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The following message was posted to: PharmPK
Hello everyone,
Is there a standard procedure for the validation of the single pass
perfusion model used to determine the coefficient of drug absorption
across the intestine (in the rat). Are they reference drugs used to
validate the model ? if yes could you helpme to find the data related
to absorption coefficient of these reference drugs.
Thank you for your help
Frederic
--
Frederic Lagarce, Pharm-D, Ph-D
Inserm U 646, Ingenierie de la vectorisation particulaire
10 rue A Boquel, 49100 Angers
tel 33 (2) 41 73 58 55
fax 33 (2) 41 73 58 53
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The following message was posted to: PharmPK
Dear Frederic,
I am not sure there is any standard validation procedure for such
single-pass perfusion models.
But I think that you should try and perfuse the intestine with
non-absorbable markers such as Mannitol or PEG4000 to ensure the
integrity of the membrane and consider this as a model validation. I am
concerned that you will have difficulties to find reference drugs with
known absorption coefficients to get more confidence in your model.
Some experts using this method perfuse the intestinal lumen with a
solution of the drug with a non-absorbable marker. If you do so, when
you collect blood samples in the
mesenteric vein you should not get any Mannitol or PEG 4000.
Does it make sense?
Best regards,
Frederic
Frederic Doc
ACRITER - drug discovery consulting
visit our web site at : http://www.acriter-consulting.com
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The following message was posted to: PharmPK
FDA guidelines for biowaiver for Immediate release BCS class 1 provide
guidelines on ranking and valdiation of methods used for evaluating
permeability (caco-2, single pass, everted sac, etc) of drugs. I agree
with Frederic that PEG 4000 and mannitol (radiolabeled) are widely used
to check integrity of the membrane. Researches are also using phenol
red as zero permeability marker.
Best regards
shanthakumar
University of utah
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The following message was posted to: PharmPK
Hello Frederic,
Indeed, there might not exist a validation procedure for intestinal
perfusion per se, but you can monitor the integrity of the intestinal
segment pretty well by adding different marker compounds. I am including
some references where antipyrine has been used as a marker for passive
diffusion, H3 d-glucose as a marker for carrier mediated transport, and
C14 PEG 4000 for the integrity of the intestinal wall. Advantage in
using the radiolabeled compounds is that you can detect them easily in
your perfusate samples and do not need to develop additional LC-MS or
other assays. These papers also provide the formulas for appropriate
calculations, permeability estimates for the markers, and other
references.
Fagerholm et al.,Comparison between permeability coefficients in rat and
human jejunum.Pharm Res. 1996 Sep;13(9):1336-42.
Fagerholm, et al..Regional intestinal permeability in rats of compounds
with different physicochemical properties and transport mechanisms.
J Pharm Pharmacol. 1997 Jul;49(7):687-90.
I hope you'll find these helpful.
Irene Lepist
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The following message was posted to: PharmPK
Dear Frederic,
If you are going to use the SPIP model in rat as a tool to estimate
human
intestinal permeability, you should have your own calibration curve
relating the data for rat obtained in your own lab and known human data.
Actually there are a limited number of drugs which their human
intestinal
permeabilities are known. Remember to use an non-absorbable water-flux
marker (PEG4000 or Phenol red) in all perfusion experiments to correct
the
outlet tubing concentration. The steady-state concentration of this
marker
in distal tubing is a proof of intestinal barrier function (viability)
and
its integrity as well. You may also use D-glucose and antipyrine as
markers for active and passive transport respectively. Although there
are
some reported Peff values for these two components in literature, you
should notice to their constant Peff values during the experiments. Hope
this helps.
I suggest you take a look at following papers:
J. Pharm. Pharmaco, 1997 (49), 687-690.
Pharm. Res., 1995 (12)(5), 693-699
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The following message was posted to: PharmPK
Hello all,
I would like to clarify a point of my previous message.
Someone contacted me to comment on the use of mannitol.
Based on his comments (thanks again John) I would like to apologize for
the confusion I did. Mannitol is used to check the Caco2 monolayer's
integrity but may not be used to do the same with intestinal membranes
as it can go through the membrane by paracellular phenomena.
Best regards,
Frederic
Frederic Doc
ACRITER - drug discovery consulting
visit our web site at : www.acriter-consulting.com
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The following message was posted to: PharmPK
Dear Frederic,
If you are going to use the SPIP model in rat as a tool to estimate
human
intestinal permeability, you should have your own calibration curve
relating the data for rat obtained in your own lab and known human data.
Actually there are a limited number of drugs which their human
intestinal
permeabilities are known. Remember to use an non-absorbable water-flux
marker (PEG4000 or Phenol red) in all perfusion experiments to correct
the
outlet tubing concentration. The steady-state concentration of this
marker
in distal tubing is a proof of intestinal barrier function (viability)
and
its integrity as well. You may also use D-glucose and antipyrine as
markers for active and passive transport respectively. Although there
are
some reported Peff values for these two components in literature, you
should notice to their constant Peff values during the experiments. Hope
this helps.
I suggest you take a look at following papers:
J. Pharm. Pharmaco, 1997 (49), 687-690.
Pharm. Res., 1995 (12)(5), 693-699
Back to the Top
The following message was posted to: PharmPK
Dear Frederic,
If you are going to use the SPIP model in rat as a tool to estimate
human
intestinal permeability, you should have your own calibration curve
relating the data for rat obtained in your own lab and known human data.
Actually there are a limited number of drugs which their human
intestinal
permeabilities are known. Remember to use an non-absorbable water-flux
marker (PEG4000 or Phenol red) in all perfusion experiments to correct
the
outlet tubing concentration. The steady-state concentration of this
marker
in distal tubing is a proof of intestinal barrier function (viability)
and
its integrity as well. You may also use D-glucose and antipyrine as
markers for active and passive transport respectively. Although there
are
some reported Peff values for these two components in literature, you
should notice to their constant Peff values during the experiments. Hope
this helps.
I suggest you take a look at following papers:
J. Pharm. Pharmaco, 1997 (49), 687-690.
Pharm. Res., 1995 (12)(5), 693-699
Back to the Top
The following message was posted to: PharmPK
Hello all,
I would like to clarify a point of my previous message.
Someone contacted me to comment on the use of mannitol.
Based on his comments (thanks again John) I would like to apologize for
the confusion I did. Mannitol is used to check the Caco2 monolayer's
integrity but may not be used to do the same with intestinal membranes
as it can go through the membrane by paracellular phenomena.
Best regards,
Frederic
Frederic Doc
ACRITER - drug discovery consulting
visit our web site at : www.acriter-consulting.com
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