This is Chapter 1 - Gastrointestinal and in this video, we'll be discussing antiemetics.
Antiemetic means anti-nausea or vomiting, and the main
neurotransmitters that are targeted with controlling nausea is
dopamine, serotonin
histamine, and muscarinic receptors, which are in the
parasympathetic nervous system.
We'll have four examples today in four different classes.
Our example of an antihistamine is meclizine or Dramamine.
Our anti-dopaminergic agent is prochlorperazine, otherwise known as Compazine.
Our serotonin receptor antagonist is ondansetron or Zofran,
and our anticholinergic example is scopolamine or Transderm-Scop.
Now, we'll go over some practice questions.
'A medication commonly used with aprepitant to prevent chemotherapy induced nausea and vomiting is?'
We will have the same four answers throughout the rest of the video,
so A) will be meclizine, B) will be scopolamine
C) will be ondansetron and D) will be prochlorperazine.
The correct answer is C) ondansetron.
Meclizine, scopolamine and prochlorperazine are incorrect
as they are not usually used to prevent chemotherapy induced nausea and vomiting.
Ondansetron is given
with the highly emetogenic or moderately emetogenic
chemotherapy agents to prevent nausea during and after the chemotherapy infusion
Depending on how much of a risk we have for
the chemotherapy agent causing nausea and vomiting or if it can cause the late-onset nausea and vomiting
can kind of dictate our therapy, so the three drugs we can also add on board to prevent either
the chemo-induced nausea and vomiting or the delayed
chemo-induced nausea and vomiting is a
5-HT3 Receptor antagonist like ondansetron,
the aprepitant, or also a steroid like dexamethasone.
Okay, now we'll just change all of the practice questions, but keep the answers the same so that the question
makes each answer correct. Question three - 'An antihistamine that is available over-the-counter is?'
The correct answer is A) meclizine.
B) scopolamine is available over-the-counter, but it is an anticholinergic agent.
C) and D), ondansetron and prochlorperazine,
both need prescriptions.
Meclizine is an antihistamine and it's often used for motion sickness and just generalized nausea.
Practice question four - 'A patch used to prevent motion sickness that is placed behind the ear is?'
The correct answer is B) scopolamine.
Meclizine, ondansetron, and prochlorperazine,
none of those have patch formulations.
Scopolamine does have the patch formulation and it's often used to prevent nausea, especially on cruise ships.
You place the patch behind your ear in advance of your trip,
and it's pretty long-acting as well, and it works good to prevent motion sickness before it happens.
Practice question five - 'An antiemetic that causes extrapyramidal symptoms or EPS as a side effect is?'
The correct answer is D) prochlorperazine.
A), B) and C) - meclizine, scopolamine and ondansetron,
are incorrect because they don't have any extrapyramidal side effects associated with them.
Meclizine is an antihistamine,
so you can get some drowsiness, and it also has anticholinergic properties
so we can see potentially a dry mouth or constipation.
Scopolamine is exclusively an anticholinergic
agent so we also think of the drying side effects like constipation and dry mouth.
Ondansetron works to block serotonin, so some side effects could be headache or diarrhea,
but prochlorperazine as you'll recall is a dopamine blocker.
The side-effects will be similar to the antipsychotics that block dopamine, so it can have those extrapyramidal symptoms.
There's four symptoms associated with EPS.
The first is dystonia which is just tensing of the muscles in the neck or back,
akathisia which is restlessness,
parkinsonism which is tremor, rigidity or slow movement,
and then tardive dyskinesia, which is uncontrollable spasms of the face and tongue.
Prochlorperazine is often used to treat nausea of unknown sources