What is pharmacodynamics?

Pharmacodynamics is the study of how drugs produce their biological effects and affect different systems of the body.

A drug is a chemical substance that produces a biological effect when administered to a living organism.

How are drugs classified?

Drugs can be classified by their chemical structure, mechanism of action, or therapeutic use.

What are the different types of drug targets?

The main types of drug targets are ion channels, carrier proteins, enzymes, and receptors.

What is the role of enzymes in pharmacology?

Enzymes are biological catalysts targeted by drugs that can enhance or inhibit their activity, altering cellular metabolism.

What is the difference between agonists and antagonists?

Agonists activate receptors, while antagonists bind to receptors without activation.

How do non-selective drugs work?

Non-selective drugs modify general physiological or chemical processes without a specific target.

What are ion channels?

Ion channels are membrane proteins that allow the passage of ions across cell membranes, important for cellular signaling.

Introduction to Pharmacodynamics | Pharmacology

00:32:36

https://www.youtube.com/watch?v=K-R0LGZYlJY

概要

TLDRThis video lecture introduces pharmacology with a focus on pharmacodynamics, explaining the definitions of drugs, their classifications, and how drugs act on various biological systems. It covers the importance of drug targets, including ion channels, carrier proteins, enzymes, and receptors, detailing how drugs can enhance or inhibit their activity to produce therapeutic effects. Additionally, the lecture examines drug naming conventions and the relationship between drug dosage and effects, emphasizing that the same substance can be a drug or toxin depending on dosage.

収穫

💊 A drug is a chemical substance with biological effects on organisms.
📚 Pharmacodynamics studies how drugs produce effects and interact with the body.
🔍 Drugs can be classified by structure, action, or therapeutic use.
⚗️ Non-selective drugs affect general processes rather than specific targets.
🔑 Key drug targets include ion channels, enzymes, receptors, and carrier proteins.
🧬 Agonists activate receptors, while antagonists block them without activating.
⚖️ Dosage determines whether a substance acts as a therapeutic drug or poison.
🔬 Enzymes can be inhibited or enhanced by drugs, altering metabolic functions.

タイムライン

00:00:00 - 00:05:00
This segment introduces pharmacology, focusing on pharmacodynamics, which examines drug effects on the body. A drug is defined as a chemical substance that causes biological effects, and can be therapeutic or non-therapeutic. Medicines often consist of multiple active ingredients and can be classified based on various criteria. The segment concludes with addressing drug classification and naming systems, including chemical, generic, and proprietary names.
00:05:00 - 00:10:00
The video elaborates on how drugs produce their effects, introducing pharmacodynamics, which focuses on how drugs interact with receptors, enzymes, and other body molecules. Understanding pharmacodynamics is crucial for developing safe drugs and optimizing dosing regimens while minimizing adverse reactions. The segment examines the mechanisms by which drugs modify physiological or biochemical processes to yield biological effects.
00:10:00 - 00:15:00
Various medications exert effects through non-selective interactions without a specific target, such as antacids that neutralize stomach acid chemically or osmotic laxatives that increase water movement in the gastrointestinal tract. Such drugs don’t interact with specific biological targets, emphasizing their mechanism as modifying general physical or chemical processes.
00:15:00 - 00:20:00
Drugs typically target proteins that carry out vital cellular functions, categorized into four groups: ion channels, carrier proteins, enzymes, and receptors. Interaction with these protein targets can enhance, inhibit, or modify their functions, leading to therapeutic outcomes. Each drug's ability to bind and affect specific targets is influenced by the drug and target structure and the interactions formed between them, which will be discussed in further detail later on.
00:20:00 - 00:25:00
Next, the video explores ion channels, integral membrane proteins that modulate ion flow across membranes. Gating of these channels occurs due to physiological signals, differentiated into voltage-gated and ligand-gated channels. Various drugs can impact these ion channels by blocking or enhancing their activity, influencing cellular communication and signaling, and examples such as local anesthetics are presented.
00:25:00 - 00:32:36
The final part of the video examines carrier proteins and their role in transporting molecules. It explains how drugs can affect carrier proteins and consequently influence neurotransmitter reuptake and overall neuronal signaling, using cocaine and fluoxetine as examples. Enzymes are highlighted next, outlining how they can be targeted by drugs to modify metabolic processes, followed by a discussion on drug interactions with receptors—where drugs can act as agonists or antagonists.

ビデオQ&A

What is pharmacodynamics?
Pharmacodynamics is the study of how drugs produce their biological effects and affect different systems of the body.
What is a drug?
A drug is a chemical substance that produces a biological effect when administered to a living organism.
How are drugs classified?
Drugs can be classified by their chemical structure, mechanism of action, or therapeutic use.
What are the different types of drug targets?
The main types of drug targets are ion channels, carrier proteins, enzymes, and receptors.
What is the role of enzymes in pharmacology?
Enzymes are biological catalysts targeted by drugs that can enhance or inhibit their activity, altering cellular metabolism.
What is the difference between agonists and antagonists?
Agonists activate receptors, while antagonists bind to receptors without activation.
How do non-selective drugs work?
Non-selective drugs modify general physiological or chemical processes without a specific target.
What are ion channels?
Ion channels are membrane proteins that allow the passage of ions across cell membranes, important for cellular signaling.

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00:00:00
foreign
00:00:07
introduction to pharmacology and
00:00:10
introduce you to one of the fundamental
00:00:12
concepts which is pharmacodynamics we're
00:00:14
going to break down what a drug is how
00:00:17
drugs produce their effects on the body
00:00:18
and introduce you to the different types
00:00:21
of drug targets and then in later
00:00:23
pharmacodynamics lectures we're going to
00:00:25
expand on these topics all right so
00:00:28
first of all
00:00:29
what is a drug in Pharmacology a drug is
00:00:32
a chemical substance that when
00:00:34
administered to a living organism
00:00:36
produces a biological effect
00:00:38
drugs can be used for therapeutic
00:00:41
purposes to treat diseases or they can
00:00:43
be used for non-therapeutic purposes
00:00:45
such as recreational or experimental use
00:00:49
this also includes the caffeine in your
00:00:51
coffee on an ice latte now and it also
00:00:55
includes experimental tools that are
00:00:57
used in researching diseases or finding
00:01:00
new therapeutic treatments
00:01:02
now medicine is what we usually refer to
00:01:05
as a drug that is used to treat cure or
00:01:08
alleviate a diseases symptoms these are
00:01:12
what we refer to as therapeutic drugs or
00:01:14
therapeutic agents and a lot of
00:01:16
medicines actually contain more than one
00:01:19
active ingredient so there will be a lot
00:01:21
of other things in a therapeutic
00:01:23
formulation so it may contain other
00:01:25
substances such as stabilizers or
00:01:28
solvents for example a brand of
00:01:32
medication used to treat high blood
00:01:33
pressure might contain two different
00:01:35
types of blood pressure lowering drugs
00:01:37
in a single pill okay
00:01:40
another example that we might consider a
00:01:43
drug might be something like a Venom or
00:01:45
a toxin because these substances produce
00:01:48
a biological effect on a living organism
00:01:51
so a poison is a substance that causes a
00:01:53
harmful effect on the body but the thing
00:01:55
is the difference between a drug or
00:01:57
medicine and a poison might be in the
00:02:00
dose if a substance is taken at
00:02:02
therapeutic levels it's very safe and
00:02:05
effective but if taken in overdose it
00:02:08
can lead to dangerous outcomes such as
00:02:10
liver damage and failure and we're going
00:02:13
to break this down in later lectures
00:02:15
where we cover concentration response
00:02:17
relationships and the relationship
00:02:19
between the dose of a drug that's given
00:02:21
and the effect it has so that's the
00:02:23
definition of a drug the question now is
00:02:25
how are drugs classified
00:02:28
drugs can be classified in different
00:02:30
ways based on their chemical structure
00:02:32
mechanism of action which is how the
00:02:34
drug achieves its biological effects
00:02:36
okay so how the drug does what it does
00:02:39
for example going back to lowering blood
00:02:42
pressure how does it lower blood
00:02:44
pressure
00:02:45
another way is based on therapeutic use
00:02:49
so what is the drug designed to do for
00:02:51
example drugs can be classified as
00:02:53
depressants analgesics or antibiotics
00:02:56
based on their effects on the body
00:02:59
okay so then how do you name drugs
00:03:02
because many drugs have multiple
00:03:04
different names there are three main
00:03:06
systems for naming drugs we have
00:03:08
chemical generic and proprietary
00:03:11
chemical names are based on the Drug's
00:03:14
chemical structure and are often complex
00:03:16
and difficult to remember they are
00:03:18
primarily used by chemists and
00:03:21
researchers so it's not really used when
00:03:23
talking about the medications that are
00:03:25
given to patients next are generic names
00:03:27
which are simpler names given to drugs
00:03:30
by Regulatory Agencies ones that have
00:03:33
been approved for use
00:03:35
these names are not owned by any
00:03:37
particular company and are used by
00:03:39
multiple manufacturers
00:03:41
now it's really important for these
00:03:43
approved names to be different from each
00:03:45
other this is to avoid confusion with
00:03:47
other drugs that are already approved
00:03:50
and on the market because we don't want
00:03:52
to prescribe One Drug to a patient who
00:03:54
ends up being given another drug that
00:03:56
has similar sound or spelling to it that
00:03:59
is a completely different effect
00:04:01
and then we have proprietary names also
00:04:04
known as brand names okay so these are
00:04:07
created by drug companies and are used
00:04:09
to Market their products these names are
00:04:11
protected by trademarks and are unique
00:04:13
to a particular product essentially the
00:04:15
naming systems have different
00:04:16
characteristics and uses chemical names
00:04:20
are important for research and
00:04:21
development while generic names are
00:04:24
important for prescribing and dispensing
00:04:26
drugs and proprietary names are
00:04:28
important for marketing and brand
00:04:30
recognition
00:04:32
let's go through an example
00:04:33
so here we have an example for a very
00:04:36
commonly used drug if you're a medicinal
00:04:38
chemist then you will tell you a lot
00:04:40
about the drug but if you aren't then
00:04:42
not really
00:04:43
now if we were to use a generic name or
00:04:46
a trade name most people would be
00:04:48
familiar with the drug the generic name
00:04:50
for this compound is ibuprofen ibuprofen
00:04:53
is the approved name suggested by the
00:04:55
manufacturer and approved by the
00:04:58
regulatory authority to use and describe
00:05:00
the chemical entity if you aren't
00:05:02
familiar with ibuprofen then you are
00:05:04
likely to be familiar with at least one
00:05:06
of the trade or brand names for this
00:05:08
drug
00:05:09
one of the trade names is nurofen
00:05:11
another is Advil it's the same chemical
00:05:14
entity but it is manufactured and
00:05:16
marketed by two different pharmaceutical
00:05:19
companies you can see the differences
00:05:21
between chemical name generic name and
00:05:24
trade name all right so if coveted water
00:05:26
drug is and the different systems that
00:05:28
are used to classify drugs let's now
00:05:30
subtract complexity and start to look at
00:05:32
how drugs produce their effects within
00:05:34
the body we're going to introduce
00:05:36
pharmacodynamics which is the study of
00:05:38
how drugs produce their biological
00:05:40
effects and how drugs will affect the
00:05:42
different systems of the body
00:05:45
it involves understanding the
00:05:47
interactions between drugs and their
00:05:49
target receptors enzymes and other
00:05:51
molecules in the body and how these
00:05:54
interactions lead to changes in cellular
00:05:56
function organ function and ultimately
00:05:58
the overall response of the organism
00:06:02
but before we start breaking this down
00:06:04
why is this important because there's no
00:06:06
point in going through this without
00:06:08
actually asking what our purpose is here
00:06:10
so why is pharmacodynamics important
00:06:13
well because understanding
00:06:16
pharmacodynamics is important for the
00:06:18
development of safe and effective drugs
00:06:20
by studying how drugs interact with the
00:06:23
body we can predict their effects
00:06:25
optimize their thirsting regimenes and
00:06:28
minimize their potential for adverse
00:06:30
reactions okay so then how does a drug
00:06:33
exert its effects on the body
00:06:36
it does this by modifying existing
00:06:39
processes including physiological or
00:06:42
biochemical processes a lot of drugs
00:06:44
exert their effects via specific
00:06:46
chemical interactions or covalent bonds
00:06:48
hydrophobic interactions or
00:06:50
electrostatic okay with particular
00:06:53
molecular targets drug targets can be
00:06:56
proteins enzymes receptors or other
00:06:59
cellular components which will break
00:07:00
down later in this lecture
00:07:03
so the drug is going to bind to the
00:07:05
Target molecule which then modifies the
00:07:08
function of its molecular Target to
00:07:10
produce a biological effect so either
00:07:12
activate or inhibit its function leading
00:07:15
to a physiological response the ability
00:07:17
of a particular drug to bind to its
00:07:19
molecular Target is determined by both
00:07:21
the structure of the drug and the
00:07:23
structure of the molecular Target okay
00:07:25
and the type of interactions formed
00:07:28
between the drug and its Target is
00:07:30
important as well one thing I want to
00:07:32
point out is that there are drugs that
00:07:33
produce their effects on the body by
00:07:35
acting on simple physical or chemical
00:07:37
processes these are called non-selective
00:07:40
interactions or effects what this means
00:07:43
is that these drugs aren't interacting
00:07:45
with a specific molecular Target but
00:07:47
instead are modifying a more General
00:07:49
physical or chemical process let's go
00:07:52
through some examples
00:07:54
a great example are antacids like
00:07:57
calcium carbonate or magnesium hydroxide
00:07:59
which are commonly used for indigestion
00:08:02
these don't have a particular molecular
00:08:04
Target but rather they modify a chemical
00:08:07
process within the body they work by
00:08:10
neutralizing stomach acid through a
00:08:12
simple chemical reaction
00:08:14
so they don't Target any specific
00:08:16
molecule or pathway there are weak base
00:08:19
that acts on the acidic environment of
00:08:21
the stomach because your stomach
00:08:22
produces large amounts of hydrochloric
00:08:25
acid which AIDS in the digestion of food
00:08:28
so the hydrochloric acid in the stomach
00:08:30
will react directly with the antacid and
00:08:33
therefore the acid will become
00:08:35
neutralized so you will end up with a
00:08:36
reduction in the acidity of the stomach
00:08:39
that's pretty cool okay so there's our
00:08:41
antacids another example of a type of
00:08:44
drug that exerts is effect by modifying
00:08:47
a non-selective process
00:08:49
are asthmatic agents an example is
00:08:52
osmotic laxatives which you may know are
00:08:55
useful the treatment of constipation
00:08:57
okay but they're also used for the
00:08:59
preparation of particular GI procedures
00:09:02
such as a colonoscopy so what these
00:09:04
osmotic laxatives do is they're going to
00:09:06
draw water into the colon which
00:09:08
increases the bulk and softness of stool
00:09:11
promoting bowel movements this effect is
00:09:14
not due to any specific interaction with
00:09:17
a drug Target but rather to the physical
00:09:19
process of water movement okay so these
00:09:23
laxatives contain molecules that are
00:09:25
difficult for the GI tract to absorb so
00:09:28
there's going to be a higher
00:09:29
concentration of these molecules that
00:09:31
stay within the GI tract so there's
00:09:33
going to be an increase in soil
00:09:35
concentration inside the GI tract which
00:09:38
then stimulates osmotic activity because
00:09:40
water follows solute so what happens is
00:09:43
it's going to cause water to move from
00:09:45
the gut capillaries into the inside of
00:09:48
the GI tract okay so that's how
00:09:50
laxatives work
00:09:52
both antacids and osmotic agents in this
00:09:55
case osmotic laxatives are examples of
00:09:57
drugs that have non-selective effects on
00:10:00
the body so in summary some drugs can
00:10:02
exert their effects through
00:10:03
non-selective interactions with simple
00:10:06
chemical and or physical processes
00:10:08
without targeting any specific molecule
00:10:10
or pathway all right so it's good to be
00:10:13
aware of these types of drugs
00:10:16
let's now move on and break down the
00:10:19
different types of drug targets and how
00:10:20
different drugs affect these targets
00:10:25
all right now
00:10:28
the majority of drugs produce their
00:10:30
effects via selective interactions with
00:10:32
proteins so they will bind to a protein
00:10:35
and alter the function of that protein
00:10:39
we refer to the site where a drug binds
00:10:42
to exert its action as a molecular
00:10:44
Target although protein molecules aren't
00:10:47
always the molecular targets of drugs
00:10:49
they just make up the majority of them
00:10:51
and we can divide these protein targets
00:10:54
for drug action into four main groups we
00:10:57
have iron channels carrier proteins
00:11:00
enzymes and receptors each of these
00:11:03
targets play plays an important role in
00:11:05
cellular function and can be targeted by
00:11:08
drugs to achieve therapeutic effects
00:11:10
so again drugs can enhance the activity
00:11:14
of a protein inhibited or modify its
00:11:17
normal function so let's go through each
00:11:20
of these four different types of
00:11:21
proteins and use examples of how drugs
00:11:24
can act on that type of Target starting
00:11:26
with iron channels ion channels are
00:11:29
membrane proteins that allow the passage
00:11:31
of ions such as sodium potassium and
00:11:34
calcium across cell membranes so they
00:11:37
are formed by a single protein or a
00:11:39
group of proteins that are embedded
00:11:41
within the plasma membrane these
00:11:44
channels are really important in
00:11:46
cellular cell communication between
00:11:47
excitable cells so neurons muscles even
00:11:51
cells that are involved in secretion
00:11:54
so when iron channels are open they're
00:11:57
going to create an open pore or passage
00:11:59
between the extracellular fluid and the
00:12:02
inside of the cell or intracellular
00:12:04
fluid and they are characterized by
00:12:06
having specificity or selectivity for
00:12:09
different types of ions so for example
00:12:11
there are channels that are selective
00:12:14
for sodium ions potassium ions or
00:12:16
calcium ions and the channel name will
00:12:19
depend on the selection the different
00:12:21
types of ions so a channel that is
00:12:23
selective or only allows sodium to pass
00:12:26
will be referred to as the sodium
00:12:28
Channel and what determines whether an
00:12:31
ion can move through the open pore is
00:12:33
influenced by the charge of the iron as
00:12:35
well as the size of the molecule okay
00:12:38
now
00:12:40
ion channels can exist in different
00:12:42
types of States so they can either be in
00:12:45
an open or closed State and these
00:12:47
channels are regulated to make sure that
00:12:50
they are open or closed in response to
00:12:53
different types of physiological signals
00:12:55
because cells such as neurons and muscle
00:12:57
cells rely on ION channels to create the
00:13:00
appropriate signals that allow those
00:13:02
cell types to do their job effectively
00:13:05
okay so we want to open or close these
00:13:08
channels appropriately
00:13:10
so this is known as gating of channels
00:13:13
or Channel gating so the opening or
00:13:16
closing of ion channels is determined by
00:13:19
Channel gaming okay iron Channel gating
00:13:22
can be regulated by various types of
00:13:24
stimuli but we're going to go through
00:13:26
two examples voltage-gated channels and
00:13:29
ligand-gated channels starting with
00:13:31
voltage-k channels these are regulated
00:13:34
by changes in the cell's membrane
00:13:36
potential so think your neurons and your
00:13:38
muscle cells
00:13:40
remember that membrane potential refers
00:13:43
to the difference in electrical charge
00:13:45
between the inside and the outside of
00:13:48
the cell resting membrane potential is
00:13:50
the voltage difference across the cell
00:13:52
membrane when cells are at rest
00:13:56
so with voltage-geated channels in this
00:13:59
case we have sodium channels these have
00:14:02
two gates there's an activation gate and
00:14:04
an inactivation gate so the inactivation
00:14:07
gate here can be described as a ball and
00:14:10
chain-like structure okay so these
00:14:12
channels have three states or
00:14:14
conformations
00:14:16
first it can be closed but capable of
00:14:19
opening okay so the inactivation gate
00:14:21
here is open because the ball is just
00:14:23
hanging free it can be completely open
00:14:25
and activated so both gates are open or
00:14:28
it can be closed and not capable of
00:14:31
opening it's inactivated this is the
00:14:33
inactivation state
00:14:35
so voltage-gated ion channels will be
00:14:38
influenced by whether they're in an open
00:14:40
state or a closed State okay so some of
00:14:43
these channels will be stimulated to
00:14:45
open will be stimulated to open by
00:14:48
depolarization or hyperpolarization any
00:14:51
changes in the membrane potential
00:14:53
determine whether the channel is open or
00:14:55
closed alright that's voltage-gated ion
00:14:58
channels
00:15:00
the other type are ligand gated channels
00:15:03
these are also called ionotropic
00:15:06
receptors so these are large protein
00:15:09
complexes these are iron channels that
00:15:12
open directly in response to ligand
00:15:14
binding so they are regulated by The
00:15:16
Binding of chemical ligands a great
00:15:19
example are neurotransmitters that are
00:15:21
involved in synaptic transmission once a
00:15:23
neurotransmitter binds this will cause
00:15:26
the child to change shape and it's going
00:15:28
to open up allowing ions from the
00:15:30
extracellular fluid to enter
00:15:32
so here we have the nicotinic
00:15:35
acetylcholine receptor and right now
00:15:37
this channel is in its close state so
00:15:39
it's not allowing any ions to pass
00:15:41
through the channel now when the ligand
00:15:44
acetylcholine binds to the channel it
00:15:46
will change the confirmation of the
00:15:48
channel and earthena and it's going to
00:15:51
allow ions in this case sodium ions to
00:15:53
flow into the cell and down its
00:15:55
concentration gradient okay so these are
00:15:57
the two main types of gating channels
00:15:59
voltage gain and ligand gating there are
00:16:02
also some other types of buying channels
00:16:05
that are regulated by other types of
00:16:07
physical changes such as stretch
00:16:09
sensitive channels and temperature
00:16:11
sensitive channels okay so these are
00:16:13
just the two main types
00:16:15
okay
00:16:16
now
00:16:18
there are multiple different ways in
00:16:20
which drugs can affect the activity of
00:16:23
iron channels so
00:16:25
drugs that Target iron channels can
00:16:28
either block or enhance their activity
00:16:30
altering the flow of ions and impacting
00:16:33
cellular signaling and communication
00:16:36
so some drugs will directly alter ion
00:16:39
channels by binding to different sites
00:16:41
on the Ion channel modifying the state
00:16:44
of the channel okay so a drug can bind
00:16:46
to the channel in such a way that it
00:16:49
prevents the ions from moving through
00:16:51
the channel examples of drugs that
00:16:53
Target ion channels include local
00:16:55
anesthetics which block sodium channels
00:16:57
and reduce pain sensation but let's look
00:17:00
at a more specific example by looking at
00:17:03
drugs that affect voltage-gated sodium
00:17:05
channels
00:17:07
if you've seen the action potentials
00:17:09
lecture who talked about how important
00:17:11
these channels are in generating Action
00:17:13
potentials in cells like neurons and
00:17:15
muscle cells these sodium channels are
00:17:18
usually closed in the resting state and
00:17:20
with the neuron depolarizes that
00:17:23
triggers the opening of these channels
00:17:25
What happens when the Childs are open
00:17:27
it's going to allow sodium ions to flow
00:17:30
into the cell which allows for the
00:17:32
continuation of action potential of the
00:17:34
action potential
00:17:36
so one example of a drug that directly
00:17:39
affects voltage-gated sodium channels is
00:17:41
tetradotoxin
00:17:43
it's drug directly blocks the channel
00:17:45
here so this is a neurotoxin that's
00:17:47
found in a range of different Marine
00:17:49
creatures and causes inhibition of
00:17:51
neurotransmission which leads to a loss
00:17:54
of sensation and in higher
00:17:55
concentrations paralysis so tetradotoxin
00:17:59
blocks these channels which then inhibit
00:18:01
Island movement through the channel
00:18:03
directly sorry can't pass through ions
00:18:06
can't pass through the channel the thing
00:18:07
is it doesn't matter whether the channel
00:18:09
is in the urban State the inactivated
00:18:11
State or the closed State the actions of
00:18:14
tetradotoxin are the same so its action
00:18:16
is independent of the state of the
00:18:18
channel
00:18:19
now there are also drugs that affect
00:18:22
voltage-gated sodium channels and are
00:18:24
dependent on the channel state for their
00:18:27
action an example is lignocaine which is
00:18:31
a type of anesthesia that works by
00:18:33
binding to open or recently open
00:18:35
channels in the nerves so when neurons
00:18:38
are firing frequently there are more
00:18:41
open or inactivated channels or in
00:18:43
active channels for lignicane to bind to
00:18:46
in those areas this is important because
00:18:48
it allows for more targeted anesthesia
00:18:51
in these areas with more nerve activity
00:18:54
which is especially useful since Sensory
00:18:57
neurons increase their firing rate with
00:18:59
the intensity of the stimuli causing
00:19:01
them to fire so lignocaine's
00:19:04
interactions with these channels is used
00:19:06
dependent meaning it is more effective
00:19:09
in areas with higher nerve activity okay
00:19:12
so essentially there are different ways
00:19:15
drugs can interact with ion channels
00:19:18
either directly such as with
00:19:19
tetrodotoxin or dependent on their
00:19:21
Channel State like lignitine all right
00:19:24
that's ion channels
00:19:27
let's now move on to the second type of
00:19:29
protein Target for drug action which is
00:19:32
another type of transport protein
00:19:33
carrier proteins carrier proteins are
00:19:36
membrane proteins that transport
00:19:38
molecules across cell membranes
00:19:41
here's the thing
00:19:42
they don't form an open Channel or pore
00:19:45
between the inside and outside of the
00:19:47
cell what carrier proteins do is they
00:19:51
take different conformation shape okay
00:19:53
and shuttle the molecule from one side
00:19:56
to the other this process involves a
00:19:59
series of changes in the structure of
00:20:01
the carrier protein that influence its
00:20:03
orientation towards the inside or
00:20:05
outside of the cell as well as the
00:20:07
ability of different molecules to bind
00:20:09
to it
00:20:10
so specifically when a soil molecule
00:20:13
needs to be transported across the
00:20:15
membrane it binds to the carrier protein
00:20:18
causing a conformational change so here
00:20:21
we have the molecule it's cured as
00:20:24
molecule that needs to be transported
00:20:26
and the gate to the inside of the cell
00:20:28
is closed but open to the outside of the
00:20:31
cell and so this is going to flip okay
00:20:33
this flips the carrier protein so that
00:20:36
it is no longer open to the outside of
00:20:38
the cell but now open to the inside of
00:20:40
the cell so the gate is close to the
00:20:43
outside so there's a conformational
00:20:44
change here okay the shape is changing
00:20:48
so this change in conformation allows
00:20:51
the solid molecule to move across the
00:20:53
membrane and then eventually
00:20:54
dissociating from the carrier protein
00:20:57
inside the cell it's pretty cool right
00:20:59
now one key feature of carrier proteins
00:21:02
is that they're never open to both sides
00:21:05
of the membrane at the same time
00:21:07
this is because the solid molecule must
00:21:10
bind to a specific site on the protein
00:21:12
channel to be transported and this also
00:21:15
means that the carrier proteins can be
00:21:17
subject to competition and potential
00:21:19
saturation of the transport mechanism
00:21:22
okay so the binding Affinity of the
00:21:25
solute to the carrier protein is also
00:21:27
affected by conformational changes in
00:21:30
that protein structure this means that
00:21:33
the ability of different molecules to
00:21:35
bind to a specific carrier protein can
00:21:38
vary all right
00:21:39
now
00:21:41
carrier proteins can be classified in
00:21:43
different ways one method involves
00:21:46
characterizing them by the type of
00:21:48
molecule they transport such as sodium
00:21:50
glucose or potassium
00:21:53
and there are also several types of
00:21:55
carrier proteins including uniport
00:21:57
Transporters that can only transport a
00:22:00
single molecule and co-transporters that
00:22:03
can carry multiple types of molecules
00:22:06
simultaneously or at the same time such
00:22:08
as sodium glucose protransporters or
00:22:11
sodium potassium co-transporters okay if
00:22:14
they're co-transporters move the
00:22:16
molecules in the same direction across
00:22:18
the membrane they are referred to as
00:22:19
simple carriers however if the transport
00:22:23
protein moves molecules in different
00:22:25
directions they are known as antipod
00:22:28
carriers
00:22:29
so that's one method another method of
00:22:32
characterizing carrier proteins is based
00:22:35
on the energy source that powers the
00:22:37
transport passive transport or
00:22:40
facilitated diffusion occurs when
00:22:42
molecules move down their concentration
00:22:44
gradient without the need for external
00:22:46
energy it doesn't require any energy
00:22:48
whereas active transport involves the
00:22:50
movement of molecules against their
00:22:52
concentration gradient which requires
00:22:54
external energy such as ATP okay
00:22:58
so now that we've established what
00:23:00
carrier proteins are let's look at some
00:23:02
examples let's look at how drugs can
00:23:04
influence this process can influence
00:23:07
carrier proteins
00:23:09
so drugs that Target carrier proteins
00:23:11
can interfere with their ability to
00:23:13
transport molecules altering cellular
00:23:16
metabolism and function
00:23:18
we're still looking at neurotransmission
00:23:19
here
00:23:21
so we have the presynaptic terminal and
00:23:23
the person optic cell and we have a per
00:23:26
synaptic receptor right here and what a
00:23:29
substance binds you will produce a
00:23:31
response in the per synaptic cell okay
00:23:34
so remember what happens when an action
00:23:36
potential reaches the axon terminal
00:23:39
it's going to stimulate the
00:23:40
voltage-gated calcium channels to open
00:23:42
and calcium ions are going to flow into
00:23:45
the synaptic knob where calcium triggers
00:23:47
the release of neurotransmitters from
00:23:50
the synaptic vesicles here which contain
00:23:52
dopamine serotonin and noradrenaline
00:23:55
so here we have neurotransmitters being
00:23:58
released at the synapse where they can
00:24:00
interact with a receptors to produce a
00:24:03
response
00:24:04
but what we're truly focused on here is
00:24:07
the reuptake process
00:24:09
these neurotransmitters are terminated
00:24:11
their actions are terminated when they
00:24:13
are removed from the synapse okay so
00:24:16
generally the removal of the
00:24:18
neurotransmitter occurs via reuptake
00:24:20
into the presynaptic neuron via a
00:24:23
carrier protein through the process of
00:24:25
facilitated diffusion okay so reuptake
00:24:29
is when the neurotransmitters are taken
00:24:31
back up into the presynaptic neuron
00:24:34
after they have been released into the
00:24:36
synapse now why is this process
00:24:38
important why are we talking about this
00:24:40
because reuptake helps helps the
00:24:43
regulation it helps to regulate the
00:24:46
duration and strength of neuronal
00:24:48
signaling it's important to the overall
00:24:51
functioning of the nervous system
00:24:53
and there are several different drugs
00:24:55
that can interfere with this process and
00:24:58
they do Serve by blocking the carrier
00:25:00
proteins okay because if you block the
00:25:02
carrier proteins what's going to happen
00:25:04
you will get less of the
00:25:06
neurotransmitter that gets taken back up
00:25:08
into the presynaptic neuron and what
00:25:10
happens okay so when this happens what
00:25:13
do we do it means you've got more
00:25:15
neurotransmitter present in the synapse
00:25:17
and therefore you're going to enhance
00:25:19
the actions of that neurotransmitter
00:25:21
because remember the actions of the
00:25:24
neurotransmitter are early terminated
00:25:25
when they are removed from the synapse
00:25:28
so if we're blocking the re-uptake
00:25:29
protein okay this carrier protein here
00:25:32
we're going to be leaving
00:25:33
neurotransmitters in the synapse that
00:25:36
therefore enhancing their activity so
00:25:38
let's go through two examples including
00:25:40
cocaine and Fluoxetine
00:25:42
so first up cocaine so what cocaine does
00:25:46
is it blocks the carrier proteins that
00:25:48
are responsible for neurotransmitters
00:25:50
such as dopamine and norepinephrine so
00:25:53
then it has a stimulatory effect on
00:25:56
those neurotransmitters because these
00:25:58
transmitters are going to stay in the
00:26:00
synapse for longer causing Euphoria and
00:26:03
all the other effects that cocaine has
00:26:05
so there's going to be a buildup of
00:26:06
these neurotransmitters in the synapse
00:26:09
okay so that's cocaine on the other hand
00:26:11
fluoxetine is an example of a drug that
00:26:13
is more selective for individual carrier
00:26:15
protein mechanisms what fluoxetine does
00:26:18
is blocks the carrier protein that is
00:26:21
responsible for the reuptake of
00:26:22
Serotonin into the nervous system this
00:26:25
is an example of a selective serotonin
00:26:28
react take with okay which blocks the
00:26:31
reuptake of Serotonin and increases its
00:26:34
availability these drugs are one of the
00:26:36
most commonly used in the treatment of
00:26:38
depression okay so these are the
00:26:41
different ways in which drugs can
00:26:42
interfere with carrier proteins to
00:26:44
influence the actions of
00:26:46
neurotransmitters
00:26:48
let's now move on to the next type of
00:26:50
drug targets enzymes
00:26:52
so recall that enzymes are biological
00:26:55
catalysts they speed up a reaction
00:26:57
without being consumed other reaction
00:26:59
and most enzymes are proteins enzymes
00:27:02
are important for a whole range of
00:27:04
biological processes their activity
00:27:07
depends on their protein conformation
00:27:09
including primary secondary tertiary and
00:27:12
quaternary protein structures if an
00:27:15
enzyme is denatured it's catalytic
00:27:17
activity is gone okay so drugs that
00:27:19
Target enzymes can either enhance or
00:27:21
inhibit their activity
00:27:23
altering cellular metabolism
00:27:25
neurotransmission and function let's go
00:27:27
through an example of a drug called near
00:27:29
stigma that inhibits an enzyme involved
00:27:32
in neurotransmission
00:27:34
so you may have heard of acetylcholine
00:27:36
okay so acetylcholine is a
00:27:38
neurotransmitter that's important in the
00:27:40
peripheral and central nervous system
00:27:42
and synthesize from acetyl-coa and
00:27:45
choline catalyzed by choline acetyl
00:27:48
transferase now the actions of
00:27:50
acetylcholine are terminated when
00:27:53
acetylcholine is broken down similar to
00:27:55
what we've just spoken about
00:27:57
and it's broken down by an enzyme called
00:28:00
acetylcholinesterase that is found in
00:28:02
nerve terminals where acetylcholine is
00:28:05
released okay so when acetylcholine is
00:28:07
released it can then diffuse across the
00:28:08
synapse and bind to per synaptic
00:28:11
receptor proteins so then this
00:28:13
acetylcholine receptor opens up allowing
00:28:16
ions to flow inside so going back to
00:28:19
acetylcholinesterase it breaks down the
00:28:21
acetylcholine into choline and acetate
00:28:24
in activating that neurotransmitter
00:28:26
because the actions of a
00:28:27
neurotransmitter is terminated when it's
00:28:29
removed from the synapse so what we're
00:28:32
doing here is we're going to break it
00:28:33
down to choline and acetate there are
00:28:37
several different drugs that can Target
00:28:38
inhibit this acetylcholinesterase okay
00:28:41
so different drugs can inhibit
00:28:43
acetylcholinesterase and one example of
00:28:46
a drug that inhibits
00:28:47
acetylcholinesterase in a competitive or
00:28:50
reversible manner is near stigma okay so
00:28:53
neostigmine binds to and inhibits
00:28:56
acetylcholinesterase so then what
00:28:58
happens when we inhibit the activity of
00:29:00
this enzyme well now we can't break down
00:29:02
acetylcholine and so we're going to end
00:29:05
up with increased levels of
00:29:07
acetylcholine at the synapse so
00:29:09
neostigmine is a drug that is involved
00:29:11
in the treatment of myasthenia gravis
00:29:13
which is our neuromuscular disease
00:29:15
that's characterized by a failure of
00:29:17
transmission at the neuromuscular
00:29:19
Junction okay and the main
00:29:21
neurotransmitter at the junction is
00:29:23
acetylcholine so if we step back and
00:29:25
think about that for a second
00:29:27
by preventing the breakdown of
00:29:29
acetylcholine we're going to increase
00:29:31
the levels of acetylcholine at the
00:29:33
neuromuscular Junction and what's this
00:29:35
going to do it's going to enhance
00:29:37
neuromuscular transmission okay so
00:29:40
that's near stigma and we mentioned that
00:29:42
this drug can bind to and inhibit this
00:29:44
enzyme reversibly but there are also
00:29:47
drugs that do this irreversibly which
00:29:49
means we can't take it back okay and
00:29:51
there's a name for this family of
00:29:53
molecules that irreversibly inhibits
00:29:55
this enzyme here they are known as
00:29:58
organophosphates all right so this is an
00:30:01
example of how enzymes can be the cause
00:30:03
of drug action
00:30:05
for either enhancing or inhibiting the
00:30:07
activity altering its function okay
00:30:11
the last type we're going to look at are
00:30:15
receptors so these bad boys recognize
00:30:18
and respond to the different types of
00:30:20
chemical messages that our body uses to
00:30:22
communicate they bind to specific
00:30:24
signaling molecules such as hormones
00:30:26
neurotransmitters and cytokines and
00:30:29
transmit signals into cells
00:30:31
so the effect of neurotransmitters
00:30:35
hormones and other chemical mediators
00:30:37
are controlled by receptors so drugs
00:30:40
that Target receptors again can either
00:30:42
enhance or block their activity altering
00:30:45
cellular signaling and function
00:30:48
and one common mechanism for influencing
00:30:51
a recipe is through an activating drug
00:30:53
which is known as an Agonist an Agonist
00:30:56
is a drug that binds to and activates a
00:30:59
receptor we're going to talk about this
00:31:00
in more detail in further
00:31:02
pharmacodynamic structure okay but just
00:31:04
know an Agonist is a drug that binds to
00:31:07
and activates a receptor whereas an
00:31:09
antagonist is a drug that binds to the
00:31:11
receptor but does not cause activation
00:31:14
it combines to it but it doesn't
00:31:15
activate it so when an Agonist binds to
00:31:17
a receptor it's going to activate a
00:31:19
signaling mechanism within the cell and
00:31:21
which have a signaling mechanism is
00:31:23
activated will determine the cellulite
00:31:25
effects examples of drugs that Target
00:31:27
receptors include beta Agonist which
00:31:30
activate beta adrenergic receptors and
00:31:32
increase heart rate and Airway dilation
00:31:35
and we also have antihistamines which
00:31:37
block histamine receptors and reduce
00:31:39
allergic symptoms we'll break down the
00:31:41
four main types of receptors in another
00:31:43
lecture but for now understand that
00:31:45
receptors are a very diverse group of
00:31:47
proteins and can mediate a whole range
00:31:50
of different types of effects in the
00:31:52
body from quick responses like
00:31:54
neurotransmission to much slower
00:31:56
processes that are related to growth and
00:31:58
development okay
00:32:00
all right so we've covered a lot in this
00:32:03
lecture so to summarize it okay drugs
00:32:06
can affect the four main types of
00:32:07
molecular targets for drug action we
00:32:10
have iron channels carrier proteins
00:32:12
enzymes and receptors by either
00:32:14
enhancing or inhibiting their activity
00:32:17
or altering cellular signaling and
00:32:19
function to achieve therapeutic effects
00:32:21
thank you for watching this video make
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タグ

Pharmacology
Pharmacodynamics
Drug Classification
Drug Targets
Ion Channels
Carrier Proteins
Enzymes
Receptors
Drug Interaction
Therapeutic Effect