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The following message was posted to: PharmPK
Hello all,
I want to know whether one can test the permeability of an anticancer
drugs using Caco-2 cells, as these drugs are cytotoxic to the cancer
cells.
Thanks in advance,
Samiulla
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Smiulla,
Interesting question because we generally "assume" that Caco-2 cells
act like a normal epithelial barrier in the gut. So if your drug kills
the Caco-2 cells, what will it do to gut epithelial cells?
As an alternative you can use the PAMPA system. It is a cell
independent system that measures permeability much in the same way as
with Caco-2 except you use a combination of lipid bi-layers with no
cellular components. Many companies use the PAMPA system for increased
throughput in initial permeability screens because it can be automated.
A starting point for information about PAMPA is the following URL:
http://www.pampa2002.com/images/pampa_story.pdf
Good luck!
Nathan
Nathan S. Teuscher, Ph.D.
Clinical Pharmacokinetics
NPS Pharmaceuticals
420 Chipeta Way
Salt Lake City, UT 84108
Voice: (801) 584-5379
Fax: (801) 583-4961
Email: nteuscher.at.npsp.com
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The following message was posted to: PharmPK
You can, you may be limited by what concentration you can use. You can
use
a diffusion marker and do trypan blue stains after the experiments to
determine if your monolayer is still intact and if the cells are still
alive.
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Dear Samiulla,
Caco2 permeability studies are generally shorter incubations and run
when the Caco2 cells have grown confluency. Most cytotoxic agents are
time dependent as well as concentration dependent so a 2 hour
incubation may have limited effect on cell viability depending on your
agent. Additionally, depending on the mechanism of cytotoxicity, since
the Caco2 cells are not actively growing and dividing, they are less
susceptible to many agents. Therefore, it is possible to run a Caco2
study on a cytotoxic agent. However, one should be sure to measure the
extent to which the cell layer is intact at the end of the study as
well as the beginning.
In a larger sense, if you are using the Caco2 assay for development of
an oral drug, it may be worth considering other routes of
administration for cytotoxic agents.
Regards,
Heather
Heather Kay Webb, Ph. D.
Senior Scientist
Preclinical Development
Scios, Inc.
820 West Maude Avenue
Sunnyvale, CA 94085
(408) 616-8394
webbh.-a-.sciosinc.com
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Hi Samiulla,
Your query is interesting butseeing the small magnitude of time drug
is in direct contact with caco cells in permeation studies, it appears
difficult for any anticancer agent to exhibit cytotoxicity and
alteration inpermeability of caco cells during the short permeation
study.
good luck!
Vijay Vishesh Upreti.
Drug Metabolism and Pharmacokinetics
Discovery Research, Dr. Reddy's Laboratories Ltd. (DRL)
Miyapur. Hyderabad-500 050. INDIA
TEL.+91-40-23045439(Ex 231)
www.drreddys.com
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The following message was posted to: PharmPK
Dear Samiulla,
I worked for a number of years on testing doxorubicin and vinblastine
permeability through Caco-2 cell layers. The best thing you can do is to
perform a cytotoxicity study (MTT assay is easier than trypan blue
experiments) first looking at concentration dependance setting the time
duration the same as you would use at looking at permeability. Then
choose a
concentration that is not toxic to perform your permeability
experiments. In
any case it is important to look at the cell viability before and after
experiments to make sure that everything is in order, by measuring the
extent to which the cell layer is intact.
I hope this helps!
Dr Begoņa Carreņo
Spain
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The following message was posted to: PharmPK
Dear Dr.Samiulla
Cytotoxic drugs can be tested for their permeability on a Caco-2 cell
line. You can see so many publications where people have done
permeability experiments using taxol which, as you know, is a cytotoxic
drug. I do agree that anticancer drug are cytotoxic to the Caco-2 cell
line also, but the factor that may play a pivotal role is incubation
time. Usually incubation is only done for a period of 3 - 4 hours
whichmay not effect the Caco-2 cells integrity to greater extent.
On the other hand, the other factor which may paly a pivotal roleis
the mechansim of action of the cytotoxic drug. If it is just a static
agent it willjust prevent further growth of the Caco-2 cell line . It
may not effect thecell as such to a greater extent. On the contrary,
if anti-cancerdrug is a cidal agent , then its effect on the cell
will be more . It may cause more damage if we incubate the Caco-2
system for longer times using such drug. It will be interesting to
check the integrity of the caco-2 cell line by incubating with a static
drug and a cidal drug for different time intervals.It may give us a
better picture .
This is just my assumption that mechanism of action of the cytotoxic
agent matters. I would be thankful if I can get valuble inputs from
variouseminent peopleworking in the area of permeability whethermy
assumption holds good or not .
Regards
Ravi Kanth Bhamidipati
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