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This is Howard Maibach in
San Francisco trying to
bring you up to date
about an ancient technique from
the previous century
in vitro per
cutaneous penetration test or in
vitro permeation test and
why it's important and what
is the advantages are.
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We can thank the United States
Food and Drug Administration
for rescuing it and
bringing it up to date.
Obviously in the load data
especially in the
animal that we're
most interested in
namely usually the
Homo sapiens has
many advantages.
But is in many laboratories,
awkward because it requires
human volunteers and it requires
a great deal of regulatory work.
The IVPT has been around
since before and during
the second world war.
It has many many purposes
which we will go
into and can be adapted
into many laboratories.
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Its history starts in
1939 when a professor
of internal medicine used it
to study skin physiology,
namely insensible of water loss.
The water that comes
through your skin at
rest in vivo in man it's now
called not insensible water
loss today it's called
TEWL, trans-epidermal
water loss.
In 1939, also
brought the chaos of
the second world war.
Many countries were
very concerned that
the chemical warfare agents
that created such chaos in
Belgium in World War I would be
used again in World War II.
That led the English
government to start
the laboratory of
Dr. Traeger in 1939.
Dr. Traeger developed
a stationary in
vitro system which
was used until
the present time and is
still being refined.
His textbook, if you
can get a copy of
it, is essentially
the equivalent of
the Bible, the Old and
the New Testament.
He foresaw many of the
refinements that
followed is work.
Originally, it was used for
chemical warfare agents
but now it's used
for all types of assays to
determine relevance to man.