Chapter 27: Drugs for Seizure Disorders

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Usually when we talk about a medical diagnosis, there's this expectation of, like, precision.

Yeah, we like things to be very visible and neatly categorized.

Right.

It feels like engineering.

You know, you break your arm, the x -ray shows that jagged white line, and the doctor just points and says, there it is.

Exactly.

It's physically obvious.

But then you step into the world of neurodevelopment and seizure disorders, and suddenly that x -ray machine is, well, it's pretty much useless.

Right, because you're dealing with an invisible electrical storm inside the brain.

And because the storm is invisible, the pharmacological landscape we use to fight it is just incredibly complex.

It is dense material.

In the United States alone, about 3 .4 million people have epilepsy.

Wow.

That's a lot.

Yeah.

So regardless of what specialty you eventually choose, you will encounter these medications.

Which is exactly why we're here.

Welcome to this custom -tailored deep dive designed specifically for you, the learner.

We know you're a dedicated college nursing student, and our mission today is to help you conquer Chapter 27 from Lenz Pharmacology for nursing care.

Right.

We're focusing exclusively on drugs for seizure disorders, and we aren't just going to memorize drug names here.

No, absolutely not.

We're going to figure out how to keep a patient's brain from short -circuiting while, you know, still preserving their quality of life.

And a really great place to start is with the terminology.

In clinical practice, we have to distinguish between a seizure and a convulsion.

Okay.

I always thought those were just like two words for the exact same thing, are they not?

Not quite.

It's a common misconception.

All convulsions are seizures,

but not all seizures are convulsions.

Wait, really?

How does that work?

Well, a convulsion specifically refers to abnormal motor phenomena, so the violent, visible jerking movements.

Okay.

But a seizure is the broader general term for all types of epileptic events.

Oh, I see.

So a seizure is the actual electrical storm in the brain, but a convulsion is only when that storm causes like visible lightning strikes in the muscles.

That's a perfect way to visualize it.

For example, a patient might have an absence seizure, which just looks like a brief period of unconsciousness.

Like just staring off into space.

Exactly.

A 10 -second blank stare.

The storm is raging in their brain, but there's no visible lightning, no violent movement at all.

That makes a lot of sense.

So where does this storm actually start?

It initiates in what we call a focus.

This is a highly localized group of hyper -excitable neurons.

And what makes them hyper -excitable?

It could be various things, maybe head trauma, a tumor, a genetic disorder, or even hypoxia at birth.

Right, okay.

These neurons just start discharging synchronously at very high frequencies, and the actual clinical seizure happens when the discharge from that focus spreads to other normal areas of the brain.

Kind of recruiting them to act crazy, too.

Yes, exactly.

Recruiting them to discharge abnormally.

And I imagine how far that storm spreads dictates the symptoms the nurse is going to actually see in the patient.

Precisely.

Based on the 2017 ILE system, we essentially have two broad categories, focal onset seizures and generalized onset seizures.

Focal meaning the storm stays localized to like one specific hemisphere or area of the brain.

Right.

And within that, you might see a focal -aware seizure.

Meaning they don't lose consciousness.

Exactly.

They might just have a twitching thumb or experience a sudden localized numbness.

Oh, wow.

They might even have an olfactory hallucination like smelling something that isn't really there.

Okay, but what if they do lose consciousness?

That's a focal -impaired awareness seizure.

They lose responsiveness, they might become motionless, stare with a fixed gaze, and perform repetitive purposeless movements.

Like what kind of movements?

Things like lip smacking or just kind of picking aimlessly at their clothes.

And I'm guessing a focal seizure can escalate, like the storm breaks containment.

It definitely can.

Right.

That's called evolving into a bilateral tonic -clonic seizure.

Okay.

So that's where the localized storm suddenly floods both hemispheres and they lose consciousness entirely.

Yes.

Which brings us to the second broad category,

generalized onset seizures.

Where the storm spreads widely throughout both hemispheres right from the very start.

Right.

And these almost always produce an immediate loss of consciousness.

The most recognizable is the tonic -clonic seizure.

That's the one with the severe muscle rigidity first, right?

The tonic phase.

Followed by synchronous muscle jerks, which is the clonic phase.

The patient might let out a loud cry as air is forcefully pushed across their vocal cords.

Ugh.

That sounds terrifying.

An incontinence is pretty common then too, right?

It is.

Afterward, they enter the postictal state, which is a period of severe central nervous system depression.

They're just exhausted and often sleep for hours.

You also mentioned absent seizures earlier, which are mostly seen in kids, right?

Yes.

Mostly in children.

Just rapid blinking or a blank stare for 10 to 30 seconds.

And they can have like hundreds of these a day?

Unfortunately, yes.

Up to hundreds a day.

Geez.

There are also atonic seizures, known as drop attacks.

That's a sudden, terrifying loss of muscle tone.

So they just collapse.

If it's just the neck muscles, their head violently drops.

If it's the whole body, they simply collapse to the floor.

That sounds so dangerous.

It really is.

Add to that myoclonic seizures, which are sudden one -second muscle contractions, and febrile seizures, which are fever -associated convulsions in young children.

I also read about Lennox -Gastaut and Dravet syndromes.

Those sound particularly devastating.

They are very severe childhood epilepsies.

They're characterized by developmental delays and just a chaotic mixture of different seizure types.

And they're hard to treat.

Very.

They are notoriously refractory, meaning they actively resist standard medical treatments.

So if we have highly localized focal seizures on one end of the spectrum and massive widespread generalized seizures on the other, does that mean we need totally different chemical weapons depending on the type of storm?

In most cases, yes.

This is a vital concept for nursing pharmacology.

Because what works for one might not work for another?

Exactly.

A drug that is highly effective for a focal seizure might be completely useless for an

Only a very small handful of drugs, like Valprod, have a broad enough spectrum to work across almost all types.

So accurate diagnosis is everything before you give that first pill.

Okay, so we know what the storm looks like.

But how do these drugs actually step in to stop it?

It's all about altering ion channels in neurotransmitters.

We have five basic mechanisms of action.

Okay, let's break those down.

What's the first one?

Mechanism one is suppressing sodium influx.

Normally, sodium rushes into the neuron to propagate an electrical signal.

So if the sodium channel is like a door letting the electrical signal in, the drug is basically jamming the deadbolt so the door stays shut longer.

You're on the right track.

By delaying the channel's recovery, the neuron physically cannot fire at the high frequencies required to sustain a seizure.

Makes sense.

And the second mechanism?

Mechanism two does something similar, but by suppressing calcium influx, which blocks transmission in the axon terminals.

Okay, so suppressing sodium and suppressing calcium, what's number three?

Mechanism three is the opposite,

promoting potassium efflux.

So instead of keeping something out, we are pushing something out.

Exactly.

Some drugs open potassium channels, letting positively charged potassium rush out of the neuron.

This hyperpolarizes the cell, slowing repetitive firing.

Okay, that covers the ions.

But then we have the neurotransmitters.

I know glutamate is the brain's main excitatory neurotransmitter, like the brain's gas pedal.

Right.

So mechanism four is antagonizing or blocking glutamate to ease off that gas pedal.

Got it.

And the last one?

Mechanism five is potentiating GABA.

GABA is the brain's main inhibitory neurotransmitter, is the brake pedal.

So enhancing GABA broadly decreases neuronal excitability.

Okay, that makes sense on a cellular level.

It does.

But zooming out to the actual patient, the therapeutic goal isn't just zero seizures at any cost.

Right.

Because if you hammer the brain's brake pedals hard enough, you stop the seizures, but you also stop the patient from being able to, like, stay awake.

That is the tightrope nurse's walk every day.

If we completely eliminate all seizures, the patient might be so heavily sated they can't go to school, work, or function.

So it's a balance.

Exactly.

Maximizing seizure control while keeping side effects tolerable so the patient can actually live their life.

And finding that balance requires constant monitoring of plasma drug levels.

But I found a really interesting clinical nuance here in the text.

Oh, what's that?

Well,

we meticulously monitor blood levels for tonic -clonic seizures, but apparently we don't rely on blood draws as much for absent seizures.

Why the difference?

It comes down to frequency and danger.

A tonic -clonic seizure is a massive dangerous event, but it might only happen once a month.

Right, so you can't just wait around to see if the drug is working.

Exactly.

You cannot afford to wait a month because the next seizure could be fatal.

So we draw blood to confirm the drug has reached a known therapeutic range.

But for absent seizures?

The child might be having a hundred minor episodes a day.

As a nurse, you don't necessarily need a lab value to tell you if the dose is working.

Because you can just watch them?

Yes.

You simply observe the patient in the clinic.

If the rapid blinking and blank stares stop,

your dose is sufficient.

That is a brilliant clinical pearl.

Now what about the hurdles?

What causes therapy to fail?

The biggest culprit, by far, is non -adherence.

It counts for about 50 % of all treatment failures.

Wow, 50%.

So just patient education is huge.

It's paramount.

Promoting adherence and having the patient keep a detailed seizure frequency chart is a primary nursing intervention.

And what's the other major hurdle?

Withdrawal.

Let me guess.

Patients feel better, stop taking the drug cold turkey,

and the storm comes back worse than ever.

Sadly,

yes.

Withdrawing these drugs must be done incredibly slowly, over weeks or even months.

And if they don't?

Abrupt withdrawal is a frequent cause of status epilepticus, which is a life -threatening continuous seizure.

Yikes.

Okay, there's another safety element I want to ask about.

I've seen FDA warnings that anti -seizure drugs can cause suicidal thoughts.

Yes, that warning was put on all of them back in 2008.

But the text suggests that might be, well, kind of an overreaction.

Is that accurate?

The 2008 data, painted with a very broad brush,

analyzing newer data suggests the statistically significant risk of suicide really applies mostly to two specific drugs.

To Pyramid and Lymotriging.

Oh, interesting.

Furthermore, many experts argue that the underlying illness, the heavy burden of living with epilepsy or pre -existing depression,

might be the true driver.

Rather than the medications themselves.

So as a nurse, how do you handle that conflicting data with a patient?

With deep prudence.

You don't dismiss the risk.

You screen all patients for depression before starting therapy, and you actively monitor them for increased anxiety, agitation, mania, and hostility.

Okay, let's talk about the evolution of these drugs.

The pharmacology world basically divides them into two eras.

The first -generation old guard and the new -generation wave.

Right, and there is a fundamental divide between them.

So what's the deal with the first -generation drugs like phenytoin and valparate?

Well, they have been around for decades.

We know exactly how effective they are, and they are inexpensive.

But they are notorious for complex pharmacokinetics, harsh side effects, and terrible drug interactions because they dramatically induce or inhibit liver enzymes.

And the new -generation drugs.

They are generally much better tolerated and have fewer interactions, but they are expensive, and our long -term clinical experience with them is still evolving.

Before we look at specific drugs, there is a massive overarching issue regarding pregnancy.

These drugs are known as peratogens.

They cause birth defects.

They do.

But pregnant patients are explicitly told not to stop taking them.

It sounds totally contradictory.

It really does, until you weigh the terrifying alternatives.

The teratogenic risk is very real.

But the risk from an uncontrolled maternal seizure is catastrophic.

Like it cuts off oxygen to the baby.

Exactly.

A severe seizure can cause fetal hypoxia, severe developmental damage, or result in a miscarriage.

The danger of the oxygen deprivation far outweighs the danger of the drug.

So how does a nurse manage a pregnant patient safely?

You collaborate with a provider to use the absolute lowest effective dose.

You try to use monotherapy, just one drug, instead of a combination.

And aren't you supposed to avoid valproate?

Absolutely, if possible.

It is highly teragenic and causes neural tube defects.

The nurse must also ensure the patient takes high dose daily folic acid.

I also read about a bleeding risk for the baby.

Yes, many of the Olgaard drugs induce liver enzymes that chew up vitamin K -dependent clotting factors.

So how do you fix that?

Protocols often require administering vitamin K to the pregnant patient in her final month and a vitamin K injection to the newborn immediately at birth.

And for patients who are not trying to get pregnant, we have to remember that many of these drugs decrease the effectiveness of oral contraceptives.

Absolutely.

The nurse has to have a frank conversation about alternative birth control.

OK, let's look at the Olgaard, starting with the prototype for the first generation, Finitoin.

Finitoin is a sodium channel blocker.

And its pharmacokinetics are famous for being incredibly tricky.

Right, the way it's metabolized.

Is it kind of like a busy highway where traffic is flowing fine at 65 miles per hour?

But the moment you add just one or two extra cars, the whole system hits a bottleneck and grinds to a dead stop.

That is a very accurate way to understand its saturation kinetics.

The liver enzymes that metabolize Finitoin get saturated rapidly.

So a tiny increase in the dose doesn't just bump the plasma level up slightly.

No, the drug accumulates exponentially because the liver simply cannot process any more of it.

So a patient could go straight into a toxic overdose.

Precisely.

The therapeutic range is narrow, 10 to 20 micrograms per milliliter.

If they cross into toxicity, you'll see neurological red flags.

Like what?

They stagnate, which is the continuous uncontrollable back and forth movement of the eyes,

ataxia, meaning they stagger when they walk, and severe cognitive impairment.

I know there are two other major patient teaching points for Finitoin.

First is gingival hyperplasia, where the gum tissue literally overgrows the teeth.

Yes, it happens in about 20 % of patients.

The nurse needs to teach them to take supplemental folic acid and maintain meticulous flossing to minimize it.

The second is a severe dermatologic risk.

Stevens -Johnson syndrome, or SJS, this life -threatening rash.

And there is a genetic component here, right?

A very strong one.

Product labeling warns that this SJS risk is linked to a genetic mutation called the

HLAB1502 gene.

And that's found mostly in specific populations.

Yes, almost exclusively in people of Asian descent.

So a nurse should expect to see genetic screening ordered before administering Finitoin to add risk populations.

What if a patient is crashing and we need to give Finitoin via IV?

You have to be incredibly careful.

Intravenous Finitoin is dangerous.

The absolute maximum infusion rate is 50 milligrams per minute in adults.

Any faster, and what happens?

You risk profound hypotension and cardiovascular collapse.

You can also only mix it with normal saline.

If you mix it with dextrose, it forms crystals in the line.

And you must watch the IV site constantly for extravasation.

If the drug leaks out of the vein into the tissue,

it causes severe tissue necrosis known as Purple Glove syndrome.

That sounds like an absolute nightmare.

Is that why phosphonitoin was developed?

Exactly.

Phosphonitoin is a prodrug that converts to Finitoin in the body, but it is much gentler on the veins.

And the main nursing alert there is just to remember it's dosed in PE or Finitoin equivalents, not standard milligrams.

Let's look at another first -generation heavy hitter, carbamazepine.

It's often the first choice for focal seizures because it's better tolerated than Finitoin, but it has its own dangers.

It does.

The big one is bone marrow suppression.

It can wipe out blood cell production.

So as a nurse, you're checking pleat blood counts or CBCs?

Routinely.

Looking for leukopenia, anemia, or thrombocytopenia.

It also promotes water retention, causing hyponatremia low sodium.

Which is bad for heart failure patients.

And doesn't it interact with grapefruit juice?

It does.

Dangerously so.

And it carries the exact same HLA -B5O52 -SJS rash risk as Finitoin.

Okay.

Then we have Valpro.

It's a broad -spectrum giant.

It works on both GABA and sodium channels, so it treats almost everything.

But the adverse effects are severe.

Severe and rapid.

Valpro carries a risk of fatal hepatotoxicity -level failure.

You have to be super careful with toddlers on this, right?

Extremely.

Imagine assessing a two -year -old on this drug.

You have to be hypervigilant for a sudden loss of appetite, lethargy, or a yellowing of the eyes.

In fact, you do not use this drug in children under two who are taking other anti -seizure medications.

It also causes pancreatitis, doesn't it?

Yes.

Rapidly fatal hemorrhagic pancreatitis.

You must teach patients that severe abdominal pain and vomiting are an immediate emergency.

Moving to ethosuximide.

This one seems pretty straightforward.

It is the silver bullet for absent seizures.

And only absent seizures.

It works beautifully by blocking those calcium channels we discussed earlier.

Lastly, for the old guard, we have phenobarbital and primidone.

Phenobarbital is a barbiturate.

Its claim to fame is suppressing seizures without causing total CNS depression.

But the drawback is its massive half -life.

It takes four full days to clear half the drug, meaning it takes weeks to reach a steady therapeutic level.

And it causes physical dependence too, right?

Yes.

And it's a massive inducer of drug metabolizing enzymes.

Also, if you give primidone, it actually metabolizes into phenobarbital in the body.

So the golden rule is you never prescribe them together.

Exactly.

Because of all these narrow margins, constant blood draws, and liver toxicities, science pivoted to the new generation drugs.

Let's run through some of these, starting with oxcarbazepine.

Oxcarbazepine is a newer derivative of carbamazepine, so it still blocks sodium channels.

The clinical picture is somewhat similar.

It causes clinically significant hyponatremia.

So you're monitoring serum sodium and assessing for nausea, headache, and confusion.

And it also carries the SJS genetic risk.

Yes.

But since it's newer, does it avoid all those massive enzyme interactions that chew up other drugs?

Mostly, yes.

It doesn't heavily induce the enzymes that metabolize other anti -seizure drugs, but, and this is a crucial patient teaching point, it still induces the enzymes that metabolize oral contraceptives.

So the alternative birth control rule still strictly applies.

What about some of the more unique new generation drugs?

I found the profile on cannabidiol or apidiolex fascinating.

Ah, yes.

The first cannabis -derived FDA drug, but it has zero psychoactive effects.

Right.

It won't get the patient high.

But its pharmacokinetics are heavily influenced by the stomach, aren't they?

Very much so.

Administrating it with a high -fat meal vastly increases its absorption.

So the nursing education here is consistency.

Absolutely.

The patient must always take it with food, or always without, otherwise their blood levels will swing wildly.

And what was that detail about feeding tubes?

Oh, if you are giving it via an enteral feeding tube, it requires specific silicone tubes.

If you use a standard polyurethane tube, the plastic actually absorbs the drug before it ever reaches the patient's stomach.

That is wild.

Speaking of wild side effects, ezogabein, this is the one that opens potassium channels to let potassium out of the neuron.

Yes, and it has a bizarre mechanism of toxicity.

Prolonged use causes bleak skin discoloration, particularly on the lips and nail beds.

And affects the eyes, too, right?

It does.

It binds to pigments in the eye, causing retinal abnormalities that can lead to permanent vision loss.

Wow.

Let's just rapid fire a few more key nursing alerts for the newer drugs.

Feldemit.

Black box warning for fatal aplastic anemia and liver failure.

Lamotrigine.

Broad spectrum, but high risk of life -threatening rash, especially if combined with Valprode.

Leviterostam or Kepra.

Unique MOA, and amazingly, zero pharmacokinetic interactions.

It's very safe to combine.

Nice.

What about vigabatrin and zonosamide?

Vigabatrin causes permanent vision loss, so it's heavily restricted via the SHARE program.

Zonosamide is a sulfonamide, so it's completely contraindicated for sulfur allergies, and it can cause kidney stones.

Okay.

Let's loop back to gabapentin.

I see this prescribed all the time for nerve pain, but it's classified here as an anti -seizure drug.

It enhances GAVA release.

The safety alert for nurses revolves around formulation confusion.

Neurontin is the version used for seizures.

And you can't just swap it with the others.

Absolutely not.

It is not interchangeable with extended release formulations like Raleigh's or Horizont, which are used strictly for nerve pain and restless leg syndrome.

Let's talk about lacosamide.

The text flags a cardiac issue.

It prolongs the PR interval on an EKG.

What does that actually mean for a patient lying in a hospital bed?

A prolonged PR interval means there is a dangerous delay in the electrical communication between the top and bottom chambers of the heart.

So if your patient already has cardiac conduction issues or an AV block, this drug could trigger a severe arrhythmia.

You use it with extreme caution.

Exactly.

What about parampanel?

I know it is an AMPA glutamate antagonist.

Wait, what does AMPA mean in this context?

AMPA is simply a specific type of receptor in the brain that glutamate binds to.

By blocking it, we stop glutamate from revving the brain's engine.

But the trade -off is psychiatric, isn't it?

Yes, it is severe.

Up to 20 % of patients experience extreme anger, hostility, and even homicidal ideation.

The nurse has to monitor their mood closely.

Wow.

Next is pregabalin, or Lyrica.

Why is this one listed as a Schedule V -controlled substance?

Because unlike most anti -seizure drugs, pregabalin can cause euphoria, so there is a real risk of abuse.

It also has a unique nursing alert for reproductive toxicity, right?

But specifically male -mediated?

Yes.

It causes fetal abnormalities in animal studies via the sperm, so men taking this drug must use condoms if they're partners of childbearing age.

Good to know.

Let's hit topiramé.

It's broad -spectrum, but the big red flag is metabolic acidosis.

How does a seizure drug make the blood acidic?

It alters kidney function.

Topiramid inhibits an enzyme in the kidneys, which causes the body to excrete too much bicarbonate in the urine.

So without enough bicarbonate to buffer the blood, the patient becomes acidotic.

Exactly.

Nurses must routinely monitor blood bicarb levels and watch for hyperventilation and fatigue.

Okay, those are the maintenance drugs, but what happens when the maintenance fails and the storm just won't stop?

That is a condition called status epilepticus.

Specifically,

generalized convulsive status epilepticus.

Meaning continuous tonic -clonic seizures lasting 20 to 30 minutes.

Yes.

The patient is unconscious, tachycardic, hypertensive, and desperately hypoxic.

It is a massive medical emergency that rapidly leads to permanent brain injury or death.

Time is literally brain tissue.

What is the immediate protocol?

You establish an IV, maintain ventilation, and your absolute goal is to terminate the seizure within five minutes.

And the first -line drug for that?

First -line treatment is an intravenous benzodiazepine, specifically lorazepam, because its effects last up to 72 hours.

So lorazepam is the fire extinguisher.

It puts out the immediate blaze.

But you still need to prevent the fire from reigniting, right?

Because lorazepam isn't a long -term solution.

Yes.

Once the benzodiazepine breaks the act of seizure, follow -up care requires administering an IV -loading dose of phenytoin or phosphenytoin.

To lay down, like, a long -term suppressive foam, so to speak, to keep the storm from returning.

That's a great analogy.

We have covered so much vital ground today.

But I want to leave you, our nursing student listener, with a final thought about the future of your profession.

It's an exciting time.

Think back to the HLAB 1502 gene screening we discussed for phenytoin and carbamazepine.

It represents a profound shift in medicine.

For decades, neurology and pharmacology relied on trial and error.

You give a drug, wait to see if it stops the seizures, and wait to see if the patient's liver fails or their skin blisters.

But because of pharmacogenomics, we are moving into an era where a simple swab of a patient's DNA will tell the nurse exactly which anti -seizure drug will work perfectly for their unique brain chemistry.

And which one will cause a fatal reaction.

The future of epilepsy care isn't just about barricading the doors of the neuron blindly.

It is written in our genes, allowing for truly personalized medicine.

It really is a fascinating time to be entering the field.

It really is.

We are learning how to read the electrical storm before it ever starts.

To you, the learner, mastering nursing pharmacology is incredibly hard work, but you are doing it and your future patients will be safer because of it.

A warm thank you from the Last Minute Lecture team for trusting us to guide this deep dive.

Keep studying and we'll see you next time.