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Dear to all
I am developing method for estimation drug in fixed dose combination
product . In that one drug molecule is very much polar as compare to
other and observe that it will not retain on C18 without ion pair
reagent. By using ion pair mobile phase one drug is eluting at 6.4min
while other is 18.6 min.
i want to know as per system suitability and regulatory point view is
separation factor is issue in the present retention time or i have
to still optimise method ?
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Dear Prashanth
As per my knowledge regulatory talk about only resolution between two
peaks( >=2.0). So I feel you can go ahead with your method, But to
save the analytical run time still you can optimize your method.
With regards
R.Shetty
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Dear Prashant,
You might not be able convey what you want. Are you saying about the
resolution in peak or else.
No one can say without having resolution in the peaks whether they
are well separated. But since you are saying one is eluting at 6.4min
and another at 18.6 min then they must be well separated if not then
your peaks might be broad.
Best Regards
Vineet Singh
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The following message was posted to: PharmPK
Prashant,
There are no System Suitability or Regulatory restrictions I know of,
but do be careful not to have "ghosting", where a late-eluting
degradant shows up in the run for the following injection. The "rule-
of-thumb" to avoid this is to run for three time the RT, which would
be about an hour per run if this is isocratic.
Regards,
Frank Bales, Ph.D.
frankbales.at.msn.com
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Dear Prashant,
As par my understanding, your peaks are well separated. There is no
regulatory requirement for how close your peak should be separated
from each other. But yes, it would be better for you to have short
run time with resolution more than 1.5 or 2. If you can manage to
have method of 10 or 12 min it could speed up your final study.
Bhagwat
Research Associate
Ranbaxy Res. Labs.
Gurgaon
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Dear Bhagwat,
He questioned for different context. His question is basically he was
this method for bioanalytical one and whether this work or not. My
opinion is it will work but one must establises the LLOQ and HLOQ and
apart repeatability in the methods
Vineet singh
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If your peaks are not so broad then I don't think you have problems
with separation and resolution of peaks. However, you better pay
attention to degradation products that can happen over time
(especially with longer run times). The best way to approach this is
run the first few standards containing the two compounds for 3- times
the retention time of the latest compound to emerge and observe if
any degradation products are eluted out in subsequent runs. Once you
resolve this, you can still optimize run times to be shorter (if you
have good separation), just by using a gradient method of elution.
I hope this helps.
Murad
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Copyright 1995-2010 David W. A. Bourne (david@boomer.org)