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week 2 tutorial on quiz prep PART 2 — Transcript

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0:00Okay, for the next question, you're
0:03going to need to know just five
0:05suffixes,
0:06which are the ones that I've talked
0:07about most in module one. So, the
0:10question will be worded, "The following
0:13are fictitious drugs. Using your
0:16knowledge of drug suffixes, choose the
0:19one that, for instance, would be a
0:21benzodiazepine."
0:23Or I may say, "Choose the one that is a
0:26beta blocker, or the one that is a
0:28corticosteroid, or the one that is an
0:30alpha blocker, or the one that is a
0:32proton pump inhibitor." I don't want to
0:35give you the exact question, because
0:37you'll just learn one suffix, and this
0:40way you're going to learn five suffixes.
0:43So, there are five fictitious drugs.
0:46Obviously, if you look up a fictitious
0:48drug, you're not going to find anything
0:51about that drug. It doesn't exist. So,
0:54uh remember what the generic name is.
0:57It's a shortened version of the chemical
0:59name.
1:00So, for metoprolol, that is an
1:03abbreviated version of this full
1:06chemical name. And you see exactly how
1:09we actually derive that metoprolol from
1:11that chemical name.
1:14Other
1:15drugs are not as straightforward as
1:18this. They You won't find exactly
1:21the uh the word exactly in the chemical
1:25name, but you get the point from this
1:27example.
1:28We're never going to need to know the
1:30chemical name, but it is best to know
1:33the generic name, and normally we learn
1:35at least one of the popular brand names
1:38as well. But, it's the key portion of
1:41the drug name that we look for to
1:43identify drugs that we've never heard
1:46before.
1:47For instance, beta blockers
1:49uh have the suffix o l o l.
1:54And for corticosteroids,
1:57they're a bit more difficult because
1:58corticosteroids have different affixes,
2:02and some of them come in the middle
2:04portion of the word, some of them come
2:06as prefixes, and some of them come at
2:08the end portion known as a suffix.
2:11Most of them actually come at the end
2:12portion, but like I said, it's variable.
2:15And uh suffixes are are actually uh
2:18coming at the end portion of the word.
2:21This is an example of different
2:23corticosteroids.
2:24Uh look for the pred, the asone, and the
2:28court in the
2:31in a portion of the generic name, and
2:33that's going to be a corticosteroid.
2:35Corticosteroids are so diverse, though,
2:37that they have many different affixes.
2:41Those are the most common, the pred,
2:43asone, and court in the uh somewhere in
2:47the name.
2:48Uh going back to this list, the zosin is
2:52uh is z o s i n is an alpha blocker.
2:55Remember we learned that in module two.
2:58Uh prazosin, doxazosin, those are used
3:02for benign prostatic hyperplasia,
3:04they're used for hypertension,
3:07but they actually selectively block the
3:10alpha receptor.
3:12Uh the alpha adrenergic receptor. And
3:15what is the oprazole, o p r a z o l e
3:20suffix? It's a proton pump inhibitor.
3:24Remember that was in module one when we
3:27talked about uh them being an
3:29irreversible inhibitor. The azepam or
3:34azolam
3:36is a benzodiazepine.
3:38Remember benzodiazepines are like Xanax
3:41and Valium.
3:43They're a medication that's used for
3:45anxiety.
3:47So, there's just five different suffixes
3:49that you need to learn, and I guarantee
3:51that one of those is going to be in the
3:53quiz. And hopefully that's enough
3:55information for you to get in that habit
3:57of looking for that little snippet of
3:59the word of the drug name of the generic
4:02drug name to identify which drug class
4:04it is actually in.
4:08Okay, so hopefully you do develop that
4:10habit with those five examples and we'll
4:14go on to the next question. The next
4:17multiple choice question has is this one
4:20right here. It's which of the following
4:22is incorrect about cellular receptors.
4:26So the first choice is when the cellular
4:28receptor is bound by the natural ligand
4:31or a drug that mimics the natural
4:33ligand, that is the signal for the cell
4:35to do something.
4:37And if you take a look at
4:40this right here, this diagram right
4:42here, it's depicted in this diagram
4:45where the ligand binds to the receptor
4:48and indeed that is the signal for the
4:50cell to do something. When our cells
4:53start to communicate with each other,
4:55that's the very process that we use. We
4:58send out a messenger molecule and then
5:00it's going to land on the proper
5:02receptor on certain cells and that's the
5:05cell that's that signal for the cell to
5:08do something. So it's our communication
5:10network.
5:12The second choice is cellular receptors
5:14can be increased or decreased by the
5:16cell
5:17thereby increasing or decreasing the
5:19number of messages to that cell.
5:22And this is depicted in this diagram
5:24here with the insulin receptors.
5:27One of the notable examples with respect
5:30to this has to do with the number of
5:32opioid receptors on the cell surfaces
5:36when we start taking opioids on a
5:38regular basis.
5:39It's part of the reason that when
5:42somebody takes opioids for a few weeks,
5:44they become tolerant of the opioids and
5:47they need more. And because of the fact
5:49that we are decreasing the number of
5:52opioid receptors on the surface of the
5:55cell of the surface of the neuron.
5:59So, indeed, cellular receptors can be
6:01increased or decreased by the cell,
6:03thereby increasing or decreasing the
6:05number of messages to that cell.
6:10And so, that statement it was correct.
6:12And the next one, the cellular receptors
6:14that most of our drugs bind to in order
6:17to perform their therapeutic actions are
6:19involved in communication between other
6:22cells or other parts of the body. And
6:24pretty much that's something that we've
6:25kind of taken already. That is a correct
6:28statement. There are a very few
6:30exceptions to that rule, but generally
6:33the drug is basically acting to
6:35communicate with the cell as it binds to
6:37the receptor.
6:39And statement D is most commonly when
6:43the cellular receptor is bound by the
6:45natural ligand, that results in a
6:48conformational change in the shape of
6:50the receptor, uh thus signaling other
6:53actions in the cell.
6:56And that one is correct as well. For
6:59instance, when two insulin molecules
7:02bind to their insulin receptors depicted
7:05in this picture, the protein changes
7:08shape, and that change of the shape
7:11actually is the start of a cascade that
7:14happens inside the cell.
7:17Uh the one statement that is missing
7:19from the
7:21PowerPoint is
7:23choose this one if you believe that each
7:25of the comments about cellular receptors
7:27is correct. Just remember with this one,
7:31you can get really pedantic about it.
7:34And And you can get really pedantic
7:36about just about anything in
7:37pharmacology. But please don't think
7:39that I'm trying to trick you in any of
7:41these questions. It's just testing your
7:44general knowledge,
7:46not your ability to pick up pedantic
7:50little points.
7:51So, there's always exceptions to the
7:53rule in medicine. Nothing happens 100%
7:56of the time, but this is an introductory
7:58pharmacology unit, and all of the
8:00statements in the question here is
8:04generally correct.
8:06So, if you would like to contest that
8:10answer or any of the answers that we go
8:12through, or the
8:15questions within the modules as well.
8:19So, there's activities in the modules
8:21and some of the questions on the quiz
8:23are going to be in that from the
8:24activities. If you're going to question
8:27any of the answers to those, I want you
8:30to do it before the quiz.
8:33It is too late to contest it after
8:35you've taken the quiz and you're
8:37desperately trying to find some source
8:40that actually makes it look like your
8:42answer was correct.
8:44So,
8:45yeah, just make sure that you contest it
8:48before that and we can talk about it and
8:50I'll tell you which answer to actually
8:52put down if it's in the quiz.
8:55Now, the next question is this one here.
8:59It has to do with Cmax or concentration
9:02max.
9:03Now, what is Cmax? Cmax is the maximum
9:07or peak serum concentration of that a
9:09drug achieves, okay?
9:12And it's kind of a standard measurement
9:14in pharmacokinetics, and it's important
9:16to understand it because of the fact
9:18that with the understanding of that,
9:20you're going to understand why one type
9:22of administration is chosen over
9:23another,
9:25important safety issues about, for
9:27instance, um
9:28drugs that are
9:31going to be administered via the lungs
9:33or drugs that are administered by IV,
9:36and so forth. So, it is an important
9:38concept. The question is going to go,
9:40which of the following is incorrect?
9:44And the first statement is Cmax or
9:46concentration max is the maximum or peak
9:49serum concentration that a drug
9:51achieves. And of course, that's is
9:53correct. That is the definition of Cmax
9:56or concentration max. It's the maximum
9:59serum concentration that a drug achieves
10:01after the drug's been administered.
10:04The next statement is a mode of
10:06administration that achieves a very high
10:08concentration max is going to result in
10:11that drug being metabolized faster in
10:13the initial stages of metabolism.
10:16So, if you take a look at these graphs
10:19here, that these two graphs. First of
10:22all, time is on the x-axis and plasma
10:25concentration is on the y-axis. Can you
10:28tell me which of these two would be
10:31depicting IV or administration by the
10:34lungs versus which one is depicting
10:38orally administered drug?
10:40Yeah, okay. So, the one that is on the
10:43right, the one that has a high Cmax is
10:46indeed the one that's inhaled or it
10:49could depict the
10:52type of Cmax that's evident in a
10:56intravenously
10:58administered drug as well.
11:00And the one to the left actually depicts
11:02the oral administration.
11:05And just by looking at the graph though,
11:07look at these and say which of those is
11:10metabolized faster in the initial
11:12stages.
11:14You You see how quickly the one with the
11:16higher Cmax is metabolized in comparison
11:19to the other in that first portion?
11:22And you may be thinking, you know, why
11:24is the one on the left, the oral
11:26administration, such a low Cmax? Well,
11:30when you take a medication orally, what
11:33happens is that it starts to get
11:35absorbed. And there's a whole process of
11:37getting absorbed. Some of it may
11:39actually go through the stomach, some of
11:40it may go through the intestines.
11:43And um it's a it's a longer process, a
11:46much longer process to even get
11:48absorbed. And then it goes into the
11:50liver first, and that's
11:53uh
11:54going to take some time to get
11:55metabolized and so forth. And that's the
11:58reason you have this low Cmax for an
12:02orally administered medication. And
12:04conversely, when you administer
12:06anesthesia by inhalation,
12:09you or you or you inject the drug, that
12:11goes straight into the blood, and it uh
12:14doesn't go through the liver at all.
12:16It's goes straight into the blood, and
12:18you get that response almost
12:19immediately.
12:21So, the statement, a mode of
12:22administration that achieves a very high
12:24concentration max is going to result in
12:26the drug being metabolized in the faster
12:29in the initial stages of metabolism, is
12:31correct.
12:33And the next statement is uh there is a
12:36greater potential for overdose side
12:38effects and complications with the mode
12:41of administration that gets the medicine
12:43into the system the fastest.
12:45And looking at this graph again, which
12:48of these is most likely to have side
12:51effects? And from the graph, obviously,
12:52it's very obvious. The one that has the
12:55highest concentration max or Cmax is
12:58actually going to end up with the
13:01greatest and there's a number of reason
13:03uh greatest uh side effects. There's a
13:04number of reasons for that, which we've
13:07uh taken in module one.
13:10Okay. And one of the other options is
13:14intravenous administration has a greater
13:16Cmax than oral administration, and that
13:19one is, of course, correct. Um I'm that
13:23that one's obvious. Uh and uh and final
13:26the final statement is when a drug is in
13:29high concentration, it is less likely to
13:32bind to enzymes or receptors that it's
13:35not supposed to bind to. And that one is
13:37categorically incorrect. In fact, it is
13:40the opposite. A correct statement would
13:42be when a drug is in low concentration,
13:45it is less likely to bind to receptors
13:47or enzymes that it's not supposed to
13:49bind to. In the modules, we explained uh
13:53that with this example in a low
13:55concentration,
13:56a selective beta-2 antagonist, for
14:00instance, would bind only to the beta-2
14:03receptor. But when the drug is
14:05administered in a bit higher
14:07concentration, it starts binding to, for
14:10instance, the alpha adrenergic
14:12receptors. So, there's a bit of a
14:14crossover effect um
14:17at the higher concentrations.
14:20And that additional binding is one of
14:23the reasons that a drug has greater side
14:25effects with higher doses.
14:27So, does everybody understand Cmax and
14:30the important issues around that
14:32concept?
14:34I've got a follow-up question about
14:37Cmax, but I'm going to hold off on
14:39taking that right now. I think it'll be
14:40probably a little bit better for the two
14:43Cmax questions to be divided.
14:46Uh just remember uh that brings up a
14:49point. Well, as I'm presenting these to
14:51you, obviously what's going to happen is
14:55um as as these are going to be in the uh
14:58quiz,
14:59they won't be in any particular order.
15:01So, you may get the 10th one that I pro-
15:04provide to you today as being number one
15:07in your quiz. Also, the different
15:10choices will be mixed up as well. So,
15:12they're randomized in two separate ways.
15:15Do just be prepared for that one.
15:19Let's go to this next question here. And
15:23uh this one has to do with
15:24pharmacokinetics,
15:26the movement of drugs around the body,
15:29and let's take a look at which of the
15:32following is incorrect. The very first
15:34choice has to do with suppositories
15:36should be placed in the lower portion of
15:38the rectum if they're to avoid the
15:41hepatic first pass.
15:43Remember what the first pass is.
15:46It has to do with the fact that the
15:48blood supply that goes to every cell in
15:50the GIT,
15:52from the middle portion of the esophagus
15:54all the way down to the middle portion
15:56of the rectum, is going to go through
15:59the liver first
16:01before it gets into systemic
16:03circulation. So, if there's any blood
16:05containing any nutrient or poison from
16:08that area, it's going to go into the
16:10liver to
16:12detoxify it, and that's one of our
16:15protective mechanisms.
16:17But, suppose you had a drug that will
16:19get metabolized to an inactive form once
16:22it goes through the liver. Well, that
16:24kind of drug
16:26needs to be delivered by something other
16:28than a pill, for instance.
16:30It needs to find a different pathway,
16:33and some of our drugs are made as
16:35suppositories to do just that, to avoid
16:38the first pass, the hepatic first pass.
16:42And the point of this topic is that if
16:44you place the suppository too high into
16:47the rectum, so let's say that you're
16:50you're placing it right here,
16:52where is it going to go first? It's
16:53going to go straight into the liver,
16:55which is exactly what we're trying to
16:57avoid doing, and therefore
17:00uh yes, suppositories the the statement
17:02suppository should be placed in the
17:04lower portion of the rectum if they're
17:06to to avoid the hepatic first pass is a
17:09correct statement.
17:11The next statement has to do with
17:13lipophilic drugs, and lipophilic drugs
17:15often access a protein carrier molecule
17:19so that they can be carried through the
17:21water-soluble plasma.
17:23Uh lipophilic, of course, means
17:25fat-loving.
17:27So, a fat-loving drugs a a fatty drug is
17:31going to access a protein carrier and
17:34absolutely that statement is correct. If
17:37you put a greasy pan into the dishwater
17:39before
17:41the detergent is in, all of the oil goes
17:44to the top of the water and it just kind
17:45of sits there, doesn't it?
17:47Uh and in the body, we can't use a
17:50detergent. So, we get those fat-soluble
17:53substances, the fat-soluble drugs, the
17:55fat-soluble messenger molecules in the
17:57in the body and so forth. All of those
17:59fat-soluble substances are going to
18:01access a carrier of and protein carrier
18:05molecule.
18:07The The next statement is each drug is
18:09different as to the percent of the drug
18:12that is bound to plasma proteins.
18:14Sometimes it is a high
18:16protein binding and other times it's a
18:18low protein binding.
18:21And I'm going to take this along with
18:23another one of the statements, which is
18:26not actually in your study notes.
18:28Uh so, you have to take this one down.
18:30Only the unbound portion of the drug is
18:33active and it's only the unbound portion
18:36of the drug that can be metabolized.
18:38So, both of those statements are
18:40actually true and let's take a example
18:43used in module one. The example that we
18:46used in module one has to do with this
18:48drug, which is 80% bound to protein.
18:52So, that means 20% of it is free and
18:55that is the 20% that can get into the
18:57cells and be metabolized or it it's uh
19:01can act on receptors or it's free to do
19:03just about anything, right?
19:06But, you know, this other 80% is bound
19:08to proteins.
19:10So, this is where some of the students
19:12actually get unstuck because they think,
19:14well, if it's bound to if 80% is bound
19:16to proteins, that 80% is never really
19:18going to get metabolized, is it? But,
19:20that's totally untrue because as soon
19:23as, you know, this portion a portion of
19:26this 20% over here, this free drug, as
19:28soon as this free drug is bound to a
19:32receptor or something, it it leaves a
19:35little bit of room for something to
19:37disassociate from the protein. So,
19:39another one of the particles of drugs is
19:42going to disassociate from the proteins,
19:44and then it's free to do its job.
19:48So, only the unbound portion of the drug
19:50is going to be metabolized, and that
19:52means that a drug which is highly bound
19:55to proteins may take a bit longer to get
19:58out of the system.
20:00It's kind of waiting around to be
20:01released from the protein carrier
20:03molecules until, you know, the free drug
20:07is actually bound to something.
20:10And finally, the last choice is
20:12obviously going to be false since every
20:14other statement that we've taken already
20:16is true so far. There If there is a high
20:19motility in the GIT, drugs are going to
20:21be absorbed faster because everything is
20:24sped up. And that one is incorrect.
20:28Um
20:29a high motility actually decreases
20:32absorption
20:33because there's an inadequate amount of
20:35time to absorb the drug. Okay, is
20:38everyone happy with that and feels like
20:40they can answer that question correctly?

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