Back to the Top
The following message was posted to: PharmPK
Hello Everybody,
Does anybody know the approximate surface area in a 10cm section of
Sprague Dawley rat jejunum. Or does anyone have experience
calculating a
Papp from a mesenteric loop absorption study in sprague dawley rats?
Thanks
in advance.
Kevin
Back to the Top
The following message was posted to: PharmPK
Dear Kevin,
We have published a methodology how to determine Papp values from in
situ experiments (Boisset, M., Botham, R.P., Haegele, K.D., Lenfant, B.,
and Pachot J.I., 2000. Absorption of Angiotensin II antagonists in
Ussing chambers, Caco-2, perfused jejunum loop and in-vivo: Importance
of drug ionisation in the in-vitro prediction of in-vivo absorption.
Eur. J. Pharm. Sc. Vol 10, 2000, 215-224.)
May be this paper can help. In few words, for N = 25, the mean value of
1 cm2 of the anatomical surface area of jejunum sheet is 15.98 +/- 0.71
mg (mean +/- SEM). At the end of your transport study take the 10 cm
section (or whatever) of jejunum. Remove the content and dry the jejunum
section gently using a blotting paper. Then deduce the surface area of
your intestinal section according to its weight (in mg).
Hope this may help
Jean PACHOT, President & CSO
Oroxcell SAS
www.oroxcell.com
Parc technologique Biocitech
102, Rte de Noisy
F-93230, Romainville
jean.pachot.at.oroxcell.com
Tel/ +33(0)1 41 83 72 21
Back to the Top
The following message was posted to: PharmPK
Dear David,
The area is the curved surface area of the intestine which is the
curved surface area of a cylinder. This area is being exposed to the
drug solution.
so 2prl, length is 10 cm and radius taken in most of the papers is
0.18cms for rat jejunum
so the area comes out to be 2*3.14*0.18*10 =11.304 cm2
The effective permeability can be calculated by ln(Conc. out/
conc.in)/2prl * flow of drug solution in intestine (0.1-0.2ml/min)in
insitu single pass rat gut model.
what i feel is if you process and analyse the mesenteric samples
(Conc. out) and drug solution (conc. in)in the same way, (Conc. out/
conc.in)/2prl * flow of drug solution in intestine will give you the
effective permeability.
Refer to Amidon and Lennanas papers on permeability studies
gurpreet saini
Back to the Top
The following message was posted to: PharmPK
Kevin
Gurpreet answer is more or less the approximation we
use with our Wistar rats and Doluisio perfusion
method.
but we take into account the volume of solution that
we introduce in the 10 cm loop.
for experiments in duodenum (10 cm from stomach to
treizt ligament) we use a volume of 2 mL. This
corresponds to a radious of 0.25 cm and then to a
surface area around 15 cm2.
when we perform experiments in jejunum and ileum the
estimated radious is similar to the value Gurpreet
recommended of 0.18 cm.
marival
Back to the Top
The following message was posted to: PharmPK
Dear Kevin
May be you are filling the intestine with the drug solution
(we use a volume of 2 mL)
The calculation i have written before is for single pass rat gut
model with constant flow rate using pump.
Gurpreet
PharmPK Discussion List Archive Index page
Copyright 1995-2010 David W. A. Bourne (david@boomer.org)