Lecture 46: Antiepileptics Flashcards Preview

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Flashcards in Lecture 46: Antiepileptics Deck (34):
1

Narrow-spectrum medications are useful for what kind of seizure? What two kinds are they not useful for?

Focal seizures; generalized tonic-clonic seizures and myoclonic seizures

2

Broad-spectrum medications are effective for...

Focal and generalized seizures

3

Name the narrow spectrum drugs (2)

Gabapentin**, tiagabine**

4

Name the broad spectrum drugs (6)

Phenytoin**, carbamazepine**, valproate**, topiramate*, levetiracetam*, lamotrigine*

5

What drug treats absence epilepsy?

Ethosuximide**

6

What drug treats status epilepticus?

Lorazepam*

7

Three most common mechanisms of antiepileptics

Inhibit VG-Na+, inhibit VG-Ca2+, enhance GABA

8

Why is the hippocampus predisposed to seizures? (2)

Excitatory positive feedback to CA3 neurons; densely packed neurons

9

An epilepsy linked to a genetic defect might have a defect where?

Channels (i.e. increased excitatory/reduced inhibitory currents through VG-channels)

10

How do AEDs inhibit Na* channels? Name them (5)

Stabilize inactive state of channel; Carbamazepine, valproate, topiramate, phenytoin, lamotrigine

11

How do AEDs enhance GABA signaling? Name them (3)

Allosterically at GABAa; Benzos, phenobarbital (barbituate), topiramate

12

Which AED increases synaptic levels of GABA? How?

Tigabine; blocks GABA reuptake

13

What channel underlies absence epilepsy? Where? Usually associated with?

Ca2+ channels in thalamocrotical neurons; sleep spindles

14

Which two drugs inhibit T-type Ca2+ channels, making them good at treating...

Ethosuximide and Valproate; absence seizures

15

What other drug can be used to treat absence seizures?

Clonazepam

16

Two drugs inhibit another type of Ca2+ channel. What are these drugs?

Lamotrigine and levetiracetam

17

Topiramate inhibits Na+ channels. What is another mechanism of its action?

Modulates AMPA receptors

18

According to LC, the mechanism of this drug is unknown. According to lecture, it increases K+ conductance. Drug?

Levetiracetam

19

Key note about Phenytoin and relevant SEs (acute: 3, chronic: 1)

Non-linear pharacokinetics in therapeutic window make window narrow; nystagmus, ataxia, hypersensitivity (Stevens-Johnson); gingival hyperplasia

20

Is phenobarital commonly prescribed? SE?

No! Was once widely prescribed AED; sedation

21

Carbamazepine comes with what important 3 warnings. Which are rare?

Rare: blood dyscrasias, Stevens-Johnson; hyponatremia

22

Tigabine has what common side effect?

Dizziness

23

What is the most widely used AED, worldwide? Describe its clinical use

Valproate; Can be used for general, partial, absence AND myoclonic

24

Topiramate's other uses and some SEs

Headache, alcoholism, tremor, obesity...paresthesias in 30%

25

While the mechanism fr this drug is unknown, it has some advantages...what are those?

Levetiracetam; does not induced liver enzymes and is well-tolerated

26

When you see Ethosuximide, think about this seizure type. How is it tolerated?

Absence; well

27

Four specific adverse events in AEDs

Serious hypersensitivity reactions, cognitive slowing, sedation, seizure induction

28

Which two drugs are associated with malformations in pregnancy?

Valproate and phenobarbital

29

What warning do all AEDs bear?

Increased suicide risk

30

Describe status epilepticus treatment (5 steps)

1. Start ASAP to protect neurons; 2. Begin w/ benzos; 3. Give phenytoin to prevent recurrence; 4. If not controlled, give phenobarbital or valproate; 5. If still not, induce general ansethesia

31

Induction

Drug A increases enzyme for Drug B --> Drug B eliminated faster

32

Competition

Drug A and Drug B are substrates for same enzyme --> Drug B eliminated slower

33

Inhibition

Drug A inhibits enzyme for Drug B --> Drug B eliminate slower

34

Which pharmacokinetic interaction is important for AEDs? Which enzymes? Which drugs?

Induction; CYP450; phenytoin, carbamazepine, phenobarbital

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