Exam 1 - Antiepileptics Flashcards

1
Q

What are the three partial/focal seizures and which is associated with impairment of consciousness?

A

simple partial (without), complex partial (with) and secondary generalized

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2
Q

Explain pathophysiology of seizures?

A

abnormalities in ion channel, increased ENT activity, rhythmic and repetitive hypersynchronous discharge of neurons, seizure focus

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3
Q

What seizures is phenytoin used for? (2)

A

partial and generalized tonic-clonic

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4
Q

Explain phenytoin pharmacokinetics? (6)

A

80-90% protein bound, inducer, t1/2 = 20 hrs, TPI = 10-20 ug/mL, 200-400 mg/day, excreted in urine

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5
Q

What is the MOA for phenytoin?

A

membrane stabilization by blocking Na and Ca influx

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6
Q

What are adverse effects of phenytoin?

A

gingival hyperplasia, hirsutism, osteomalacia, Hydantoin syndrome

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7
Q

What drug has a similar MOA and clinical uses (+mania and trigeminal neuralgia) as phenytoin?

A

carbamazepine

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8
Q

Explain carbamazepine pharmacokinetics? (6)

A

80% protein bound, strong inducing agent, t1/2 = 30 hrs, TPI = 6-12 mg/mL, 200-800 mg/day, excreted in urine

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9
Q

What are adverse effects of carbamazepine?

A

congenital malformation, hyponatremia and water intoxication, blood dyscrasias (fetal aplastic anemia)

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10
Q

Explain valproate pharmacokinetics? (2)

A

t1/2 = 15 hrs, excreted in urine

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11
Q

What seizures is sodium valproate used for? (2)

A

absence, myoclonic

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12
Q

What are adverse effects of sodium valproate?

A

increased appetite and weight gain, hepatotoxicity, neural tube defects

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13
Q

What is the MOA for levetiracetam?

A

non-competitive AMPA receptor antagonist

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14
Q

What seizures is levetiracetam used for?

A

all

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15
Q

What is the dosing for immediate release levetiracetam?

A

500 mg bid

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16
Q

What is the dosing for extended release levetiracetam?

A

1 g qd

17
Q

Explain pharmacokinetics for lamotrigine? (3)

A

does not affect hepatic enzymes, t1/2 = 24 hrs, excreted in urine

18
Q

What is the MOA for lamotrigine?

A

inhibits amino acid release by Na channel blockade

19
Q

What are adverse effects of lamotrigine?

A

rash, somnolence

20
Q

What is the MOA of gabapentin?

A

structural analogue of GABA

21
Q

Explain pharmacokinetics for lamotrigine? (4)

A

not protein bound, does not affect hepatic enzymes, t1/2 = 5-7 hrs, excreted unchanged in urine

22
Q

What seizures is gabapentin used for?

A

adjunct with other antiepileptics

23
Q

What are adverse effects of gabapentin?

A

somnolence, ataxia, nystagmus

24
Q

Explain pharmacokinetics of topiramate? (4)

A

9-17% protein bound, does not affect hepatic enzymes, t1/2 = 18-24 hrs, excreted unchanged in urine

25
Q

What is the MOA of topiramate?

A

blocks sodium channels

26
Q

What are adverse effects of topiramate?

A

psychological or cognitive dysfunction (“dopamax”), weight loss, urolithiasis, bilateral paresthesias

27
Q

Explain pharmacokinetics of vigabatrin? (4)

A

not protein bound, does not affect hepatic enzymes, t1/2 = 4-7 hrs, excreted unchanged in urine

28
Q

What is the MOA for vigabatrin?

A

inhibits GABA metabolizing enzyme

29
Q

What seizures is vigabatrin used for?

A

infantile spasms

30
Q

What are adverse effects of vigabatrin?

A

visual field defects, psychosis, and depression

31
Q

Explain pharmacokinetics of zonisamide? (4)

A

40% protein bound, does not affect hepatic enzymes, t1/2 = 50-68 hrs, metabolized by liver

32
Q

What is the MOA for zonisamide?

A

prolongation of sodium channel inactivation

33
Q

What seizures is zonisamide used for?

A

add-on therapy for partial seizures

34
Q

What are adverse effects of zonisamide?

A

drowsiness, ataxia, headache, N/V

35
Q

Explain pharmacokinetics of tiagabine? (3)

A

96% protein bound, t1/2 = 4-7 hrs, metabolized by liver

36
Q

What is the MOA of tiagabine?

A

inhibits GABA uptake

37
Q

What are adverse effects of tiagabine?

A

asthenia, sedation, dizziness, mild memory impairment

38
Q

What are reasons for failure of antiepileptics? (4)

A

improper diagnosis, incorrect drug, inadequate dose, compliance