Chapter 5 Neuro, this is the second of three videos about antidepressants, and in this video, we'll be focused on SSRIs.
As you recall from the previous video, SSRI stands for selective serotonin reuptake inhibitor.
This works by
preventing the breakdown of serotonin within neurons. Today,
we'll be looking at four different drugs in the SSRI class. We'll start with citalopram, otherwise known as Celexa.
Escitalopram, otherwise known as Lexapro, sertraline, which is Zoloft, and fluoxetine, which is Prozac.
Practice question number one: 'An
SSRI that can cause dose dependent QT prolongation is?' here
we have our our four options that we'll be working with in this video.
The correct answer is A). The FDA came out with a warning about
QT prolongation, so now there are dose maximums in different patient populations.
So the dose maximum in elderly patients is twenty milligrams per day, and in adults it is 40 milligrams per day.
With this QT prolongation warning, we want to make sure that we get an electrocardiogram of every patient before we start them on this medication.
B) C) and D) are incorrect because there is no FDA warning about the QT prolongation with any of these other medications.
For the next few questions, we're going to change the question to make each of the other answers correct.
So question 3: 'An SSRI that is an s-isomer of a different SSRI is?'
The correct answer is B).
Escitalopram is the s-isomer of citalopram, and as you can recall from the gastrointestinal
lectures, it's kind of like omeprazole and esomeprazole, s is the sinister, more active
biological form. That is the same thing that escitalopram is to citalopram.
It only takes ten milligrams of escitalopram and that's about the equivalent of 20 milligrams of citalopram.
Citalopram is incorrect because it contains both the more active s-
isomer and the r-isomer, and sertraline and fluoxetine don't have any isomers or
any other available products with different isomers of those two medications.
Question four, make B) correct: 'An SSRI
that is one of the safer SSRIs for pregnancy and has harsher GI side-effects is?' and the answer is C) sertraline.
Sertraline, the GI side effect we especially see even though they're common in all of the medications,
this one has quite a bit higher chance of diarrhea.
This one also, while a lot of them can be used in pregnancy, this one has historically been pretty common.
A) and B) are incorrect - they have less severe GI effects than the sertraline, and then D) is incorrect because
fluoxetine has less severe GI effects
and it also in different studies has potentially some effects on the baby if used in pregnancy.
Question five: 'An SSRI that can also be used for premenstrual dysmorphic disorder or
PMDD
and has a long half-life is?' D) fluoxetine. A) and B) are incorrect because there is no
premenstrual dysmorphic disorder
indication for citalopram or escitalopram.
Sertraline is actually indicated for PMDD, but it has a shorter half-life.
Fluoxetine is correct because it is indicated for depression and PMDD and it has a really long half-life.
The way that works is fluoxetine and its metabolites
are able to stay in the system longer, which can be good for those who can't remember to take their medication.
Since it does linger in the system a little bit longer, if we do switch to a new SSRI,
we need to be concerned because the patient will be at higher risk of serotonin syndrome.
We can remember that fluoxetine is a long-acting medication because
it starts with 'flu-', so fluoxetine is like the flu and it typically lasts around a week.