Seizures Flashcards
Exam 3
Causes of seizures (6)
- Infection
- Neoplasm
- Head injury
- Heredity
- Toxic effects
- Metabolic disorder
Principle MOA of anti-seizure meds involve ________ and _______
voltage-operated ion channels and excitatory synaptic function
What are the 3 main MOA of AEDs?
- Modification of ion conductance - Na+, K+, Ca++
- Enhancing inhibition - GABA
- Inhibiting excitation - Glutamate
What are the 3 types of focal onset seizures?
- Focal aware - simple partial
- Focal impaired awareness - complex partial
- Focal to bilateral tonic-clonic - partial seizure secondarily generalized
What are the 5 types of generalized onset seizures?
- Generalized tonic-clonic (grand mal)
- Generalized absence (petite mal)
- Myoclonic
- Atonic/clonic (drop attack)
- Infantile spasms (West’s syndrome)
What are automatisms seen in complex focal seizures?
- Lip smacking
- Swallowing
- Fumbling
- Scratching
- Walking about
Focal seizures secondarily generalized look like _______ seizures
tonic clonic
Differentiate between focal and generalized seizures
Focal - begin in specific area of brain
Generalized - begin over entire surface of brain
Generalized tonic-clonic automatisms
- starts with aura
- Person falls to ground
- Entire body stiffens
- Muscles jerk or spasm
- Tongue or cheek may be bitten
- Urinary incontinence
Seizures where muscles suddenly contract and stiffen
tonic
Seizures where there is a sudden loss of muscle tone
atonic
Seizures that make the body jerk like it is being shocked
Clonic and myoclonic seizure
What age do infantile spasms begin?
Usually begins before age of 6 months
Phenytoin MOA
all - mainly Na+, gaba, and glutamate receptors
What is the more soluble prodrug of phenytoin that can be administered IV?
Fosphenytoin
What type of seizures is phenytoin used to treat?
Partial and tonic-clonic seizures
Which drugs compete with phenytoin for albumin binding sites?
Carbamazepine, sulfonamides, valporic acid
Which drug can displace phenytoin from albumin binding sites?
valporic acid
Differentiate between therapeutic, free, toxic, and lethal levels of phenytoin
- Therapeutic: 10-20 mcg/ml
- Free phenytoin: 1-2.5 mcg/ml
- Toxic: 30-50 mcg/ml
- Lethal: >100 mcg/ml
What is the T1/2 of phenytoin?
12-36 hours
What are the toxic effects of phenytoin?
- Nystagmus
- Loss of extraocular pursuit of movement
- Diplopia
- Ataxia
- Sedation
What are the toxic effects of phenytoin with chronic use?
- Gingival hyperplasia
- Hirsuitism
- Coarsening of facial features
Carbamazepine (Tegretol) MOA
Blocks Na+ channels
What kind of antidepressant is carbamazepine?
TCA
What is the clinical use for carbamazepine?
- Drug of choice for focal seizure
- Can be used with phenytoin
- Effective in trigeminal neuralgia
- Also useful for bipolar disorder
What is the drug of choice for a focal seizue?
Carbamazepine (Tegretol)
When does Carbamazepine (Tegretol) peak?
6-8 hours
Carbamazepine (Tegretol) is ___% bound to plasma proteins
70%
What is the T1/2 of Carbamazepine (Tegretol)?
T1/2 after one dose = 36 hours
T1/2 during continuous therapy = 20 hours
______ is an autoinducer of hepatic enzymes (P450) used to treat seizures
Carbamazepine (Tegretol)
What are the drug interactions for Carbamazepine (Tegretol)?
- Phenytoin
- Phenobarbital
- Ethosuxemide
- Valproic acid
- Clonazepam
What are the clinical uses for Lacosamide (Vimpat)?
focal seizures
What is the MOA of Lacosamide (Vimpat)?
Blocks sodium channels
What are the toxic effects of Lacosamide (Vimpat)?
- Dizziness, nausea, HA, diplopia
- Minimal drug interactions
The oldest and safest AED available is _____
phenobarbital
What is the MOA of Phenobarbital?
Unknown - Enhances inhibitory transmission (+ GABA), decreases excitatory transmission, may suppress abnormal neurons
What is the AED drug of choice for infants?
Phenobarbital
What are the clinical uses of Phenobarbital?
- Focal seizures
- Generalized tonic-clonic seizures
- Tried in virtually every seizure type
What seizure types can be made worse by phenobarbital?
Generalized seizures: absence, atonic attacks, or infantile spasms
What is the #1 toxic effect of phenobarbital?
SEDATION
What are symptoms of overdose of phenobarbital?
- unsteady gait
- slurred speech
- confusion
- respiratory depression
- coma
What type of seizures is Lacosamide used as an adjunct?
Focal seizure
What is the MOA of Lamotrigine? What kind of seizures can it treat?
MOA –ion channel; partial & absence
How can GABA analogs be used to treat seizures? What is an example?
adjunct, partial, neuralgia
(Vigabatrin)
What are the main 4 drugs used to treat focal and generalized tonic-clonic seizures?
Phenytoin
Carbamazepine
Lacosamide
Phenobarbital
How are infantile spasms treated?
palliative, steroids, Vigabatrin (GABA analog)
What are the 2 main drugs used to treat generalized seizures (not tonic-clonic)?
Ethosuzimide and Valproic acid
What is the drug of choice for absence seizures?
Ethosuximide
What is the MOA of Ethosuximide?
Calcium channel inhibition
What are the toxic effects of Ethosuximide?
Gastric distress (pain, N/V) and lethargy
What is the MOA of valproic acid?
Unknown, hypotheses: All
- Blocks sustained high frequency firing
- Effects on Na+ currents
- Increase GABA
- Increase membrane K+ conductance (high levels)
What is known as the “Broad spectrum AED”?
Valproic acid
What are the clinical uses of valproic acid?
- Absence seizures
- Some types of myoclonic seizures
- Generalized tonic-clonic
- Bipolar disorder
- Migraine prophylaxis
What are the Valproic acid toxic effects?
- GI
- N/V
- Pain
- Heartburn
What is the MOA of benzodiazepines?
Increased GABA – depresses all levels of the CNA
Diazepam (Valium) pharmacokinetics
Long T1/2 (20-100 H), short duration (30 min.)
What is the clinical use of benzodiazepines in seizure treatment?
Status epilepticus and absence
What are the 4 options for seizure treatment?
– Antiepileptic drugs
– Surgery
– Vagus nerve stimulation
– Ketogenic diet (children)
What is the most common form of status epilepticus seizures?
generalized tonic-clonic
What is the treatment for status epilepticus?
Sedation – IV (diazepam, fosphenytoin, phenobarb)
What are the drugs to avoid perioperatively that can stimulate seizure activity?
Methohexital, sevoflurane, meperidine (Demerol)
The only narcotic that stimulates seizure activity is ______
meperidine (Demerol)
What are the effects of phenytoin use on NMB?
Chronic phenytoin therapy makes patient resistant to neuromuscular blocking agents
Phenytoin can enhance NMB (acute)
