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ANTI SEIZURE DRUGS by professor fink

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In this Video Lecture, Professor Fink first defines epilepsy, seizure & convulsion and then identifies types of epilepsy. Professor Fink then presents the mechanism of action, clinical uses (including “Off Label Uses), and adverse effects of the most common drugs used in the management of epilepsy. Reference is made to phenytoin (Dilantin), carbamazepine (Tegretol), valproic acid (Depakote), ethosuximide (Zarontin), gabapentin (Neurontin), pregabalin (Lyrica), lamotrigine (Lamictal), and topiramate (Topamax).

Anticonvulsant drugs and collected drugs obviously used for epilepsy what is epilepsy what’s the difference between a seizure and a convulsion let me start with that epilepsy is associated with seizures about 1% of the population has these seizure disorders and that’s called epilepsy the word seizure a seizure is associated with increased and applets put this witness

Of this way an abnormal increase in electrical activity in the brain usually the cerebral cortex liked an increase an abnormal increase in electrical activity in the brain that is called a seizure and it gets this name seizure because this increase of electrical activity seizes the mind so that what cannot think normally at that moment so the normal consciousness has

Been taken away or seized in some respect now if a seizure is increased electrical activity in the brain what is the word convulsion me because we’re going to see that comes up in a moment the word convulsion convulsion is associated with activate abnormal activation of skeletal muscles so this is a convulsion is when this when seizures the increase in electrical

Activity in the brain leads to uncontrollable muscular contractions uncontrollable skeletal muscular contractions so the word seizure a seizure has nothing to do with necessarily a seizure does not mean that there are these uncontrollable muscular contractions that’s called a convulsion but a convulsion is caused or associated with the seizure not everybody who

Has seizures has convulsions all right not everybody who’s having this abnormal electrical activity of the brain starts to have uncontrollable muscular contractions some do some don’t and that in part is why there are different types of epilepsy or epileptic seizures so with that in mind we divide epilepsy into two broad categories generalized seizures and lower

Down partial seizures or focal seizures a generalized seizure is where we have this increase in electrical activity throughout the entire brain and thus a loss of consciousness consciousness means awareness and the most famous of generalized seizures that most of us have either witnessed we’ve seen or we’ve seen movies of it are tonic-clonic seizures or grand

Mal seizure the proper name is tonic clonic the old name was grand mall the word grand ball was french for a big bad a big bad seizure this is usually where it lasts we’ll a few a couple of minutes there is this increased electrical activity of the brain resulting in convulsions so there are these clonic jerking motions of the body so that there are convulsions in

Grand mal seizures and there are certain medications that are used to control tonic clonic seizures involving the whole brain that causes these uncontrollable muscular contractions or chronic jerky some people have these epileptic seizures that don’t just last for a few minutes but may last for longer than 30 minutes that’s called status epilepticus that’s clearly

More severe and prolonged another type is a petit mal seizure or an absence seizure petit mal means little bad seizure these just last a matter of seconds and this appears as somebody where they just buried for just a few seconds lose consciousness there’s a rapid increase in electrical activity in their brain and just for a few moments they’re not aware and then

It comes back again now anytime i ever mentioned that everybody says oh my gosh i have the tefal seizures because i like sometimes just like then all of a sudden i know where i know you weren’t doing what’s called daydreaming daydreaming so daydreaming is when you kind of let your mind want wander briefly and so you’re not aware of part of your act for that moment

You actually are aware you just don’t care wow all right you hear the teacher droning on in the background and you just don’t care and you kind of spaced out you’re spacing out that’s not a petit mal seizures okay a real petit mal seizure the person literally has no awareness of for a few seconds in this case there are no convulsions there’s no convulsions with the

Petit mal seizure it didn’t last too short of a time to cause any uncontrollable skeletal muscular contractions now there are also partial seizures and by partial were focal that means that this increase in electrical activity in the brain is localized it only involves certain small areas of the brain not the entire brain because it doesn’t involve does not involve

The whole brain but just small areas the person does not lose consciousness and in the other in the generalized seizures the person lost consciousness lost awareness but in the partial or vocal there is no loss in consciousness and they further subdivide these and in different categories it may involve us uncontrollable muscular activity because even though it’s

Just a small brain area that’s firing off it with increased electrical activity it may have involved a motor area which sends signals down the motor neurons activating muscles to what contract so we can get this what’s known as a simple focal seizure with which might include lip smacking or fumbling hands or picking it close or loss of awareness but usually about

That loss of awareness so again we’re not going into all the details and the different types of epilepsy there are we’re just mentioning that there are different types on page k to the anticonvulsant drugs we had once mentioned when we were first learning about how to evaluate the relative safety of a drug and we use the term therapeutic index ti therapeutic index

Which we said was the ratio between the ld50 of the ii d50 that some of the drugs that have the smallest therapeutic in this sex and therefore a very small narrow margin of safety between the therapeutic dose and the leath of those are antiepileptic drugs so these anticonvulsant sore antiepileptic drugs generally have a very narrow therapeutic index not surprising

They are affecting the brain and they’re affecting the brain in a powerful way they in general most of these drugs most of these drugs are cns depressants and let’s think about that for a moment does that make sense if the problem with epilepsy is abnormal increase that electrical activity in your brain does it make sense that the way the drugs we use to control it

Would decrease or slow down electrical activity in the brain so we use cns depressants to slow down electrical activity and prevent these epileptic seizures now again if you kind of think about it press a drug you’re depressed your slow down let’s speed it up let’s increase electrical activity if you’re have epilepsy let’s road no electrical activity because of

That most of them also cause drowsiness and fatigue because they are slowing down electrical activity of the brain many of these drugs not all but many of them have anticholinergic or another way of saying anticholinergic is atropine like actions they are like atropine atropine like actions paras and hath olynyk actions and therefore they cause their estonia again

The large proportion of drugs affecting the brain have this side effect of causing right now okay there are a whole bunch of these i’m not testing you on names of drugs just want to give you a general sense of what they’re doing the first drug that i mentioned i mentioning you’ve all heard of phenytoin phenytoin goes under a number of brand names including dilantin

There’s generics available it works by blocking sodium ion channels in neurons and therefore slows blom the generation of conduction of action potentials in that respect it’s somewhat like a local anesthetic isn’t it and so it’s used to control different types of epileptic seizures including grand mall but it’s also used for other purposes it is also used to treat

Or control trigeminal neuralgia also known as tic delarue does any member heard that term particular ooh all right so that some people have chronic pain associated with abnormal activity of their trigeminal nerve and they’re getting all this flow of sensory impulses from the face into their brain causing facial and so i called trigeminal neuralgia a particular

Root also dilantin is used for cardiac arrhythmias i’ve been before any drug that slows down electrical activity in the heart would do that in the brain or vice versa that’s most an electrical activity in the brain it would slow it down in the heart we had mentioned lidocaine if we say that word to you you think of local anaesthetic if you say the word lidocaine

To most physicians or nurses they think cardiac anti-arrhythmic it slows down electrical activity by blocking sodium ion channels so the bupa liner came and dilantin are used for these purposes and of course notoriously famous it does cause gingival hyperplasia which all of you tube tegretol is another drug used to control epileptic seizures it also blocks sodium

Ion channels and thus reduces or slows down electrical activity in the brain used to treat all types of epilepsy also used to the control of trigeminal pain and chronic pain syndromes in general on page k 3 you notice that at the top i would mentioned it can be used to treat manic depression so a lot of these have a lot of weird weird uses another one depakote

I don’t know if anybody’s running to depakote this works totally differently magnet i dilantin it works by enhancing gaba weapons now gaba and i’m not testing you on this but gaba gamma-aminobutyric acid is an inhibitory neurotransmitter in the brain think about this you can reduce electrical activity in the brain by either slowing down electrical activity by

Blocking sodium channels which but dilantin does or increasing inhibitory neurotransmitters of the brain and that’s what this drug does is it raises the gaba inhibitory neurotransmitter levels of the brain so this is also used to control certain types of epilepsy as well as control migraine headaches this is the only drug i know of that can cause hypersalivation

Now i don’t think it’s worth i’m not going to test you on that i don’t think you need to memorize it but it’s the only drug that i know it’s certainly the only drug that i’m presenting to you that actually causes over salivation if if anything and most drugs cause dry mouth it’s air estonia but this one actually increased the salivation another one so rotten can

Also cause gingival hyperplasia and phenobarbital evita barbuto is actually one of the earliest and oldest drugs used to control epilepsy it is a barbiturate senator and barbiturate sedatives are drugs that are used to cause sedation drowsiness sleep and makes sense that the very first drugs they tried to slow down this in abnormal increase in electric activity

In the brain and causes seizures is sedatives drugs that slow down make the person sleepy lethargic neurontin works by a different mechanism again i’m not testing you on it it actually inhibits voltage-gated calcium ion channels and synaptic knobs you might have learned in a physiology course that in order for any neuron to release a neurotransmitter from the

Synaptic knobs calcium ions have to flow into the synaptic knob to cause the release of the neurotransmitter exocytosis and so it actually works by blocking these three of calcium ions into the synaptic knobs again i’m not testing you on it it’s used to treat certain types of epilepsy it’s also used to treat off-label uses psychosomatic pain tinnitus migraines

And agitation all right there’s a topamax and on the next page mcdowell tempura is a new drug that works in a new novel way i’m not even going to get into what it does

Transcribed from video
ANTI SEIZURE DRUGS by professor fink By professorfink