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Pharmacology Exam 6 > Seizures and Epilepsy > Flashcards

Seizures and Epilepsy Flashcards

1
Q

Neurons

A

The functional unit of the brain

Extraordinarily complex network of billions of nerve cells

Communicate using electrical potentials

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2
Q

Action Potentials

A

Series of channels that selectively let charged elements in and out of cells

Channels for Na, K and Ca are particular important in seizures

All or nothing

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3
Q

Neurotransmitters

A

complex compounds that signal neighboring cells on or off

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4
Q

What is a seizure?

A

Seizure: a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain

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5
Q

Types of Seizures

A

convulsive (generalized, shaking)

non convulsive

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6
Q

Generalized seizures

A

typical of genetic causes and usually diagnosed in childhood

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7
Q

Seizure semiology – “the study of signs”

A

Most seizures (adults) start as a focal seizure

Partial seizures (start in small part of brain) ↔️ complex partial seizures causing confusion ↔️ secondarily generalized seizures (convulsive)

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8
Q

The First Seizure

A

Is it a seizure? (Any provoking cause)

MRI or CT

EEG or brain wave testing

Everyone can have a seizure - was it provoked

Patient with first unprovoked seizure: normal imaging and EEG – most neurologist DO NOT prescribe daily prophylactic medication

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9
Q

If second seizure occurs…

A

…likelihood of third seizure very high

start daily medications!

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10
Q

Epilepsy

A

At least two unprovoked seizures occurring greater than 24 hours apart

Young children may have genetic causes of epilepsy, Some are outgrown

Incidence of epilepsy is roughly 1% of the population

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11
Q

Cause of Epilepsy

A

Varies by age

most adults have lesional epilepsy

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12
Q

Long Term Care for Epilepsy

A

Months to years: trial and error period (to find ideal medication)

Patient care giver support is essential, care giver burden is tremendously high

Minimizing risk of injuries – swimming and bathing are particularly dangerous. Heights are also worrisome.

Many people have concurrent psychiatric and/or substance abuse disease and history.

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13
Q

Treatment of Epilepsy

A

Uncontrolled epilepsy is a severely disabling condition impacting all facets of life

Impairs ability to work, develop relationships and has a rather severe and destructive impact on psychiatric health

Patients who have had a seizure should not be driving until 1 year seizure free

First line therapy for epilepsy is medical to prevent ongoing seizures

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14
Q

Lorazepam (Ativan)

A

USE: FIRST LINE treatment in emergency seizure treatment (in ER or ambulance)

Not rapidly redistributed into tissue (half life is 24 hrs)

Rapid onset and Strong sedative

Not practical for daily use, can lead to withdrawal seizures with long term use

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15
Q

Midazolam (Versed)

A

USE: continuous infusion in ICU for severe/prolonged seizures

Very rapid onset (IV)

Half life 2 hours

Very strong sedative, most patients in ventilator while receiving drug

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16
Q

Clonazepam (Klonopin)

A

MOA: Work by facilitation of GABA mediated inhibition

USE: Some efficacy with all seizures, particularly useful in myoclonic types

AE: sedation, slow cognition, drooling

Watch for tolerance

Half life 24-48 hours

17
Q

Clobazam (Onfi)

A

MOA: GABAA receptor agonist

USE: approved in last 5 years here in the US for Lennox-Gastaut syndrome, Adjunctive, “add on” therapy

Half life 10-46 hours

Dosed twice daily

Tolerance common, may need escalating doses to maintain control

18
Q

Phenobarbital (Luminal)

A

MOA: Prolongs the open state of the GABA receptor, depresses normal excitatory activity

Most drug eliminated by liver, half life is 70-130 hours

Strong enzyme inducer

AE: sedation, confusion, insomnia, interferes with Vitamin D metabolism, very high risk of withdrawal

19
Q

Primidone (Mysoline)

A

MOA: Metabolized to phenobarbital

USE: drug itself may also have anti seizure properties, tremor

AE: similar to phenobarbital

20
Q

Phenytoin (Dilantin)

A

MOA: membrane stabilizing effect, multiple actions sites on Na channels, extensively protein bound, inducer of P450 system

USE: status epilepticus

Complicated first order and zero order

AE: cerebellar atrophy, sensory neuropathy, gingival hyperplasia, bone density loss (due to altered metabolism of vitamin D), risk of serious arrhythmia and bradycardia during IV administration

Drug interactions: phenobarbital, carbamazepine and valproic acid

21
Q

Carbamazepine (Tegretol, Carbatrol ER)

A

MOA: stabilizing effect on membrane, particularly related to Na currents

USE: Focal onset seizures

Strong hepatic enzyme inducer with clinically significant drug-drug interactions

AE: GI upset, allergic reactions, and persistent leukopenia with long term usage

22
Q

Oxcarbazepine (trileptal)

A

MOA: similar to carbamazepine

USE: focal onset seizures

AE: allergic reactions and hyponatremia

Better tolerated than carbamazepine, fewer drug-drug interactions

No IV

23
Q

Lamotrigine (Lamictal)

A

MOA: similar to phenytoin and carbamazepine, voltage dependent blockade of Na channels

USE: all seizure types with exception of myoclonic seizures

AE: Stevens-Johnson’s Syndrome, can be life threatening

Start at very low doses to limit likelihood of skin reactions → Escalate over a period of weeks to months.

Not a good choice for patients with poor compliance

24
Q

Topiramate (Topamax)

A

MOA: inhibits voltage activated Na channels, decreases glutamate-mediated excitatory transmission, also effects Ca currents, GABA mediated channels and as weak inhibitory CA activity.

USE: some efficacy against all seizure types, also commonly used in migraine, psychiatry and neuropathic pain

AE: cognitive slowing, word finding difficulty, renal stones, weight loss

25
Q

Valproic acid, Divalproex (Depakote, Depakene)

A

MOA: increase GABA concentrations, modulate GABA receptor expression on cell surfaces. Some metabolites also active.

P450 enzyme inhibitor

USE: primary generalized seizures (think JME), effective in absence and myoclonic seizures. Less effective for focal onset.

prolongs half life of lamotrigine, may act synergistically

AE: weight gain, tremor, alopecia, hyperammonemia with encephalopathy, platelet function, PCOS, major risk of teratogenicity

Risk for hepatic failure in children under 10, especially those with certain genetic conditions.

26
Q

Gabapentin (Neurontin)

A

MOA: Unique binding site in neocortex and hippocampus voltage gated Ca channel

USE: partial onset seizures, “weak” anti seizure drug, add on for patients with neuropathic pain and seizures

AE: drowsiness, dizziness and sensory changes

27
Q

Levetiracetam (Keppra)

A

MOA: binds to synaptic vesicle protein 2a, unclear how this is effective

USE: non-neurologists for seizures, all seizure types and may be particularly useful in temporal lobe epilepsy

AE: agitation or mood changes, concern in patients with underlying psychiatric disease

Well tolerated and has no drug interactions

28
Q

Ethosuximide (Zarontin)

A

MOA: module Ca channels in the thalamus

USE: exclusively in absence seizures

AE: GI disturbance , very safe, can worsen non-absence seizures

29
Q

Vigabatrin (Sabril)

A

MOA: Irreversible inhibitor of GABA transaminase, long acting drug

USE: infantile spasms

AE: retinal toxicity manifested as concentric visual field constriction

Limits use for a duration of 6 months

Imperative baseline visual field and follow ups

30
Q

Cannabidiol (Epidiolex)

A

MOA: Low affinity for CB1 and CB2 receptors, Serotonergic

USE: Dravet Syndrome and LGS

No psychotropic properties

AE: GI and liver side effects most common

31
Q

Status Epilepticus

A

True neurological emergency

Seizures lasting longer than 5 minutes with or without rescue therapy and unlikely to spontaneously terminate

Need respiratory support (intubation) and ICU level care

Rapid and aggressive medication adjustments

32
Q

Medications During prolonged Seizures

A

Rescue vs prophylactic medication

IV preferable, can give IM as well

If seizure does not terminate repeat

Continue benzodiazepine administration while preparing ‘prophylactic’ medication

Plan to intubate patient

33
Q

Dosing

A

Depends on half life

Drugs with long half-life (phenytoin, phenobarbital) can be given once a day

Drugs with short half-life (valproate, carbamazepine) require more frequent dosing

The less frequent the dose, the greater the compliance

34
Q

Enzyme Induction

A

A subset of the p450 isoenzymes (1C2, 2C9, 2C19, 3A4) and uridine glucuronal transferase (UGT) are upregulated by phenytoin, phenobarb, primidone and carbamazepine

an increased rate of clearance for all compounds that utilize this pathway

35
Q

Enzyme Inhibition

A

Results in a decreased rate of drug clearance

Usually affect only one or two pathways = Depakote

More rapid effect than enzyme inducers

Pharmacology Exam 6 (5 decks)

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