E1: Anticonvulsants Flashcards

1
Q

What is the main goal of anticonvulsants?

A

Since a blockage of GABA receptors causes seizures, the goal is to increase GABA activity
-OR since activation of glutamate can lead to seizures, the goal is to decrease glutamate activity

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2
Q

What are the 4 mechanisms in which anticonvulsants can increase GABA activity?

A
  • block GABA re-uptake
  • inhibit GABA metabolism
  • Stimulate GABA receptors
  • Binds synaptic vesicular protein
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3
Q

What are the two main channels that are inhibited by decreased glutamate activity?

A

Na+ and Ca+ channels

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4
Q

What are the three anticonvulsants that induce CYP450?

A

Phenytoin, Carbamazepine, and phenobarbital

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5
Q

What are the uses of phenytoin and fosphenytoin?

A
  • Partial seizures and generalized tonic-clonic seizures.

- Not effective of absence seizures

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6
Q

What is the MOA of Phenytoin and Fosphenytoin?

A

Prolongs inactivation of Na Channels by decreasing glutamate activity

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7
Q

Can phenytoin or fosphenytoin be injected?

A

Fosphenytoin

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8
Q

How is Phenytoin and fosphenytoin elimated?

A

-Elimination is 1st order at low doses and zero order at therapeutic and higher doses

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9
Q

What are the common side effects of Phenytoin?

A
  • Gingival hyperplasia
  • nystagmus, diplopia, ataxia, sedation
  • skin rash (risk of SJS)
  • Pregnancy category D
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10
Q

What is the DOC for partial seizures?

A

Carbamazepine

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11
Q

What are the uses of Carbamazepine?

A
  • DOC for partial seizures
  • generalized tonic-clonic seizures
  • Bipolar disorder
  • Trigeminal neuralgia
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12
Q

What is the MOA of Carbamazepine?

A

-Blocks Na channels by decreasing glutamate activity

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13
Q

What are the important pharmacokinetics associated with carbamazepine?

A
  • Induces CYP450

- induces its own metabolism

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14
Q

What are the drug interactions associated with Carbamazepine?

A
  • Increases metabolism of multiple anticonvulsants, haloperidol, and oral contraceptives
  • metabolism increased by phenobarbital and phenytoin
  • metabolism is inhibited by cimetidine, fluoxetine, and Valproic acid
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15
Q

What are the common side effects associated with carbamazepine?

A
  • SJS (test for HLA-B gene)
  • diplopia, ataxia, GI upset, drowsiness, aplastic anemia, and agranulocytosis
  • Pregnancy category D
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16
Q

What is the MOA of Lamotrigine?

A

-inactivation of Na channels by decreasing glutamate activity

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17
Q

What are the uses of lamotrigine?

A
  • partial seizures
  • may be effective against myoclonic and absence seizures in children
  • bipolar disorder
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18
Q

What are the important pharmacokinetics associated with lamotrigine?

A
  • inducers of CYP450 will increase metabolism

- half life is doubled by valproic acid

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19
Q

What are the common side effects of lamotrigine?

A
  • CNS (dizziness, headache, ataxia, diplopia)
  • nausea and vomiting
  • SJS
  • Pregnancy category C
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20
Q

What are the uses of Topiramate?

A
  • Partial and generalized tonic clinic seizures
  • may also be effective for absence seizures
  • migraine prevention
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21
Q

What is the MOA of Topiramate?

A

Blocks Na channels by decreasing glutamate activity

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22
Q

What are the common side effects of Topiramate?

A
  • acute myopia and glaucoma

- dizziness, sedation, nervousness, confusion

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23
Q

What are the uses of Levetiracetam?

A

-Partial, myoclonic, and tonic clonic seizures

24
Q

What is the MOA of Levetiracetam?

A

-Binds to synaptic vesicular protein (SV2A) and appears to decreased glutamate and increase GABA release

25
Q

What is the MOA of Phenobarbital?

A

-Prolongs opening of Chloride channel at GABA receptor

26
Q

What are the uses of Phenobarbital?

A
  • Partial seizures

- generalized tonic clonic seizures

27
Q

What are the drug interactions associated with phenobarbital?

A

Induction of CYP450s increases metabolism of phenytoin and carbamazepine

28
Q

What are the uses of Gabapentin?

A
  • Adjunct for partial and generalized tonic clonic seizures

- neuropathic pain

29
Q

What is the MOA of Gabapentin?

A

GABA analog

30
Q

What are the important pharmacokinetics of Gabapentin?

A
  • 1st order elimination

- excreted unchanged by the kidney

31
Q

What are the drug interactions with Gabapentin?

A

None really

32
Q

What is the MOA of Pregabalin?

A

-GABA analog, binds to alpha-2-delta subunit of voltage gated calcium channels inhibiting glutamate release

33
Q

What are the uses of Pregabalin?

A
  • generalized anxiety disorder

- neuropathic pain, fibro, post op pain

34
Q

What are the side effects of Pregabalin?

A
  • Peripheral edema, dizziness, fatigue, weight gain, xerostomia, blurred vision, GI disturbance
  • teratogenic
35
Q

What is the MOA of Tiagabine?

A

Inhibits reuptake of GABA

36
Q

What is the use of Tiagabine?

A

Adjunct treatment for partial seizures

37
Q

What are the common side effects with Tiagabine?

A
  • nervousness, difficulty concentrating, depression
  • dizziness and tremor are rare, but stop drug if it happens
  • Pregnancy category C
38
Q

What are the uses of Vigabatrin?

A
  • Refractory complex partial seizures

- infantile spasm (west’s syndrome)

39
Q

What is the MOA of Vigabatrin?

A

-Irreversibly inhibits GABA transaminase, decreases GABA metabolism

40
Q

What are the common side effects of Vigabatrin?

A
  • Visual field problems/retinal damage

- agitation, confusion

41
Q

What is the DOC for absence seizures?

A

Ethosuximide

42
Q

What is the MOA of ethosuximide?

A

-Inhibits lower threshold Ca channels , inhibits “pacemaker” for rhythmic cortical discharge

43
Q

What are the common side effects associated with Ethosuximide?

A
  • Hiccups
  • SJS (rare)
  • GI irritation, lethargy, fatigue, headache, dizziness
44
Q

What are the drug interactions with ethosuximide?

A

Metabolism is inhibited by valproic acid?

45
Q

What are the uses of Valproic acid?

A
  • absence and general tonic-clonic seizures
  • bipolar disorder
  • prophylaxis of migraine
46
Q

What is the MOA of Valproic acid?

A

Blocks Ca channels and Na channels, may enhance GABA activity

47
Q

What are the importance pharmacokinetics of Valproic acid?

A

-Inhibits its own metabolism at low doses

48
Q

What are the side effects of Valproic acid?

A
  • Hepatotoxicity (monitor liver function is recommended)
  • nausea, abdominal pain, heartburn, weight gain, sedation, alopecia
  • Pregnancy category D
49
Q

What are the uses of Clonazepam for seizures?

A

-absence seizures, myoclonic seizures, and infantile spasms (wests syndrome)

50
Q

What is the MOA of Clonazepam?

A

Stimulates GABA receptor and enhances GABAergic inhibition

51
Q

What are the side effects of Clonazepam?

A
  • sedating
  • tolerance to anti-seizure effect may develop
  • pregnancy category D
52
Q

What are the uses of Diazepam and Lorazepam for seizures?

A

Status epilepticus

53
Q

What is the MOA of Diazepam and Lorazepam?

A

Stimulates GABA channel

54
Q

What are the teratogenic effects of Anticonvulsants?

A
  • increased risk of congenital malformations

- valproic acid has increased risk of spina bifida

55
Q

What are the 4 main toxicities associated with anticonvulsants?

A
  • Teratogencity
  • withdrawal
  • Overdose
  • Suicidality
56
Q

What kind of anticonvulsants have a risk of SJS?

A

-drugs that block Na Channels (phenytoin, lamotrigine, Carbamezepine, and Valproate)