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The following message was posted to: PharmPK
I would like to know if anyone has seen difference in oral %F when two different formulations like 0.5% MC pH 6.5 suspension vs 0.05M Citric acid pH 2.5 solution are used.
In a literature (reference listed below), it is listed that when 0.05% citric acid, pH 2.5 solution used in dog the oral %F increased to 72% compared to 0.5M MC pH 6.5 suspension. The oral %F was 16% with 0.5% MC pH 6.5 suspension in dog.
It did not change orak %F in rat for the two above formulations.
Have you seen the difference in absorption in dog when these two formulations are used in dog?
Thank you in advance for your comments.
Reference: Drug-like properties: concepts, structure design and methods (page 68-70. E. Kerns and L. Di
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There are various possibilities so a little extra information might help.
Looking at physchem first:
Is your drug a weak base with very low pKa? If not what is it?
Do you know the gastric pH of your dogs and/or did you use a drug such as pentagastrin
to lower canine gastric pH?
What was the %F in your rats ?
David Turner, PhD
Principal Scientist - Modelling and Simulation
Blades Enterprise Centre, John Street, Sheffield, S2 4SU, UK
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