- [Voiceover] Oxymetazoline.
This is an important topic.
We give it a three out of five
on our importance or yield scale.
You really should know something about it
but it's not necessarily really high yield.
The most common brand name that you'll see this called
in the clinic is Afrin, so you should think about that,
especially in the winter months,
when people are coming in with congestion or rhinorrhea.
You really will see this medicine used
at least a little bit.
It is a synthetic direct-acting adrenergic agonist,
works on the α1 and α2 receptors.
It is usually given as a topical nasal decongestant.
So what does that mean?
Well, that basically means you spray it up your nose.
You have a spray bottle and you spray it at the same time
that you inhale, and that mist goes back and covers
the nasal mucosa, thus causing the effects.
Now on to the mechanism of action.
So this is, again, it's a direct-acting α1, α2 agonist.
That's a five out of five, you can see on the left there.
You've got to know that.
If you don't at least know that much about this drug,
you're gonna fail the question.
It works mostly on the α1 receptor over the α2.
Think about what α1 does.
It's a vasoconstrictor.
Makes perfect sense why it works
when we spray it up the nose.
If someone comes in congested, dripping and uncomfortable,
this medicine is gonna cause those vessels
in the nasal mucosa to clamp down,
thus decreasing the edema,
which is the congestion and a little bit
of the uncomfortable sensation,
and also decrease the rhinorrhea, which is the dripinness,
which could be causing a cough and other things.
They're gonna walk out of your clinic
in a couple of minutes even feeling much better.
It really only takes a few minutes for this to kick in.
Next, a little bit less yield, three out of five,
the α2 affects, okay?
That's not really what we use the medicine for.
That's why it's got a lower yield to it.
It works on the α2 subtype A adrenergic receptor mostly.
And you're even not really gonna see this
unless you're giving higher doses.
So what does α2 stimulation do?
Well, do you remember clonidine, the medicine clonidine?
What is clonidine?
Clonidine is an α2 agonist.
What do we use it for?
We use it to decrease blood pressure,
and that's what this is going to do at very high doses.
In fact, this is even sometimes called
the clonidine effect, and I wan't sure if I...
I thought about this a little bit,
whether I should put this in the side effects
or if I should put this in the mechanism of action.
And I decided to put it in the mechanism of action
because we're talking about the receptors
and kind of what it does.
But you can also think of it as a side effect,
not really wanting to decrease someone's blood pressure
but it happens, or it can happen at high doses.
On to the clinical uses, we already hit this on the head,
five out of five, you absolutely have to know.
Great drug for a nasal decongestant.
What about the second one there, epistaxis?
Well, that means a nosebleed, and I've seen this work.
Actually, a young boy comes into the clinic,
difficult to control nosebleed,
and we just can't get it to stop.
Finally, someone smart in the back says,
"Hey, why don't we try Afrin?"
And you know what, that solved our problem.
That gave him enough time to achieve homeostasis
and we got the problem fixed, went out the door happy.
Lastly, the side effects
Five out of five, you got to know it, rebound congestion,
also called rhinitis medicamentosa.
It's more of a technical term.
Basically, if patients use this medicine
for more than a few days,
officially we tell the patients three days
but in reality maybe more like five or seven.
If they use it longer than that amount of time,
the nose is going to depend on that medicine.
I think of it as becoming addicted
so that the nasal mucosa gets addicted.
It has to have this drug or else
it's just not gonna stop running.
The physiology is a little bit more difficult than that,
but basically you've got a problem.
You have to have this medicine or your nose is going to run.
So tell your patients, don't take it longer than three days
or you're gonna have a problem, okay?
The next two bullets there, headache and insomnia.
So far, we've really only discussed
the local effects of oxymetazoline,
but in truth, it is absorbed systemically.
And actually, a lot of things can be absorbed systemically
through the nose, think about it.
What about cocaine? People snort cocaine.
It wouldn't be a very fun drug
if it stayed locally in the nose, right?
So some of this is gonna be absorbed and it is very likely
that it could cause them a small headache
or maybe some insomnia and a little bit of burning
and itching in the nose.