Back to the Top
The following message was posted to: PharmPK
Dear Member,
I would like know what could be reasons of getting multiple peaks in
Plasma Profile in Pharmacokinetic or Bioequivalence studies. How can
these be explained from analytical or Pharmacokinetic point of view.
Regards
Mkv
[What sort of compound? Is entero-heptaic recycling possible? Were
the subjects feed later in the study? - db]
Back to the Top
I do not know the analytical system you are working with first all
check the system thoroughly for possible contamination.
Check the standards you have used. Cleanliness of your glassware.
If using HPLC replace the needle wash mobile phase usually 50:50
methanol water.
Design a good protocol for cleaning glassware to avoid contamination.
Before you start blaming the subjects
s.o.o
Back to the Top
I am not sure what kind of detection method you are using but I
assume you are using LC/MS/MS. One of the possibility could be that
you are getting an "in-source" fragmentation. For an example, you are
measuring a parent compound with Q1/Q3 pair of 428/175 with the
retention time of 3.5 min. You have another peak at 2.5 min. This is
possible if you have a metabolite with glucuronidation and if that
has these fragments (428/175) you will see this on your chromatogram.
The mass of this metabolite will be at 604 but since it also has 428
and 175 fragment you will see it with a method allowing good
separation. The metabolite could be any, I used glucuronidation as an
example.
My approach would be to run a full scan mass spectrum of sample with
Cmax concentration and identify molecular ion for that peak and see
if is a legitimate biotransormation or not. Select mass range of at
least parent +300 amu. Select the MS parameters to give maximum
signal for molecular ion.
I assume you do not see this multiple peaks in your standards. If it
is a metabolite you should see a similar PK profile as the parent
compound in terms of clearance.
I hope this helps.
Regards,
Anila
Back to the Top
The following message was posted to: PharmPK
Dear All
I am totally agree with Anila, I also seen such peaks in plasma and
urine, due to metabolite having same fragments in pk studies. This can
be easily judged when such peak was not present in calibration
standards. IF present in standards then it may be due to impurity or
compound was a racemic mixture.
Rahul patil
Research Scientist-II,CCO,
Advinus Therapeutics Pvt. Ltd.,
International Bio Tech Park,Bio Resource Center,
2nd Floor, Phase-II,Hinjewadi, Pune-411057
Back to the Top
The following message was posted to: PharmPK
Dear All,
There is a double peak phenomena in plasma concentration profiles
that is
not so unusual.
Usually in mean data this phenomena disappear but in individual
profiles it
may be usual.
It may be due enteroheaptic recycle, bad formulation, absorption
windows,etc.
Sima Sadrai, PharmD, PhD
Associate Professor
Department of Pharmaceutics
Faculty of Pharmacy
Tehran University of Medical Sciences
Tehran
Iran
Email:sadrai.aaa.sina.tums.ac.ir
|
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 "Multiple peaks" as the subject | Support PharmPK by using the |
Copyright 1995-2011 David W. A. Bourne (david@boomer.org)