March 22, 2023

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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 reactions

So the main adrs uh 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 first-line 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 a

Partial or a tonic chronic seizure and they don’t specify a specific sub-type 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 valproate is usually your go-to adverse drug reactions let’s talk about a few the ones you should know are anemia hepatotoxicity pancreatitis

And spina bifida 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 valproate 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

Spina bifida so the o it was literally just the whole or the pouch through which you have the spina bifida occurring so all pro from valproate all pro anemia liver which is hepatotoxicity pancreatitis and then r big o is the little spina bifida 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 all pro athlete who is a very salty person is dez bryant the wide receiver for the dallas cowboys so that’s valproate all pro from valproid now let’s talk about phenytoin phenytoin’s mechanism is that you have an inhibition or decrease activity at voltage-gated sodium channels so same exact mechanism minus the gaba part

There’s really no main indication for phenytoin so the adverse drug reactions that you should know about are gingival hyperplasia and fetal hydantoen syndrome in addition to that i want you to know that this drug undergoes zero order 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 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 toe and well to remember phenytoin we’re going to think about a tow truck because feni towen you’re going to need toe in by a tow truck so if they don’t salt the roads your car will need a toe in right

Your car will need to be towed the toe in from phenytoin and if they don’t salt the road 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 towing and this mnemonic goes beyond just the mechanism because let’s think about these things gingival hyperplasia well i think

About snow hyperplasia right snow everywhere just like there’s gingival hyperplasia where the cells are growing out of control i think of salt or excuse me snow hyperplasia fetal height and tone syndrome is an easy one to remember because the word ends in toein and phenytoin also ends in tone so you don’t even really need a mnemonic to remember that but fetal

Height and tone syndrome just so you know and i do suggest that you google it is craniofacial abnormalities and limb problems in addition in addition to mental retardation so that if you take phenytoin when you’re pregnant your baby could have fetal height and tone syndrome toein um and phenytoin but again the way that i remember the this by if they don’t salt

The roads your car will need a toe in salt for the voltage-gated salt channels um if if there’s a lot of snow out there there’s gonna 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 gingival hyperplasia i think about snow

Hyperplasia just snow everywhere which is why you’re going to need a toe in when they don’t salt the roads and then fetal height and toe and syndrome again easy to remember just because it ends in toeing so that’s everything you should know about phenytoin so close your eyes think about phenytoin and when you can’t remember anything about this drug just remember

Toein like the tow truck why are you being towed well they didn’t salt 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 gonna have to induce the tow trucks to come dig our cars out of the snow so that is phenytoin now we’re going to talk about

Ethosimide the mechanism of ethosexumize 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 t-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 absence seizures so

Obscene seizures are always treated by ethosoxamide the main adverse drug reaction to know is stevens johnson syndrome so the mnemonic here is really really easy absance seizures suck or sucks um absence for absence seizures and sucks for succsimide so absent seizures suck or seizure sucks the other thing that i really want you guys to to memorize is i have this

Clever mnemonic to remember all of the anti-epileptics that cause steven 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 necrolysis 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 ethosoxamide so the mnemonic 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 stephen 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 stephen and johnson and each of these names signifies a drug so ethosuccsimide is ethan so if you give ethosuxamide you can cause stevens-johnson syndrome and ethosuccimide 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 stephen and johnson’s syndrome so ethan is ethosucciamide 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 carbamazepine so carbamazepine’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 trigeminal neuralgia

Really really high yield the for some reason 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 carbamazepine causes

Stevens-johnson syndrome and if you remember our boy band our friends ethan carl larry stephen and johnson carbamazepine is represented by carl so carl for carbamazepine let’s talk about trigeminal neuralgia really quickly so trigeminal neuralgia is a problem in the distribution of the trigeminal nerve which supplies sensory innervation 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 usmle or comlex it’s going to be sharp shooting

Stabbing lancinating pain and the distribution of the muscles that you see here and again they’re in they’re innervated by the trigeminal nerve which is why this is called trigeminal neuralgia so when this happens you treat with carbamazipine 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 carbamazepine and you eat or chew carbs with your cheeks 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 is treated with carbamazepine so

You chew carbs with your cheek and then don’t forget carl is carbamazepine in our group of friends ethan carl larry stephen and johnson so carl or carbamazepine will cause stevens-johnson syndrome now let’s talk about lamotrigine so lamotrigine’s mechanism is that it inhibits voltage-gated sodium channels and it also has activity at glutamate receptors now uh

Lamoture green also is one of the drugs that causes stevens-johnson syndrome so larry is lamotrigine so we’re done with our group of friends now we talked about ethan which is ethosuccsimide we talked about carl who’s carbamazepine and now we’re finishing with larry who’s lamotrigine 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 a glutamate receptors this is really high yield 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 lamotrigine 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 lamo lamo for lamotrigine so from the perspective of the seizure the seizure’s like oh

It’s so lame you’re turning me off at voltage-gated sodium and glutamate receptors lame-o for lamotrigine and then don’t forget lamotrigine 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

Benzodiazepines and barbiturates 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 benzos increase the frequency of chloride channel opening and barbiturates 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 usmle or comlex so let’s talk about this how do

You remember which one’s frequency and which one’s duration well instead of saying barbiturate i want you to say barbiturate barbiturate so dur for duration so barbiturates increase the duration of chloride channel opening and benzos increase the frequency of chloride channel opening so if you remember the barbiturate just by process of elimination you’ll know

That benzos have to be frequency so that’s barbiturate for dur for duration um the only other thing is that you should know that benzos 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 give them a benzo that’s really all you need to know about benzos and barbiturates as far as uh seizures

Are concerned we’re going to talk now about levityracetam 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 blah blah what’s the drug so you got to know that levity

Acetaminophen 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 levity your acetaminophen 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 levitor acetamine 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 tiaga bean and the gabatran 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 taya gabin and vig gabba trin so gab 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 they ask you the mechanism look at the name take the gas and take the easy point we’re going to finish up with topiramate so topiramates 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 ins with topiramate i want you to think of a tow pirate mate or a pirate ship here’s our pirate ship and just so you know a pirate ship sails on salt water 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 mnemonics 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 carl larry ethan stephen and johnson the five friends who call stevens-johnson syndrome you can remember ethan larry and carl as etho succimide lamotrigine

And carbamazepine remember that carbamazepine treats trigeminal neuralgia remember that ethosuccsimide treats absence 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 mnemonics because they’re free points good luck

Transcribed from video
Pharmacology – ANTIEPILEPTIC/SEIZURE DRUGS By Dirty Medicine