Back to the Top
Dear all,
If I run a full curve samples from 08 volunteers (from a total of
24vol) and my internal calibrate points did not seems good (maybe the
LC-MS-MS was not stable enough) can I discharged the full samples
from the 08 volunteers, make a new extraction and run again? It would
be acceptable for a bioequivalence study?
Thanks
Ana
Back to the Top
The following message was posted to: PharmPK
Do you have acceptance criteria for your internal standard? Do you have
a re-assay specifications ? Did your analytical curve and QCs meet your
acceptance criteria? If the assay failed you can repeat, since there
were no results form the first analysis. If the assay passes but you
suspect an issue with the internal standard for the unknowns only- you
should be abel to rerun given that you have defined internal standard
acceptance criteria and these samples failed to meet that acceptance
criteria. If you do not have internal standard acceptance criteria, you
may be able to write a deviation, described acceptance criteria for the
IS, explain why you put it in place after running samples and justify 1)
rejection of the initial result and 2) re-assay. Discuss with your own
QA the path forward.
--
Ed O'Connor, Ph.D.
Laboratory Director
Matrix BioAnalytical Laboratories
25 Science Park at Yale
New Haven, CT 06511
Web: www.matrixbioanalytical.com
Email: eoconnor.aaa.matrixbioanalytical.com
Back to the Top
If you are submitting this data to ANVISA (Brazil) then I would say
they can raise some doubt on your method as they clearly state that
not more than 20% of total samples should be reanalysed.
It seems that your batches have passed the acceptance criteria so on
what basis do you claim that LC-MS/MS was unstable? What is the
garuntee that the instrument was stable for rest of the volunteers?
Do you have definitions for stable and unstable LC-MS/MS or any
documented procedure to identify?
It is not advisable to repeat the subject samples based on Internal
standard response. Since these standard are added to take care of all
the changes experienced by analyte during each step of procedure we
should not cut down their applicability by placing acceptance criteria.
Dr. Mandar Mote
Head Bio-analytical
CRO
Cadila Pharmaceuticals Ltd.
Ahmedabad.
Want to post a follow-up message on this topic?
If this link does not work with your browser send a follow-up message to PharmPK@boomer.org with "LC-MS-MS question" as the subject | Support PharmPK by using the |
Copyright 1995-2011 David W. A. Bourne (david@boomer.org)