- On 13 Jul 2005 at 09:19:52, "Leach, John Kevin" (john_leach.aaa.merck.com) sent the message

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 - On 13 Jul 2005 at 19:00:56, "PACHOT Jean" (jean.pachot.at.oroxcell.com) sent the message

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 - On 14 Jul 2005 at 12:03:19, "Gurpreet Saini" (gurpreet.saini.-a-.ranbaxy.com) sent the message

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 - On 15 Jul 2005 at 13:01:27, marival bermejo (bibilina.-a-.yahoo.com) sent the message

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 - On 18 Jul 2005 at 09:50:23, "Gurpreet Saini" (gurpreet.saini.-at-.ranbaxy.com) sent the message

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

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 "Calculating a Papp from a mesenteric Loop Study" as the subject

PharmPK Discussion List Archive Index page

Copyright 1995-2010 David W. A. Bourne (david@boomer.org)