PharmPK Discussion - Valsartan permeability

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On 25 Oct 2004 at 18:07:06, "jignesh surendrabhai kotecha" (jskotecha1.-a-.rediffmail.com) sent the message

Hello,
I would like to know the Biopharmaceutical class of VALSARTAN.
Since its absolute bioavailability is low (23%), i am getting higher
oral absorption value (high permeability class) in artficial membrane
assay. To justify above observation it is necessary to know to which
class its belongs.
thanks,
Jignesh Kotecha
Research Associate
Torrent Pharm. Ltd.
India.

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On 25 Oct 2004 at 13:16:50, "Whelan, Glenn" (WhelanG.-a-.NJC.ORG) sent the message


It is an angiotensin type 2 receptor inhibitor. This includes losartan,
irbesartan, candesartan , to name a few
Glenn Whelan, Pharm.D.
Adjunct Clinical Pharmacologist/Clinical Coordinator
National Jewish Medical and Research Center
1400 Jackson Street
Office J329
Denver, CO 80206
phone: 303-398-1448
fax: 303-270-2189
pager: 303-281-1375
Email: whelang.aaa.njc.org

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On 25 Oct 2004 at 12:47:10, "Rachel Mandell" (rmandell.aaa.rigel.com) sent the message


By absolute bioavailability I assume you mean F,  I think the equation
is
F=Fa*Fg*Fh
where Fa is the portion of the dose that arrives at the enterocytes, Fg
is
the portion of Fa that passes thru the gut wall in tact, and Fh is the
portion of Fg that makes it thru the liver into systemic circulation on
the
first pass. In order to make your bench top work match up with the
in-vivo
observations, it may be useful to consider some of the following,
Do you know what role gut metabolism (which you could test by doing
incubations with gut S9 and microsomal fractions) plays in the
bioavailability? Does your artificial membrane mimic gut metabolism?
Do you know if this drug is a substraight for influx or efflux
transporters
that may not be represented in your artificial membrane system? (PGp...)
Good luck!
-Rachel

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