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Dear all,
There is one question on plasma concentration. The test compound was
given to monkey by IV at 2 mg/kg, but the plasma concentration for all
the sample time points were really low. Does anyone can analyse the
possible reason for me?
Any comments on it were highly appreciated.
Thanks in advance,
MJ
[Any idea on possible value for V or half-life. High V, low initial
concentration. Short t1/2, rapid drop in concentration. Assay sensitivity? - db]
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The following message was posted to: PharmPK
In addition to what David noted:
Drug binding to infusion device
Drug not stable in infusion solution
Assay gremlins -
wrong detection wavelength
Poor extraction from plasma
Drug binding to autosampler vial
Autoinjector error
....
William R. Wolowich, Pharm.D., R.Ph.
College of Pharmacy
Nova Southeastern University
wwolowic.-at-.nova.edu
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Dear
What is range for linearity and which analytical techniques your using
for quantification? What is the recovery ?
Thanking you
PRASHANT B MUSMADE
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In addition to what Dr. Wolowich indicated, it is not uncommon for
compounds to not pass through the filter when the IV formulation is
filtered to eliminate particles and pathogens. It is always best to
check the concentration of the IV formulation with the plasma samples to
eliminate the possibility that the formulation contains a compound that
is suppressing ionization in the Mass Spec. That assumes that your
assay is a Mass Spec assay.
Christopher Town, PhD
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The following message was posted to: PharmPK
There are too many possible reasons to list them all; they could be
technical/methodological or biological/physiological (or both).
Has the test article been studied in other species?
Has protein binding been determined with blood from the same monkeys?
Have microsomal stability studies been done with microsomes from the
same monkeys?
How (and where) was the test article infused and how (and where) were
the samples taken?
Best regards,
Frederik
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The following message was posted to: PharmPK
In addition to other experts comments
1. Analyze the formulation for in-vitro assay before dosing to check
weather compound is stable in formulation vehicle
2. Check the formulation is completely in solution form, there should
not be insoluble drug particle in formulation for which you need to
observe the formulation under optical and polarize light microscope
weather compound completely in soluble form.
Some time when compound is not soluble it will not show the
concentration in blood it might be deposited in some tissue and not
available for circulation
Regards
Ashok
-
Ashok Kumar Meena
Pharmaceutical Development, Jubilant Biosys Limited, #96, Industrial
Suburb, 2nd Stage, Yeshwanthpur
Bangalore-560022
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Dear all,
After looking at all possible reasons mentioned by the team.
The other possible reason could be compound's blood to plasma partition
ratio might be >1.
Thanks
Rajareddy Kallem
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The following message was posted to: PharmPK
Hello MJ,
Is your analytical method sensitive enough to assay the available concentrations?
Robert Lepage, M.Sc., CCRP
Director, Biopharmaceutics
Pharma Medica Research Inc
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