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Week 2 tutorial on quiz prep PART 3 | PharmacoPhoto | YouTubeToText
YouTube Transcript: Week 2 tutorial on quiz prep PART 3
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Video Summary
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Core Theme
This content provides a review of key pharmacological concepts, including stimulant laxatives, inverse agonists, pregnancy drug categories, and pathways of vomiting, preparing learners for quiz questions by clarifying potential ambiguities and highlighting critical information.
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Okay, we have just a few more questions
to look at in this tutorial and one of
them has to do with stimulant laxatives.
Just recall what the stimulant laxatives
were. Stimulant laxatives are a type of
laxative that works by increasing the
movement in the intestines.
Now that movement can be increased by
stimulating the nerves directly or by
enhancing the response of the muscles to
the nerve signals.
In complex pharmarmacological terms,
we're messing with the natural nervous
system of the git. So what would you
expect to happen if we use those over a
long period of time?
Indeed, those are going to cause
permanent damage to either the nervous
system control of the motility of the
git or to the git itself and or to the
git itself. So to the colon and uh that
that happens if they're used for a long
period of time. And as such, stimulant
laxatives should really only be used
when nothing else is working or as a
preparation for endoscopy or surgical procedures.
procedures.
So stimulant laxatives result in a
rebound constipation
that makes the person think that they
need more and then when they use it for
a long period of time the stimulant
laxatives damage the colon to the point
where the person can't move their feces
through the colon on their own. So the
question is going to say which of the
following is incorrect. And right now
we've got three of the five choices
showing. The first choice is stimulant
laxatives include bzicodal, sodium
picosulfate, senna and castor oil. And
that is a correct statement. Each of
those laxatives are termed stimulant laxatives.
laxatives.
The next choice is stimulant laxatives
exert a strong rebound effect causing
even more constipation. And as we recall
that is correct as well. In fact, as I
said before, it's suggested that the
stimulant laxatives only be used in
extreme situations and for short periods
of time because of that fact that the
git will get used to the medication and
it'll also damage the git and the nerves
and so forth. So, we'll become dependent
on it if it's used for a long period of time.
time.
The next choice is the one that can
change. So pay close attention to this
one from the list of stimulant laxatives
we investigated in module one bizodal
sodium picosulfate senna and castor oil
it's the sodium picosulfate is which is
the only stimulant laxative that cannot
be taken by suppository or enema and as
we see that choice there it is correct
each of those other stimulant laxatives
can be
used as a suppository. And if they are
used as a suppository, they'll act in a
matter of minutes to one hour, whereas
uh normal is going to be about 6 to 15
hours. But sodium picosulfate is a pro
drug and it's activated by intestinal
bacteria. In order to be changed into
the active form, it's going to actually
have to be down there for a while. It's
going to have to be in the area of the
intestinal bacteria. So sodium
picosulfate is totally useless if it's
taken as a suppository.
And another choice is that stimulant
laxatives can result in electrolyte disturbances.
disturbances.
And that is correct as well. It's
another one of the reasons that we have
to be careful when using stimulant laxatives.
laxatives.
And just think of the amount of fluid
that's being excreted in a short period
of time. And that explains the fact that
it results in electrolyte changes.
The final choice is none of the choices
are correct or choose this if all other
choices are correct. And if the question
appears exactly as we've just taken it,
then the answer none of the choices are
correct would be the best choice. But as
I said before, I reserve the right to
change this one. And the way that I
would actually change it would be that I
would talk about the laxatives that
cannot be taken as a suppository or by
enema. So for instance, if I said from
the list of stimulant laxatives we
investigated in module one, castor oil
is the only stimulant laxative that
cannot be taken by suppository or by
enema. Of course, that statement would
be the incorrect statement. So just
remember on this one, if I change
anything about the question, it'll have
to do with the ones that cannot be taken
by suppository or by enema.
I just don't want you to just remember
that the question on stimulant laxatives
is none of the answers is correct. I
want you to know a bit more about them
because of the safety issues around
Okay. So unless we have any questions on
that, what I'll be doing is going to
another question.
So the question has to do with inverse
agonist obviously but um inverse agonist
will be the closest two and you can see
three different ones on your screen
right now and there will be another two
uh the ones that are seen on the screen
are an inhibitor an agonist a partial
agonist and then there's two choices
that are missing which is choose this if
the inverse agonist does not resemble
any of the other choices is and also an
antagonist. Okay. So to understand this
I just need to explain what type of
receptor an inverse agonist can bind to.
When I explained it in module one I used
a receptor involved in an ion channel
because it's the easiest way to picture
it. But actually uh the ion channel
receptor isn't normally the kind of
receptor that can be involved in inverse
agnus. But let's get that simplistic
picture with that type of receptor. So
normally when a receptor of any type is
on a cell surface,
there needs to be a binding of the
natural liand to the receptor in order
for it to have any of those followon
effects that are associated with the
lian binding. In other words, when there
is no binding of the natural liand to
the receptor, the receptor is
functionally silent. it's just sitting there.
there.
And uh the thing is that for certain
receptors, just the fact that the
receptor is on the cell surface means
that there's going to be some what we
call constitutive activity.
It cannot be fully turned off. So
there's a little bit of activity all the
time. And that type of receptor can be
acted on by an inverse agonist. Now an
inverse agonist not only blocks the
receptor but it also decreases the
constitutive activity that some of the
receptors have. So that's explained in
this picture right here. But like I say,
it's be the better example is really the
anti-histamines because those are all
inverse agonists. The reason is because
the histamine receptor
is a receptor that will just in itself
just by the fact that it's on the uh
surface of the blood vessel,
the blood vessel wall, it's going to
result in a little bit of vasoddilation
and increased permeability. Just the
receptor, just simply the receptor. But
then when we take an anti-histamine,
it's going to actually not only block
the histamine from binding onto the
blood vessel, but when it's on that
receptor, it actually blocks that what
we call constitutive activity. It
actually um yeah is it's better than an antagonist.
antagonist.
So if you look at the question, an an
inverse agonist would be closest to
which of the following? An inhibitor?
Well, we know that's not going to act as
an inhibitor because of the fact that
inhibitors act on enzymes and not
receptors. So, that's categorically incorrect.
incorrect.
An agonist, remember, agonists would act
like the natural liand. So, that's
incorrect as well. We're talking about
medications like anti-histamines.
A partial agonist is also incorrect. A
partial agonist is a medication that
produces a small percentage of
simplistically speaking it's it produces
a small percentage of the effect that a
full agonist would have.
One of the choices that's not seen is
choose this if the inverse agonist does
not resemble any of the other choices.
And at this point that's the correct
choice. But uh question uh the other
choice that's going to be seen is
actually uh an inverse agonist is very
much like an antagonist. The other
choice is uh that it will be act as an
antagonist and indeed inverse agonists
are very much like antagonists. The
difference is that it's a little bit
better than an antagonist and it blocks
the constitutive activity.
So that one is important to know because
a lot of medications are called inverse
agonist and then I don't want you to go
out there and and say well actually we
never learned about inverse agonist. So
does anyone have any questions on that one?
one?
Okay. Then I'll slip in one of the two
twopoint questions that you will need to
answer in the way that I present it here
in the tutorial. The question that's
going to be in the quiz is going to read
like this. Explain what was described in tutorial
tutorial
as being the most important point to
remember about pregnancy categories.
Obviously, we're going to be talking
about the Australian pregnancy
categories. And at the beginning of this
tutorial, I said a few words about that
already. The very first thing that
you're going to have to put in your
answer in order for it to be deemed as
uh getting any credit is this right
here. The Australian pregnancy
categories are not strictly hierarchical.
hierarchical.
So you would actually say that the
Australian pregnancy categories are not
strictly hierarchical. Please don't put
it into your own words. I'm going to put
that into the chat box right now.
And you can copy it and paste it. Yeah,
it's in the chat box right now. So of
course what that means is that it's not
arranged in order of safest to least
safe drugs. But I need you to say the
Australian pregnancy categories are not
strictly hierarchical. The spelling of
hierarchical is h i e r a r c h i c a l.
So just to explain that again. While
pregnancy category A, C, D, and X get
more dangerous to the fetus as it goes
from A to X, pregnancy category B drugs
are drugs that lack data from humans.
And as such, pregnancy category B is
actually based on animal studies.
So you can get all of that in about 50 words.
words.
I don't want you to go over 100 words
because you're not going to get any
points for super explaining it and I
don't want you to run out of time for
the other questions. So, you can go to
the TGA website and they're the ones
that actually say that they're they're
the ones that say Australian pregnancy
categories are not hierarchical.
Um, but uh but they say a little bit
more too. They say the Australian
categorization system differs from US
FDA categorization. The categorization
of medicines for use in pregnancy do not
follow a hierarchical structure. And
then there's a few points below that.
Human data are lacking or inadequate in
drugs in the B1, B2, and B3 categories.
Subcategorization of the B category is
based on animal studies. And another
point is the allocation of a B category
does not imply greater safety than a C
category. So those are kind of important
points. You can look at those up at the
TGA, but basically all you really have
to do is say that the Australian
pregnancy categories are not strictly
hierarchical. And then something about
the fact that while pregnancy categories
A, C, D, and X get more dangerous to the
fetus as it goes from A to X, pregnancy
category B drugs uh are ones that lack
that human data and as such the B is
based on animal studies.
So, is everyone very clear about that?
The twopoint question.
And finally, the very last question
that's going to be in this tutorial and
that will be in the quiz has to do with
the four pathways that lead to the
vomiting center.
So, let's just go over those really
quickly. And it was part of the
condensed version of chapter 5 in module one.
one.
uh in that module I explained that there
were fi four different pathways. There's
one pathway that goes from the higher
brain center to the vomiting center and
that's responsible for vomiting that's
associated with extreme pain or
psychological distress and vomiting from
that pathway is best treated with the benzoazipines
benzoazipines
laurazzipam dasipam the azipam or azolam drugs
drugs
there's another pathway way that goes
from the vestibular area to the vomiting
center. And that one is the one that is
going to use the histamine one and
acetylcholine. That's the one for motion
sickness. It's also the one that uh
somebody from with minè's disease would
actually be using when there's damage to
the vestibular area uh and there's
vomiting that's involved. That is the
pathway. It uses acetylcholine and
histamine one. So of course the first
generation antihistamines are the very
best ones because they kind of block
both. They block histamine one
intentionally and they also block uh
acetylcholine as kind of almost an
unintentional action.
And uh then there's also the strictly anti-olineric
anti-olineric
drugs like hyiosine and scopo scopoleamine.
scopoleamine.
Those are uh really good if there's also
some types of spasm in the git along
with the motion sickness.
So those are the strictly antiolineric
drugs. Now if a person is receiving
chemotherapy that's going to do a number
of things at the same time. That's going
to for instance it's going to damage the
stomach. It's going to act on the chemo
receptor trigger zone and other
pathways. And all of the pathways that
are affected by chemotherapy induced
vomiting have a very specific type of
neurotransmitter called serotonin 3 or 5HT3
5HT3
as the neurotransmitter. So of course
the very best medication for
chemotherapy induced uh vomiting is on
dancetron or other se
drugs those 5htt
receptor antagonists
and there is another neurotransmitter
that's involved in vomiting that
originates from the git or the
cheoceptor trigger zone and that
neurotransmitter is dopamine 2. So,
dopamine 2 antagonists are going to be
effective in chemotherapy induced
vomiting and they're quite inexpensive.
But the problem is that dopamine 2 has a
lot of actions in a lot of different
parts of the body. So there's movement
disorders and all sorts of uh problems
that are associated with dopamine 2 antagonists
antagonists
like uh for instance procloroparine
and uh and yeah they're simply not the
first line therapy for many people let's
put it that way. So hopefully you
understand the four pathways and now
that we've uh reviewed those path
pathways, let's take a look at the
question that will be seen in the quiz.
The question is going to uh be uh choose
the person who is about to receive the
wrong medication for their condition. So
the very first choice on that is well
the first choice that I'm giving you
right now obviously these are going to
be seen in random order. Hanvi has
vomiting that results from extreme pain
or the psychological stress of seeing
something very disturbing and is most
likely to benefit from the benzoazipines
and that is actually a correct treatment
for vomiting from psychological stress
of seeing something very disturbing. The
suffix aopam and the suffix aolam. Those
azopam and azo lamb drugs are bzzoazipines
bzzoazipines
and those are the best medications for
that type of vomiting. So the next
client is Melissa and she's going on a
boat and is very susceptible to motion
sickness and is about to receive a first
generation anti-histamine called dipenhydramine.
dipenhydramine.
And as we will see when we discuss the
early antihistamines, a first generation
antihistamine and uh the early
anti-histamines, the first generation
anti-histamines blocked both of the
histamine and the acetylcholine
receptors. So because of that,
dyenhydramine is probably the best
motion sickness medication that a person
could actually uh get as long as the
person can tolerate it. Another client
is Joe who has eaten some stale shellfish
shellfish
and uh that has bacterial toxins and
although undancetron would probably stop
the nausea and vomiting it is decided
that uh Joe Joe receives no medication
so that the toxins are naturally
expelled from the body and it's also
decided that he should get fluid and
electrolytes and be monitored closely
and As that choice stands
here, Joe is about to get the right
medication. And if the question is
exactly the way that appears there, then
do not choose it because we're looking
for the incorrect statement. But this
one could actually change. So take note
of this because now Joe is about to
receive on dancatron.
Well, it would probably be effective at
stopping the nausea and vomiting, but
the problem is that all of those
bacterial toxins and the bacteria
themselves are going to start to
proliferate. All of that is in the git.
It remains in the git. We don't have our
natural ability to get it out and it
could result in big problems for Joe and
he might have to actually go to the
hospital. So uh so if it is this choice
then that is definitely the incorrect statement.
statement.
And another client is Jan who is on
chemotherapy and is about to receive on
densetron the selective 5HT3
receptor antagonist and now that is the
correct medication. Jan could also be
prescribed for instance prochlorazine
as well but uh andensatron has the
fewest side effects and it would be the
most effective. So finally the final
choice on this one is choose this if
each of the people on the list is about
to receive the correct treatment for
their specific type of nausea. [snorts]
And this is the correct choice if Joe is
about to receive fluid and electrolytes.
But of course, if Joe is about to
receive on dancatron, then that is the
incorrect statement. So, does everybody
understand that one? Okay.
Okay.
If you have any problems on any of these
questions, then post them into the chat box
box
uh or you could email me. And in the
meantime, what you need to do is
practice those activities. Remember the
uh module one has a number of short
lessons and each one of the short
lessons is is followed by an activity.
Remember the way in which I get the
questions for the multiple choice
questions is I I looked at each one of
those activities and said can I make
this into a multiple choice question? If
I was able to make it into a
multiplechoice question, then I've
included it the multiple choice question
in the quiz. So, make sure that you go
through those activities again and
you're going to do really well in this quiz.
quiz.
Okay, everyone. Um, thank you for
joining me here and we're going to see
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