Master Anti-Epileptic Drugs: Mechanisms, Indications & Side Effects Simplified

So when we go through this, we're going to cover three main things. Now, some drugs are not going to have an

indication. Some drugs are not going to have a high yield adverse drug reaction. And if that's the case, I'll point it

out. But when we go through these drugs, we want to think about the mechanism, the indication, and the main side

effects or adverse drug reaction. So the main ADRs. Um, don't worry guys. I want you to sit back, take a deep breath, and

just follow my lead. We're going to simplify all of this in a really high yield fashion. So let's start with

valproate, also known as valproic acid. So the mechanism of valproate is that we're going to inhibit or decrease the

activity at voltage gated sodium channels. In addition to that, we're going to increase the activity of GABA.

So think of sodium in this lecture as like sort of excitatory. So when you decrease voltage gated sodium channels,

we decrease the excitation that causes seizures. Likewise, GABA is an inhibitory neuron. So if we increase

activity of GABA, we're increasing inhibitory activity, which means we're getting inhibited, which tones down the

excitation in the brain that causes seizures. So valproate decreases or inhibits the voltage gated sodium

channels and increases GABA. Valproate is really a firstline medication here. And if you're taking your exam and they

want you to pick what uh anti-epileptic drug you're going to give to somebody who has a you know like a just a general

seizure um a partial or a toniconic seizure and they don't um specify a specific subtype of seizure and you'll

understand what I mean as we go through this lecture but generically speaking if you have to pick a first-line medication

valate is usually your go-to. Adverse drug reactions. Let's talk about a few. The ones you should know are

anemia, hpatotoxicity, pancreatitis, and spinobipida. Right? So, how do you remember this? Well, when

you think of valproate, I want you to think of all pro. So, you take the alpro out of valrate. So, all pro. That

reminds us of two things. The if we drop one of the L's, all pro stands for anemia, liver, pancreatitis. And then

the little R big O reminds me of the hole that you get in the neural tube defect of spinobipida. So the O is

literally just the hole or the pouch through which you have the spinobipida occurring. So all pro from volate all

pro anemia liver which is hpatto toxicity pancreatitis and then our big O is the little spinobipida. The other

reason that I think all pro is because we need to have a way to memorize the mechanism of valproate. And if you're

not a sports fan, I apologize, but an allp pro athlete who is a very salty person is Dez Bryant, the wide receiver

for the Dallas Cowboys. So that's Val Pro8. All pro from Valproate. Now let's talk about fenito. Phenito's

mechanism is that you have uh an inhibition or decrease activity at voltage gated sodium channels. So same

exact mechanism minus the GABA part. Um there's really no main indication for fenytoin. So the adverse drug reactions

that you should know about are gingivvil hyperplasia and fetal hyantoin syndrome. In addition to that I want you to know

that this drug underos zeroorder kinetics which means just to refresh your memory that the drug is eliminated

at a constant rate that does not change based on the amount of the drug. It's the same amount um per hour shall we say

that gets eliminated and it's a P450 inducer that's also really high yield. So how do we remember fanny towin? Well,

to remember fenny towin, we're going to think about a tow truck because fenny towin, you're going to need towin by a

tow truck. So, if they don't salt the roads, your car will need a towin, right? Your car will need to be towed.

The towin from fenny towin and if they don't salt the roads, salt reminding us that this inhibits voltage gated salt

channels. So, voltage gated salt channels. If they don't salt the roads, your car will need a towin. And this

pneumonic goes beyond just the mechanism because let's think about these things. Gingal hyperplasia. Well, I think about

snow hyperplasia, right? Snow everywhere. Just like the there's gingerville hyperplasia where the cells

are growing out of control. I think of salt or excuse me, snow hyperplasia. Fetal hide and towin syndrome is an easy

one to remember because the word ends in towen and fenitoin also ends in towin. So you don't even really need a

pneumonic to remember that. But fetal hide and towin syndrome just so you know and I and I do suggest that you Google

it is cranioacial abnormalities and limb problems in addition in addition to mental retardation. So that if you take

feny towin when you're pregnant your baby could have fetal hide and towin syndrome towin um and fenytowin but

again the way that I remember the this by if they don't salt the roads your car will need a towin salt for the voltage

gated salt channels um if if there's a lot of snow out there's going to be zero order right there's going to be

absolutely no order on the roads um it's a P450 inducer so if they don't salt the roads you're going to be inducing tow

trucks to come rescue the cars Gingerville hyperplasia. I think about snow hyperplasia. Just snow everywhere,

which is why you're going to need a towin when they don't salt the roads. And then fetal height and towin

syndrome. Again, easy to remember just because it ends in towin. So that's everything you should know about fenny

towin. So close your eyes, think about fenny towin. And when you can't remember anything about this drug, just remember

towin like the tow truck. Why are you being towed? Well, they didn't insult the roads, which means there's snow

everywhere. There's snow hyperplasia, zero order kinetics because there's zero order on the roads. And it's a P450

inducer because we're going to have to induce the tow trucks to come dig our cars out of the snow. So that is fenny

towin. Now we're going to talk about ethosuxomide. The mechanism of ethosomide is that it inhibits the

T-type calcium channels. So just remember the word calcium. If you see calcium, that's the answer. They're not

going to make you pick Type from any other type. You're going to see calcium and that's going to be the answer. The

indication here, and this is a really high yield one, is absance seizures. So absant seizures are always treated by

ethosomide. The main adverse drug reaction to know is Stevens Johnson syndrome. So the pneumonic here is

really really easy. Absance seizures suck or sucks. Um absance for absance seizures and sucks for suomide. So

absance seizures suck or absance seizures sucks. The other thing that I really want you guys to to memorize is I

have this clever pneumonic to remember all of the antiepileptics that cause Stephven Johnson syndrome. So Stevens

Johnson syndrome is a really really nasty rash that you can get. And if you get it, it can develop into something

which is worse called toxic epidermal necro necrolyis. And Google what that looks like. It's hideous. But what you

need to know is the drugs that cause the rash. Because if you put a patient on a drug and all of a sudden they get some

nasty looking rash, then you need to stop the drug. So Stevens Johnson syndrome, one of the drugs that causes

it is ethosomide. So the pneumonic that I have to remember the different drugs that cause it are I think about five

male friends and their names are Ethan, Carl, Larry, Steven, and Johnson. This is actually a picture of the band in

sync, but that's the picture I always I've always used in my own notes. So Ethan, Carl, Larry, Steven, and Johnson.

And each of these names signifies a drug. So ethosuxomide is Ethan. So if you give ethosomide you can call Stevens

Johnson syndrome and ethosomide is represented in the group of friends by Ethan. Of course Steven and Johnson are

not drugs but they just tell you that Ethan, Carl and Larry can cause Steven and Johnson syndrome. So Ethan is

ethosomide and as we go through this lecture you'll you'll meet Carl and you'll meet Larry. These are all drugs

that cause Stevens Johnson syndrome. So now we're going to talk about carbomazipene. So carbomazipene's

mechanism is that it increases the refractory period of voltage gated sodium channels and when you increase

the refractory period of anything it means you're increasing the time that that receptor is not working and by

doing that you're still blocking excitation and when you block excitation you treat seizures. High yield

indication here guys is trigemina nur trigeminal neuralgia. Really really high yield. The for some reason they the

boards love to go after trigeminal neuralgia. They're going to describe a patient to you who has trigeminal

neuralgia and they will ask you what drug do you give or what's the mechanism of that drug or what's the side effect

of that drug. All of this is tied together. So so pay close attention here. Carbomasopene causes Stevens

Johnson syndrome. And if you remember our boy band, our friends Ethan, Carl, Larry, Steven, and Johnson,

carbomaszipene is represented by Carl. So Carl for carbomaszipene. Let's talk about trigeminal neuralgia

really quickly. So trigeminal neuralgia is a problem in the distribution of the trigeminal nerve which supplies sensory

intervation to various muscles of the face in the V1, V2, and V3 distribution. You can see a picture of it right there.

But basically someone has sharp shooting lancinating pain over their cheek up back to just over the top of the ear.

That is trigeminal neuralgia. And the pain is debilitating. You will not miss this on an exam. If they give this to

you on USML or COMLX, it's going to be sharp shooting stabbing lancinating pain in the distribution of the muscles that

you see here. And again, they're they're innervated by the trigeminal nerve, which is why this is called trigeminal

neuralgia. So when this happens, you treat with carbomazipene. And I told you that that's super high yield. So how do

we remember this? My pneumonic is that you chew carbs with your cheek. So the the carbs for carbomazipene and you eat

or chew carbs with your cheek. So imagine literally eating a sandwich. You're going to be using the facial

muscles that are innervated from in the sensory distribution by the trigeminal nerve. So you eat carbs or you chew

carbs with your cheek. That reminds me that trigeminal neuralgia uh is treated with carbomazipene. So you chew carbs

with your cheek. And then don't forget Carl is carbomazipene in our group of friends Ethan, Carl, Larry, Steven and

Johnson. So Carl or carbomazipene will cause Stevens Johnson syndrome. Now let's talk about lamotrogene. So

lamotraine's mechanism is that it inhibits voltage gated sodium channels and it also has activity at glutamate

receptors. Now uh lamotine also is one of the drugs that causes Stevens Johnson syndrome. So Larry is lamotine. So we're

done with our group of friends now. We talked about Ethan which is ethosomide. We talked about Carl who's carbomazipene

and now we're finishing with Larry who's lamotrogene. So those three friends or those three drugs will cause Stevens

Johnson syndrome. So that's really really high yield. How do we remember that this has activity not only at

voltage gated sodium channels but also at glutamate receptors. This is really high yield um as far as mechanisms go

because it's the only drug that has activity at both voltage gated sodium and glutamate receptors. So from the

perspective of the seizure and this is our cartoon seizure. From the perspective of the seizure, if you give

somebody lamotine, it has two mechanisms at two different receptors. So the seizure who really wants you to keep

seizing, the seizure looks at this double mechanism going on and says, "Wow, you're attacking me at two

receptors." That's lameo. Layo for lamotraine. So from the perspective of the seizure, the seizure is like, "Oh,

it's so lame. You're turning me off at voltage gated sodium and glutamate receptors. Layo for lamotraine." Um, and

then don't forget Lamotroine is Larry Stevens Johnson syndrome. So, we're flying guys. I hope you're able to keep

up here, but it's not that bad if you get these pneumonics down. Let's quickly talk about some of the easier ones to

remember. Now, so these are uh bzzoazipines and barbbiterates. And really, the only thing that you need to

know about these guys is their mechanism. So, they increase the activity at the GABA A receptor. And the

way that they do this is that benzo increase the frequency of chloride channel opening and barbituates increase

the duration of chloride channel opening. And this I want to pause for a second because this is really really

high yield. It's not difficult to remember but it's high yield because exams love to go after the differences

in these mechanisms because the only difference is the word frequency or the word duration. And you will see a

question on this in some question bank maybe even on your USML or complex. So let's talk about this. How do you

remember which one's frequency and which one's duration? Well, instead of saying barbbiterate, I want you to say

barbidurate. Barberate. So, dur for duration. So, barbbiterates increase the duration of chloride channel opening and

benzo increase the frequency of chloride channel opening. So, if you remember the barberate just by process of

elimination, you'll know that benzo have to be frequency. So, that's barbbiterate for dur for duration. Um, the only other

thing is that you should know that benzo are used as abortive means of stopping a seizure. So, if someone's seizing on the

table and you need to stop the seizure, you you give them a benzo. Um, that's really all you need to know about benzos

and barbiterates as far as uh seizures are concerned. We're going to talk now about levitam.

So, the mechanism is unknown and you may think that that's something that you won't be asked, but I have seen the

question come up and the answer is unknown mechanism. Or maybe in the clinical vignette they'll say a drug

with an unknown mechanism blahy blahy blah what's the drug? So you got to know that levitator acetam is an unknown

mechanism. I know that sounds funny sounds stupid but just know it. So how do we remember this? I want you to think

when you think of leviter acetam I want you to think of a magician making somebody levitate. How does he do the

levitate trick? I don't know. That's I don't know. Reminds me that the mechanism is unknown. So how do you

levitate? I don't know. Unknown mechanism. I just don't know. Levitate for levator acetam. I mean, how simple

can we get, guys? I'm really boiling this down. Let's talk about two of the lower yield drugs that I've included for

completeness sake. Tiagabine and vagabitan. And I'm probably butchering the pronunciation here, but who cares?

Mechanism GABA. It has activity at GABA. Um, the way that you remember this is you look at the name T gabin and vaba.

So, GABA or GABA is in the name. It's got activity at GABA. That's literally all you need to know. So, if you see

this drug and they ask you the mechanism, look at the name. take the gas and take the easy point. We're going

to finish up um with topyramate. So topyramate mechanism is that it it inhibits voltage gated sodium channels

just like a lot of the other drugs we've talked about today. Um how do we remember this? Well in with topyramate I

want you to think of a top pirate mate or a pirate ship. Here's our pirate ship. And just so you know a pirate ship

sails on saltwater salt for voltage gated salt channels. So that's it guys. That is all the anti-epileptic drugs.

That is all of their mechanisms all with pneumonics. All of the high yield indications and adverse drug reactions.

Some things in closing and in summary that I would like you to remember is uh Carl, Larry, Ethan, Steven, and Johnson.

The five friends who cause Stevens Johnson syndrome. You can remember Ethan, Larry, and Carl as ethosomide,

lamotrogene, and carbomasene. Remember that carbomasopene treats trigeminal neuralgia. Remember that ethosomide

treats absance seizures and remember some of the other stuff as far as mechanisms are concerned. And when

you're learning the mechanisms, it's something that you just unfortunately have to memorize. So go back and use

these pneumonics because they're free points. Good luck.