Okay, so here's the best study tip I
have for you for studying PNS drugs.
If I'm looking at a drug, all I need to know
is what receptors are involved in that drug.
Is it alpha-1, is it beta-1, is it
dopamine? Which receptor is involved?
Then I need to know, is
the drug an agonist?
Remember, winner key - is that gonna
activate that receptor or is it an antagonist
meaning it's going to bind to the receptor
but block the action of that receptor.
So you see why that
chart is so important.
If you know what the receptor is, where it's located
and what happens when that receptor is activated,
then you've got the
key to PNS drugs.
So if I look at a drug, I know which receptors are
involved with that drug, it might be one or more.
I know if the drug is an agonist or an antagonist,
that will tell me what to expect of the drug.
Now, in case you're not processing
this, that is really good news.
Because you don't have to memorize so much, you just
need to understand which receptors are involved,
if it's an agonist or an antagonist
and then you know what the drug does.
Let's walk through
Okay, look at this simple chart.
Epinephrine, it involves alpha-1,
alpha-2, beta-1 and beta-2.
Now what I want you to do is look
at your downloadable material.
Look at where you have where alpha-1's located,
what happens when the receptor is stimulated.
Look at alpha-2s, where are they located,
What happens when alpha-2 is stimulated?
Same thing with
beta-1s and beta-2s.
Go ahead, I'll wait
just a minute.
Okay, when you look at all that epinephrine
can do, you'll understand why we use it.
Now I'll go into that in a little
more detail in just a minute
but I want you to see, you can do
the same thing with dopamine.
You see the receptors that are involved when we
give the drug dopamine, so you know what to expect.
Dobutamine is only beta-1s, right? so it's
only gonna go after the things on your heart.
And where's the other location of
your beta-1s? right, the kidneys.
Norepinephrine, well that's a name of a
neurotransmitter but it's also the name of the drug.
and it's going to hit
alpha-1, alpha-2 and beta-1.
So this is it, if you can look at a
simple chart like this and re-create it,
you'll have the key to
understanding adrenergic agonist.
So let's talk about it.
Epinephrine, we look at those four receptors, you already
compared them to your chart, now that would make sense.
Why would it help
us in acute asthma?
sweet! because it goes after the beta-2s
that will help us bronchodilate.
What about anaphylactic shock? well, it's
that whole response system that we've got.
Alpha-1, alpha-2, beta-1 and beta-2 are gonna be
really helpful in the series of anaphylactic shock.
We also can use it in local anesthetics because
it'll help increase the duration of action.
Well that sounds really fancy
but what does that mean?
Well if I put epinephrine, just put it on subq on
your skin, it's gonna cause, vasoconstriction.
If I cause vasoconstriction then when I put in a local
anesthetic, it's gonna stay in that area longer.
So look at all that I can
use epinephrine for.
I can use it for an asthma attack, I
can use it for anaphylactic shock
or I could use it to make sure a local anesthetic stays
right where I need it to for a longer period of time.
All by understanding which
receptors are involved.
Now norepinephrine, we've got alpha-1,
alpha-2, we could use that in shock.
Now think about how that
helps also some beta-1.
Isoproterenol, beta-1, beta-2,
we can use that for asthma.
I want you to work your way
through the rest of your chart
and see if you can figure out how
these would each be helpful.
Okay, now as you work
through those on your own,
I hope you'll see the benefit of understanding
what the receptors do and how they work.
That's why we use norepinephrine in shock for example,
because of it's impact on the alpha-1 and alpha-2s.
Isoproterenol helps asthmatic patients 'cause beyond those
beta-2 receptors, we can also use it as a cardiac stimulant
because of it's effect on the beta-1
receptors, and so on and so on.
See, the key is not just memorizing every
drug and every side-effect and every impact.
Know the receptors, know where they're
located, know what their job is
and if that drug is an agonist or an antagonist and that's
gonna make your studying much more straightforward.
Then you'll still have to invest a
lot of effort but I promise you,
you're much less likely to get confused
as you're wrapping all that up.