How Do Nitrates Work? (Nitroglycerin)
Summary
TLDRThis video explains how nitrates work, focusing on their role in treating angina pectoris, a type of chest pain caused by an imbalance between oxygen supply and demand in the heart. It discusses different types of nitrates, including nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate, their mechanisms, dosing, and when they are used for acute versus chronic angina. The video also covers potential side effects like headaches and dizziness, drug interactions, particularly with PDE5 inhibitors, and the importance of a nitrate-free interval to prevent tolerance build-up.
Takeaways
- 💡 Angina pectoris is chest pain caused by an imbalance between the oxygen supply and demand of the heart.
- 🏃 Running increases the oxygen demand for the heart and the entire body, which can lead to ischemia if the supply can't meet the demand.
- 💊 Nitrates, such as nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate, help alleviate chest pain by increasing the oxygen supply to the heart.
- 🌐 Nitrates work by dilating veins, which allows more blood and oxygen to flow into the heart, reducing the preload.
- 💨 Nitroglycerin is used for acute angina and acts quickly when dissolved under the tongue, providing fast relief.
- 🛡 Chronic angina is managed with longer-acting nitrates like isosorbide mononitrate and dinitrate, which require a 12-hour nitrate-free interval to prevent tolerance.
- 🚨 Patients should call emergency services if chest pain persists after the first dose of nitroglycerin, indicating a severe and ongoing issue.
- 💡 Nitrates release nitric oxide, which aids in the formation of cyclic GMP, leading to the relaxation of smooth muscles and vasodilation.
- 🚫 Nitrates are contraindicated with PDE5 inhibitors due to the risk of severe hypotension caused by the combined vasodilatory effects.
- 🤒 Common side effects of nitrates include headache, flushing, dizziness, and orthostatic hypotension, all related to vasodilation.
- 📚 Dosage for acute angina with nitroglycerin is 0.3 to 0.6 milligrams sublingual every 5 minutes, up to three times, while chronic preventative dosing varies for isosorbide mononitrate and dinitrate.
Q & A
What does 'angina pectoris' refer to?
-Angina pectoris refers to chest pain caused by an imbalance between the oxygen supply and demand of the heart.
Why does ischemia occur in the heart?
-Ischemia occurs when there is not enough oxygen supply to meet the oxygen demand of the heart, potentially causing damage to the heart muscle.
What is the primary function of nitrates in treating angina?
-Nitrates primarily function by dilating the veins leading to the heart, increasing the oxygen supply to the heart and thereby relieving chest pain.
How do nitrates increase the oxygen supply to the heart?
-Nitrates increase the oxygen supply to the heart by causing vasodilation, which allows more blood and oxygen to flow into the heart.
What is the role of nitric oxide in the action of nitrates?
-Nitric oxide, released by nitrates, facilitates the formation of cyclic GMP, which leads to the relaxation of smooth muscles and results in vasodilation.
What are the two types of angina that nitrates can be used for?
-Nitrates can be used for acute angina, which requires immediate relief, and chronic angina, which is a preventative measure.
Which brand name is associated with nitroglycerin for acute angina treatment?
-Nitrostat is the brand name associated with nitroglycerin, used for treating acute angina.
What is the importance of a 12-hour nitrate-free interval when using isosorbide mononitrate or dinitrate?
-A 12-hour nitrate-free interval is necessary to prevent the development of tolerance, ensuring the effectiveness of these long-acting nitrates.
Why are nitrates contraindicated with PDE5 inhibitors?
-Nitrates are contraindicated with PDE5 inhibitors because their combined use can lead to severe hypotension due to the increased vasodilation effect caused by the inhibition of cyclic GMP breakdown.
What are some common side effects associated with nitrate use?
-Common side effects of nitrate use include headache, flushing, dizziness, and orthostatic hypotension, all of which are related to vasodilation.
Outlines
💡 Understanding Nitrates and Angina Pectoris
This paragraph introduces the topic of nitrates and their role in treating angina pectoris, a condition characterized by chest pain due to an imbalance between oxygen supply and demand in the heart. It explains the concept of ischemia, which is the lack of oxygen to the heart, and how it leads to angina. The paragraph also introduces the three common types of nitrates: nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate, and their function in increasing oxygen supply to the heart by dilating veins, thereby reducing the preload.
🚑 Acute and Chronic Angina Treatment with Nitrates
This section discusses the practical application of nitrates in treating both acute and chronic angina. Acute angina is addressed with nitroglycerin, a fast-acting medication taken sublingually for immediate relief. Chronic angina is managed with longer-acting nitrates, isosorbide mononitrate and isosorbide dinitrate, which require a 12-hour nitrate-free interval to prevent tolerance. The paragraph also covers the dosing for these medications and emphasizes the importance of proper patient counseling on their use.
💊 Nitrate Side Effects and Drug Interactions
This paragraph delves into the side effects associated with nitrate use, such as headache, flushing, dizziness, and orthostatic hypotension, all of which are linked to vasodilation. It also highlights a critical drug interaction between nitrates and PDE5 inhibitors, commonly used for erectile dysfunction, which can lead to severe hypotension due to the combined vasodilatory effects. The explanation includes a brief overview of the biochemical process involving nitric oxide and cyclic GMP that leads to vasodilation.
📚 Recap and Quiz on Nitrates and Their Applications
The final paragraph provides a summary of the key points discussed in the video script, including the definition of ischemia, the mechanism of action of nitrates, the types of nitrates used for acute and chronic angina, and the importance of a nitrate-free interval. It also outlines the side effects and the significant drug interaction with PDE5 inhibitors. The paragraph concludes with a short quiz to reinforce the viewer's understanding of the material presented.
Mindmap
Keywords
💡Nitrates
💡Angina Pectoris
💡Ischemia
💡Vasodilation
💡Nitroglycerin
💡Isosorbide Mononitrate and Isosorbide Dinitrate
💡Cyclic GMP (cGMP)
💡Orthostatic Hypotension
💡PDE5 Inhibitors
💡Tolerance
Highlights
Introduction to the topic of nitrates and their pharmacological role in treating chest pain.
Definition of angina pectoris as chest pain caused by an imbalance of oxygen supply and demand in the heart.
Explanation of ischemia as a condition of insufficient oxygen supply to the heart, leading to potential damage.
Overview of the three common nitrates: nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate.
Mechanism of action of nitrates in dilating veins to increase oxygen supply to the heart.
Description of nitroglycerin's role in treating acute angina by providing rapid relief.
The importance of a 12-hour nitrate-free interval for chronic nitrate medications to prevent tolerance.
Brand names and dosing information for nitroglycerin (Nitrostat) and isosorbide mononitrate/ dinitrate.
Instructions for patients on using nitroglycerin sublingually and the necessity to call emergency services if chest pain persists.
Side effects of nitrates including headache, flushing, dizziness, and orthostatic hypotension.
Contraindication of nitrates with PDE5 inhibitors due to the risk of severe hypotension.
Explanation of the biochemical process involving nitric oxide and cyclic GMP leading to vasodilation.
Importance of proper administration of chronic nitrate medications to avoid improper dosing and potential health risks.
Differentiation between acute and chronic angina treatment approaches and their respective nitrate medications.
Summary of the video's key points on nitrates, their use in treating angina, and associated side effects and drug interactions.
Introduction of a short quiz to test viewers' understanding of the presented information on nitrates.
Transcripts
hello and welcome to another drug drug
episode and today we'll talk about
nitrates and how they work
plus some pharmacology let's get right
into it
so here's a breakdown of everything in
this video there will be time stamps
down below
and a short quiz at the end to see what
we retained
so to understand how nitrates work we
need a quick overview
and to do that we kind of need to look
at the heart
so the first thing we need to know is
something called
angina pectoris which literally means
chest pain and here we could see a
patient holding their heart
and they're having that chest pain and
that's actually caused by the heart
so let's take a look how so here we have
the heart
and essentially there's a balance
between the oxygen supplied
and the oxygen demanded by the heart
because remember
the heart is a muscle so as it keeps
pumping
and if it pumps harder and faster it's
going to need more and more
oxygen so the issue with angina pectoris
is there is a imbalance
of oxygen supply and oxygen demand
meaning the heart is demanding more
oxygen
than it can actually pump to itself
so let's take running for example you
know if we run obviously our heart rate
goes up
and the demand for oxygen for not only
the heart but essentially the whole body
will go up so the issue
is that the oxygen supply isn't getting
to the heart
fast enough or efficiently enough
and when this happens when there is less
oxygen supply and more oxygen
demand right then we have something
called
ischemia which literally means not
enough oxygen and that could damage our
heart
but the heart knows that it's not having
enough oxygen
and then that's when we'll see patients
have angina pectoris because the heart
is literally hurting because of the lack
of oxygen
and they feel that chest pain so now
that we know a little bit about the back
story of
having chest pains let's talk about
nitrates
and how they work so here we have our
first three nitrates these are the most
common
we have something called nitroglycerin
which is the most common
and then we have longer acting nitrates
which we'll talk about in detail later
called isosorbide mononitrate and
isosorbide dinitrate so since we said
the
issue with angina that chest pain
was the lack of oxygen supply
to oxygen demand what we need to do
is increase the oxygen supply right
if we need more oxygen we got to figure
out a way
to allow the heart to have more oxygen
and in a nutshell
that's what nitrates do they allow more
oxygen to go to the heart so here we see
we have
veins and arteries that lead
to and from the heart and remember
oxygen is carried
through blood cells right your blood
and your hemoglobin inside the actual
blood cell
holds oxygen so the way nitrates work is
they actually
dilate the veins leading to the heart
and this is also called preload meaning
before
the blood supply and if we increase the
preload
if we dilate those veins
we allow more blood to easily flow in
with
oxygen so now we know that nitrates
dilate the veins allowing
more blood and more oxygen to reach the
heart
so how does that actually happen right
so if we have a patient like this one
here
and we give them nitroglycerin
essentially what happens is
that medication gets absorbed and
nitric oxide which is part of the
medication
is released so that nitric oxide
in our body will allow the formation of
something called
cyclic gmp or abbreviated as
c gmp and cyclic gmp in our body
allows for smooth muscles to relax
and smooth muscles are like our veins
and arteries now when the smooth muscles
relax we get that
vasodilation and because of that
we see an improved blood supply
and we have an increased oxygen supply
to meet the demand
so essentially again we're just
increasing that
supply to the heart so that it has
efficient
oxygen so when do we actually use these
nitrates
well there's two realistic possibilities
in our patients
so we have something called acute angina
meaning they have
severe chest pain and we need to treat
their chest pain right now
and we use the nitroglycerin for that
it's very quick acting
it dissolves under the tongue and it
gives very fast relief
and on the other side we have chronic
angina
and here we use our other preventative
measures
we use the isosorbide mononitrate or
dinitrate
and again this is more of a preventative
cause these last a lot longer
these last for 12 hours and the reason a
patient may need these drugs
is that their blood vessels may narrow
for example a patient can have coronary
artery disease we could have plaque
buildup in the veins leading less and
less blood flow
to the heart which could lead to the
ischemia
and the chest pain so let's dive a
little bit deeper into the actual drugs
and the dosing
so to treat the acute angina we said we
used nitroglycerin
the brand name is nitrostat meaning
immediate use right so nitrostat
and here we have the dosing of 0.3
to 0.6 milligrams sublingual
every 5 minutes again we're using this
to treat
and it's very quick acting so
a patient can actually use this up to
three times
and the way we want to counsel them is
first we want them to sit down
we want them to dissolve under their
tongue
and then they have to call 911
if their angina persists after the first
five minutes
so after the first dose if they don't
feel well
and they're still having chest pain they
need to call 9-1-1
so that the paramedics can come assuming
that the second or third dose doesn't
work
because it is an emergency now for the
chronic
preventative nitrates we have
isoscorbide
mono nitrate brand name is emder
der because of duration they last a long
time
the dosing is anywhere from 30 to 240
milligrams
by mouth daily now it is extended
release
it does work for 12 hours but it also
requires
a 12 hour nitrate free interval
if you don't take a 12 hour break every
day
then these medications stop working you
build up essentially a taller
and the second medication is the
isosorbide
dinitrate or eyesore dill
and the dosing is 40 to 160 milligrams
by mouth daily
this is also extended release and this
one also requires
that 12 hour nitrate free interval
now one thing from the chronic side
versus the acute side
these chronic medications have to be
swallowed whole
right they're not sublingual they don't
dissolve
they need to swallow it whole you can't
chew break or crush these
extended release capsules and tablets
all right so let's talk about some side
effects and drug interactions
so the big things here is patients
taking these nitrates can have
headache we could see them having
flushing
so redness they could become dizzy
or they could have something called
orthostatic hypotension
which basically means low blood pressure
when they get up too
quickly so they get very light-headed
now
all of these side effects have to do
with vasodilation
right so as we dilate those veins we get
these very distinct side effects
now we do need to talk about drug
interactions
and there is one that you need to know
you cannot
use nitrates with pde5 inhibitors
these are erectile dysfunction drugs so
think of
viagra the dalaphil which is cialis
and essentially when both of these drugs
are used at the same time
it could cause severe hypotension
so a dramatic drop in blood pressure
and a quick overview on how it causes
this severe hypotension
remember when we take nitrates it has
nitric
oxide which help with the formation of
cyclic gmp which then cause
vasodilation now the cyclic gmp
that causes the vasodilation is broken
down by
pde5 right so
if we take a pde5 inhibitor
we stop the breakdown of cyclic gmp
which increases the vasodilation effect
even more to the point where it could be
potentially harmful
for our patients all right so we made it
to the end so let's have a real quick
summary of everything we learned
so we know ischemia which means not
enough oxygen for a tissue like the
heart
is due because of an imbalance of oxygen
supply
and oxygen demand this imbalance can
cause something called
angina pectoris which is that chest pain
so then we talked about nitrates and how
they work
so we know it they released nitric oxide
which helped with the formation of
cyclic gmp
causing vasodilation which actually
improved
the oxygen supply to the heart and then
we talked about three major drugs we
talked about nitroglycerin
which is our nitrostat and then our two
chronic medications
isosorbide mono nitrate and isosorbide
dinitrate so these two here remember
they need a 12 hour nitrate free
interval to prevent that tolerance
buildup
and then we also had our acute angina so
the nitrostat
and then the chronic agents that we just
talked about
then we went into the side effects
remember everything that had to do with
vasodilation
so we had headache flushing dizziness
orthostatic hypotension and then we had
our
big drug interaction and remember we
can't use those nitrates with any
pde5 inhibitor because of the severe
hypotension
so that's everything so let's jump into
the short quiz to see what we retained
question 1 which of the following is
approved for acute angina
question 2 nitrates increase which
molecule to allow
vasodilation
question 3 nitrates are contraindicated
with
which of the following
question 4 how long should the
nitrate-free interval be
for isosorbide dinitrate
and thanks for watching guys i hope you
learned something and a special shout
out to my supporters
[Music]
[Music]
you
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