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Flashcards in Seizures Deck (71):
1

Causes of seizures

Congenital defects (cerebral palsy)
Hypoxia
Trauma (incl. brain surgery)
Cancer (tumors)
Alcohol or drugs (incl. withdrawal)
Elevated body temp (febrile)
Electrolyte disturbances
Drugs: Meperidine

2

Partial seizures

Simple
Complex
Secondarily generalized

3

Generalized seizures

Absence
Tonic
Clonic
Tonic-clonic (grand mal)
Myoclonic
Atonic

4

Seizure type guidelines

Identification is very important
Initial drug choice depends on what type
If you give the wrong med you could induce MORE seizures

5

Meds for all partial seizures

Valproate**
Carbamazepine
Phenytoin

6

Meds for generalized tonic-clonic

Valproate**
Carbamezepine
Phenytoin

7

Meds for absence seizures

Valproate

8

Meds for myoclonic seizures

Valproate

9

Meds for atonic seizures

Valproate

10

Anti-epileptic drugs (AEDs)

Most pts respond to 1-2 AEDs
Rarely do they require more than 2

11

What % of pts are controlled with AED monotherapy?

50-70%

12

What % of pts require combination AED therapy

30%

13

What % of pts are poorly controlled despite AED therapy

5%

14

Pseudoresistance to AEDs

Wrong diagnosis
Wrong drug(s)
Wrong dose
Lifestyle issues (compliance, alcohol, drugs)
**MUST be ruled out to consider tx failure

15

Goals of AED therapy

Prevent seizures
Maintain normal function
Improve quality of life
**All w/ fewest side effects

16

Principle of AED therapy

Select recommended drug for seizure type

17

When augmenting AED therapy, what should you do?

Choose a drug w/ an alternative mechanism

18

When do you start AED therapy?

Depends on the pt
Rarely needed after single episode
Start in pts at risk for recurrent seizures
Generally start after >2 unprovoked seizures

19

Is AED therapy lifelong?

Not necessarily

20

AED withdrawal

Should be gradual/tapered
Sudden could lead to status epilepticus

21

When is AED relapse more likely

When withdrawn over 1-3 months

22

When is AED relapse less likely

If withdrawn over 6 months

23

What 2 standalone drugs do AEDs interact with?

Oral contraceptives
Warfarin

24

Significant CYP450 inducers

Phenytoin (Phenobarbital)
Carbamezepine
Primidone

25

Less significant CYP450 inducers

Oxycarbazepine
Topiramate

26

Much less significant CYP450 inducers

Newer (2nd generation) agents

27

Common AED side effects

Suicidal ideation (2 fold risk over general population)
CNS issues
Osteomalacia
Osteoporosis
Vision changes
Correlate drug levels to sx before changing meds

28

CNS side effects

Slowed thinking
Sedation
Ataxia
Dizziness

29

Why is AED monotherapy preferred

Increases adherence
Provides wider therapeutic index
More cost effective

30

Combination AED therapy guidelines

Combinations promote drug-drug interactions
No controlled studies comparing drug combos
Choose add-on w/ different MOA and/or SE profile

31

Big 3 AED meds

Phenytoin
Carbamezepine
Valproic acid

32

Phenytoin

IV or PO dosing

33

SE of phenytoin

Gingival hyperplasia
Rash
Acne
Nystagmus
Hirsutism
Osteomalacia
Folate deficiency

34

Carbamazepine

PO
SE: hyponatremia
Advantage = less cognitive impairment

35

Valproic Acid

IV and PO dosing
SE: fatal hepatotoxicity

36

Divalproex

Derivative of valproic acid
Depakote, Depakote ER
1:1 dimer in enteric coated tablet
Less GI effects

37

Phenobarbital

Rarely used except for in pregnancy
More SE than other drugs
Abrupt stopping may cause seizures
Taper slowly
Primidone -> metabolized to phenobarbitol

38

Benzodiazepines for seizures

Long term use not practical due to tolerance

39

Benzo agents for seizures

Clonazepam
Diazepam
Lorazepam

40

Agent for absence seizures

Ethosuximide

41

Felbamate

Use cautiously
Can cause fatal aplastic anemia and hepatotoxicity

42

Topiramate

Can cause temporary or permanent vision loss
Decreases sweating

43

Zonisamide

Chronic side effects similar to topiramate

44

Levetiracetam

Newer agent
Few drug interactions
IV and PO dosing

45

Gabapentin and Pregabalin

GABA analog
No interactions
Not first line AED

46

What AED do you give in pregnancy

Phenobarbital-D
*Anticonvulsant of choice during pregnancy*
Apparently this isn't true

47

American Academy of Neurology stance on generic stubsitution

Opposes generic substitution of anticonvulsant drugs for tx of epilepsy w/o physician approval

48

What AEDs are used for neuropathic pain

Gabapentin
Pregabalin

49

Other uses for AEDs

Bipolar disorder
Migraine

50

Status Epilepticus

Life-threatening emergency
Mortality = 20%

51

Status etiology

AED noncompliance/discontinuation
Withdrawal syndromes (alcohol/barbiturates)
Brain injury (tumor/stroke)
Metabolic abnormalities (decreased glucose, Na, Ca, Mg, etc.)
Drug use/overdoes that lowers seizures threshold

52

Drugs that lower seizure threshold

Imipenem
High dose penicillin G (IV PCN)
Lidocaine

53

Tx of status

Diazepam
Lorazepam
Phenytoin
Fosphenytoin
Phenobarbital

54

Diazepam for status

Inject directly -> diluting causes precipitation
Typically provides 30-40 minute seizure free interval
(often <20 mins due to redistribution into adipose)

55

Advantages of lorazepam for status

More effective than phenytoin
Easier to use than diazepam + phenytoin or phenobarbitol

56

Lorazepam for status

Most effective in terminating seizures w/in 20 mins and maintaining seizure free state in first 60 mins after tx
Longer lasting than diazepam
May be diluted w/ equal volume of 0.8% NaCl

57

Phenytoin for status

15-20 mg/kg IV load (better results at higher end 18-20)
Infuse no faster than 50 mg/min (may need to slow if pt becomes hypotensive)

58

Fosphenytoin for status

Pro-drug of phenytoin

59

How is fosphenytoin dosed?

Phenytoin equivalents (PEs)

60

How many mgs of fosphenytoin to phenytoin?

1.5 mg fosphenytoin to 1 mg phenytoin

61

Can you infuse fosphenytoin faster or slower than phenytoin

Faster
150 mg/min

62

Advantage of fosphhenytoin

Highly water soluble so it likely won't precipitate
Allows for IM administration
Less hypotension
Can be mixed in any solution

63

Phenobarbital dosing for status

If refractory:
IV 15-20 mg/kg @ 50 mg/min

64

Phenobarbital for status

Not 1st line due to: Slow administration
Prolonged sedation (half life 80-100 hours)
Greater risk of hypotension and hypoventilation
Little used -> not quickly available

65

How much folate do you supplement in young females on AEDs

1-4 mg/day

66

Who should you contact if you have questions about a pregnant pt on AEDs

AED Pregnancy registry

67

When do you discontinue AEDs?

Depends on seizure type, seizure free duration, EEG, etc.

68

Do you abruptly stop AEDs?

NO!!!

69

What does optimal AED tx require?

INDIVIDUALIZATION

70

% of fetal malformations w/ Levetiracetam (Keppra®)

2.4%

71

% of fetal malformations w/ Lamotrigine (Lamictal®)

2.0%