Rupali Morye.
Senior Research Associate- Quality Assurance,
Clinical Pharmacokinetics and Biopharmaceutics Department,
Wockhardt Limited,
India.
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Dear Dr. Mungantiwar,
I agree with most of the answers provided in the sense that you
should have an SOP describing how to handle repeats. The SOP should
also indicate how to report your repeat values.
Your SOP should also state if your reassay will be done in single or
duplicate. Personally, I do not see the advantage of doing
triplicates analyses. In addition, if you do duplicate or triplicate
analyses, the SOP should also state how to report these values (i.e.
mean of repeats) and how to deal if you one the duplicate/triplicate
values does not confirm the other ones.
Finally, Did you observed if these abnormal chromatography/IS
variation was within the same subject or was it random? We have seen
previously this type of behavior and sometimes they were related to
one particular subject.
Hope this information helps you in your dilemma
Regards,
Sylvain Mandeville, Ph.D.
LAB Research Inc.
sylvain.mandeville.-a-.labinc.hu
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