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The following message was posted to: PharmPK
Dear All,
We observed a extra peak in the Chromatogram while analysing PK
samples of NCE in mice. As we work further with MS the molecular
weight determined as 229. But when we analyse other NCE's ( other 2
numbers) even there we got the same peak with same mass. We have
ruled out all the other possibilites of error. (As this peak is not
observed in predose samples and other QC samples, IS). Will there be
any problem with the group of animals we use for all the analysis?
Please suggest me to overcome this problem
Regards,
Martin
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The following message was posted to: PharmPK
Dear Martin,
you wrote,
(As this peak is not observed in predose samples and other QC samples,
IS)
If you mean to say that the peak is not observed in the blood samples
withdrawn from the same group of animals before dosing (predose
samples) then the possibility of any problem in the animal group doesnt
arise.
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Dear Martin
Some compounds selective under go chiral invertion when administered to
physiological system. The rate of inversion and kinetics needs a
detailed conduct of series of experiments/ Clopidogrel and lot other
drugs can be classical examples of them.
May be isomers/enantiomers getting seperated in same chromatoraphic
system !
Needs a gross investigation in chromatographic method :)
Conduct structural elucidiation of second peak in comparision with peak
of interest.
Thanking you and Regards
Vishwottam K N
Senior Scientist - Biopharmaceutical Research
SUVEN LIFE SCIENCES Ltd
Serene Chambers, Road # 7,
Banjara Hills, Hyderabad 500 034
Phone : 9140 2355 6039, 9140 3092 1169
Fax : 9140 2354 1152
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The following message was posted to: PharmPK
Dear Martin,
I think your question needs to be more specific.
You would have looked into the following, but in any case,
There are multiple aspects you may have to look into:
-Do the compounds (three NCE's) belong to the same chemical class.
-What is molecular weight difference between the NCE and the peak with
molecular weight 229.
-Have you adressed the metabolism - incubation of the compound with
mouse liver microsomes.
-Do you store your QC's. If you do, then stability may not be an issue.
-Why do you think the additional peak could be a problem.
-It might also be worth running in vitro stability studies in mice
blood and phosphate buffer.
Hope this helps,
Jagannath
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The following message was posted to: PharmPK
Dear Martin,
As you may have noticed through my e-mails with
Ferderic these days I think about the dosing
formulation a lot. Is it possible that the extra peak
is coming from dosing solution/formulation? Does the
size of this peak get smaller over time or it is
consistent? If it is consistent then likely the dosing
formulation theory is out the window and probably
there are some chromatographic complications are
involved.
Rostam
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