Cns Pharmacology: Antiseizure Drugs

Front 1

In what regions do partial seizures often originate?

Back 1

regions of anatomic abnormality

-brain tumors
-AVMs
-trauma
-stroke

Front 2

How do simple partial and complex partial seizures differ regarding loss of consciousness?

Back 2

Simple partial: NO loss of consciousness

Complex partial: impaired or complete loss of consciousness

Front 3

Describe the category of seizure "partial with secondarily generalized seizures".

Back 3

The category consists of either simple partial or complex partial that progresses to generalized tonic-clonic activity.

(This is in contrast to generalized tonic-clonic seizures, which are NOT preceded by a partial seizure.)

Rhythmic contractions of arms and legs seen with tonic clonic seizures.

Front 4

Compare origins of partial and generalized seizures.

Back 4

Partial seizure: focal; originate in area of anatomic abnormality

Complex seizure: global; neocortical origin; synchronize with discharges in thalamus

Front 5

Describe onset and duration of absence generalized seizures.

Back 5

-abrupt onset
-duration less than 30sec
-impaired consciousness

Front 6

Describe manifestation of myoclonic generalized seizures.

Which drug is most effective in treating myoclonic seizures?

Back 6

-shocklike contraction of muscles
-can be generalized or localized

Valproate is the drug of choice for myoclonic seizures.

Front 7

Are tonic-clonic generalized seizures preceded by a partial seizure?

Back 7

No.

This is important to understand since the category "partial with secondarily generalized seizures" are those in which a partial seizure progresses to tonic-clonic activity.

Front 8

Consider a patient who has been on an antiseizure medication for 2 months. She is still having seizures, although less frequently. What is your clinical course of action with this incompletely controlled patient?

a) immediately add a 2nd antiseizure medication
b) giver her a prescription for the maximal dose of the current medication she is taking
c) tell her there's nothing else you can do

Back 8

b) try maximal dose of the current prescription

(another appropriate action would be to switch the patient's medicine to a different one... the point of this flashcard is so that you understand that you should not add a 2nd drug without trying other options)

Front 9

Phenytoin is effective in treating which 2 categories of seizures?

Which category of seizures does phenytoin exacerabte?

Back 9

Effective treatment for: parital seizures & generalized tonic-clonic seizures

Exacerabtes absence seizures

Front 10

Describe the toxic effects of phenytoin on:

(1) eye
(2) head/neck

Back 10

(1) eye: nystagmus; if frank dipolpia requires dosage reduction

(2) Head/neck: hirsuitism, gingival hyperplasia, "facial coarsening"

Front 11

Drug Interactions

Which drugs decrease phenytoin levels?

Which drugs increase phenytoin levels?

Back 11

Cause decreased phenytoin levels: phenobarbital, carbamazepine

Cause increased phenytoin levels: sulfonamides, phenylbutazone

Front 12

Describe the teratogenicity effects of phenytoin.

Back 12

Phenytoin may cause fetal hydantoin syndrome.

-mental retardation
-flat nasal ridge
-epicanthic folds
-hypertelorism
-prominent upper lip

Front 13

This is the drug of choice for partial seizures. This drug is also effective at treating tonic-clonic seizures as well as mood stabilization.

Back 13

Carbamazepine

Front 14

What are the hematologic toxic effects of carbamazepine?

Back 14

-mild leukopenia is common but often not a problem

-aplastic anemia is rare but potentially fatal

Front 15

What are the CNS toxic effects of carbamazepine?

Back 15

-diplopia
-ataxia

Front 16

This drug can be used as a treatment for generalized myoclonic seizures as well as for migraine prophylaxis.

Back 16

Valproate

Front 17

How does valproate affect phenytoin levles?

Back 17

Valproate inhibits metabolism of phenytoin because it competes for hepatic metabolism.

Front 18

Your patient is experiencing what you determine are shocklike muscle contractions. He is having them frequently. What should you prescribe?

Back 18

Your patient is experiencing myoclonic seizures.
Valproate would be the best choice for this patient.

Front 19

What significant GI toxic effect can valproate produce?

Back 19

Hepatotoxicity - it is uncommon but its severe

Front 20

Your patient is taking topiramate as treatment for her partial seizures. What toxic effects would indicate that she must come off of the medicine?

Back 20

glaucoma with vision changes warrants drug withdrawal

Front 21

Which antiseizure medication is approved as an adjunct for treatment of partial seizures in patients >16yo?

Back 21

Lamotrigine

Front 22

Describe the toxic effects of lamotrigine.

Back 22

Stevens-Johnson syndrome: less than 30% of body is affected

Toxic epidermal necrolysis: more than 30% of body is affected

Lamotrigine is contraindicated in patients under the age of 16yo.

Front 23

This antiseizure medication can be used as an adjunct for treatment of refractory partial seizures. It sometimes causes somnolence, psychosis, rashes, and renal calculi.

Back 23

Zonisamide

Front 24

What is the mechanism of phenobarbital?

Back 24

enhances GABA-mediated chloride flux

Front 25

Your patient has a history of partial seizures and she has been taking tigabine for a while. Your patient has a slight tremor, which is a major side effect. What other toxic effect could become apparent -- which would force you to withdrawal the drug?

Back 25

psychosis warrants tigabine withdrawal

Front 26

These 2 antiseizure drugs can treat postherpetic neuralgia.

Back 26

Gabapentin (increases presynaptic GABA concentrations)

Carbamazepine (potentiates GABA postsynpatic receptors & stabilizes inactive form of Na channel)


(note: mechanism are included in parentheses for completeness)

Front 27

This antiseizure drug exclusively blocks voltage-gated channels in the thalamus. It is the first-line drug for absence seizures.

Back 27

Ethosuximide

Front 28

What is status epilepticus?
How do you stop it?

Back 28

It is continuous tonic-clonic seizures & requires respiratory & cardiovascular support.

Treat with IV diazepam followed by IV phenytoin.

Front 29

Name the appropriate drug:

(1) Drug of choice for partial seizures
(2)Drug of choice for myoclonic seizures
(3)First-line drug in most kinds of seizures
(4)These 2 drugs treat neuropathic pain
(5)First-line drug for absence seizures
(6)Treats generalized tonic-clonic seizures but exacerbates absence seizures

Back 29

(1)Carbamazepine: partial seizures

(2)Valproate: myoclonic seizures

(3)Phenobarbital: first line for most seizures

(4)Gabapentin & carbamazepine: neuropathic pain

(5)Ethosuximide: absence seizures

(6)Phenytoin: treats tonic-clonic but exacerabates absence seizures

Front 30

Define epilepsy.

Define seizure.

Back 30

Epilepsy: symptom complex characterized by chronic, intermittent seizures

Seizure: self-limited episode of brain dysfunction

Front 31

What are the 6 anti-seizure drugs discussed that inhibit voltage-gated Na channels?

Back 31

1) phenytoin
2) carbamazepine
3) valproate
4) topiramate
5) lamotrigine
6) zonisamide