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Claude Flashcards > Epilepsy > Flashcards

Epilepsy Flashcards

1
Q

What are the three main mechanisms of action for antiepileptic drugs?

A
  1. Blocking voltage-gated channels (Na+ or Ca2+).
  2. Enhancing inhibitory GABA-ergic impulses.
  3. Interfering with excitatory glutamate transmission.
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2
Q

Which voltage-gated channels do some antiepileptic drugs block?

A

Voltage-gated Na+ or Ca2+ channels.

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3
Q

How do some antiepileptic drugs affect GABA-ergic impulses?

A

They enhance inhibitory γ-aminobutyric acid (GABA)-ergic impulses.

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4
Q

How do some antiepileptic drugs interact with glutamate transmission?

A

By interfering with excitatory glutamate transmission.

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5
Q

What is the mechanism of action of benzodiazepines as antiepileptic drugs?

A

Benzodiazepines bind to GABA inhibitory receptors, reducing neuronal firing rate.

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6
Q

Which two benzodiazepines are used for treating epilepsy?

A
  • Diazepam.
  • Lorazepam.
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7
Q

What types of seizures do benzodiazepines treat?

A
  • Myoclonic seizures.
  • Partial seizures.
  • Generalized tonic-clonic seizures.
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8
Q

How is diazepam is used for emergency seizure treatment?

A

Rectal administration to avoid prolonged generalized tonic-clonic seizures.

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9
Q

Which benzodiazepine is administered rectally in seizure emergencies for generalized tonic-clonic?

A

Diazepam.

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10
Q

What is the first-line treatment for status epilepticus (FDA guideline)?

A

Benzodiazepines.

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11
Q

What is the mechanism of action of carbamazepine?

A

Blocks sodium channels, inhibiting repetitive action potentials in epileptic focus and preventing their spread.

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12
Q

What types of seizures is carbamazepine effective for?

A

Partial seizures and secondarily generalized tonic-clonic seizures.

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13
Q

What non-epileptic conditions can carbamazepine treat?

A

Trigeminal neuralgia and bipolar disorder.

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14
Q

What is a key metabolic characteristic of carbamazepine?

A

It induces its own drug metabolism.

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15
Q

What is a dangerous side effect of the epoxide metabolite of carbamazepine?

A

Blood dyscrasias.

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16
Q

What enzyme families does carbamazepine induce?

A

CYP450s and UGT enzymes.

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17
Q

Why should carbamazepine not be prescribed for absence seizures?

A

It may cause an increase in seizures due to GABA receptor activation in the ventrobasal complex.

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18
Q

What are two ophthalmic side effects of carbamazepine?

A

Diplopia (double vision) and blurred vision.

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19
Q

What electrolyte imbalance can carbamazepine cause, and why?

A

Hyponatremia (due to ADH secretion).

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20
Q

What is the active form of oxcarbazepine?

A

Monohydroxy (MHD) metabolite.

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21
Q

How does oxcarbazepine exert its anticonvulsant effect?

A

Blocks sodium channels, preventing spread of abnormal discharge.

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22
Q

What type of seizures is oxcarbazepine used to treat?

A

Partial onset seizures.

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23
Q

How does oxcarbazepine compare to carbamazepine in enzyme induction?

A

Less potent inducer of CYP3A4 and UGT.

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24
Q

What is an advantage of oxcarbazepine’s lower enzyme induction?

A

Low drug-drug interactions.

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25
Q

List four common side effects of oxcarbazepine.

A

Nausea, vomiting, headache, and visual disturbances.

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26
Q

What is the primary mechanism of action of phenytoin and fosphenytoin?

A

Blocks voltage-gated sodium channels by selectively binding to the channel in the inactive state and slowing its rate of recovery.

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27
Q

What secondary effects does phenytoin have at very high concentrations?

A

a) Blocks voltage-dependent calcium channels.
b) Interferes with the release of monoaminergic neurotransmitters.

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28
Q

What types of seizures is phenytoin effective in treating?

A
  • Partial seizures.
  • Generalized tonic-clonic seizures.
  • Status epilepticus.
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29
Q

Besides epilepsy, what other condition is phenytoin used to treat?

A

Trigeminal neuralgia.

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30
Q

Why should phenytoin not be used for absence seizures?

A

It has the potential to exacerbate absence epilepsy.

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31
Q

What enzyme system does phenytoin induce?

A

Drug-metabolized enzyme system.

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32
Q

How does phenytoin’s enzyme metabolism change at low serum concentrations?

A

It becomes saturable.

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33
Q

What can result from small increases in phenytoin’s daily dose?

A

Large increases in plasma concentration, potentially leading to drug-induced toxicity.

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34
Q

What CNS-related side effect can phenytoin cause?

A

Depression of the CNS, causing nystagmus (rapid involuntary eye movements) and ataxia.

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35
Q

What dental side effect is associated with phenytoin use?

A

Gingival hyperplasia.

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36
Q

What long-term neurological side effect may phenytoin cause?

A

Development of peripheral neuropathies.

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37
Q

What bone-related side effect is associated with long-term phenytoin use?

A

Osteoporosis.

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38
Q

What type of anemia is phenytoin associated with?

A

Risk of megaloblastic anemia.

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39
Q

What is fosphenytoin in relation to phenytoin?

A

Fosphenytoin is a prodrug that is rapidly converted to phenytoin in the blood.

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40
Q

Which antiepileptic drug is an analog of GABA?

A

Gabapentin.

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41
Q

What is the mechanism of action of gabapentin?

A

Unknown. It doesn’t bind to & activate GABA receptors.

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42
Q

What is the primary use of Gabapentin as an antiepileptic drug?

A

Adjunct therapy for partial seizures.

43
Q

What is a non-epileptic use of Gabapentin?

A

Treatment of postherpetic neuralgia (nerve pain caused by varicella zoster virus).

44
Q

What characteristic of Gabapentin’s pharmacokinetics is notable?

A

Nonlinear pharmacokinetics due to saturable transporter uptake in the gut.

45
Q

Why is Gabapentin considered to have low drug-drug interaction potential?

A

It doesn’t bind to plasma proteins and is excreted unchanged through the kidneys.

46
Q

Why is Gabapentin often preferred for older patients?

A

It is well tolerated due to its mild side effects.

47
Q

What is the mechanism of action (MOA) of Tiagabine?

A

Blocks GABA uptake into presynaptic neurons.

48
Q

How does Tiagabine’s MOA enhance inhibitory activity?

A

By permitting more GABA to be available for receptor binding.

49
Q

For which type of epilepsy is Tiagabine effective?

A

Partial onset epilepsy.

50
Q

Is Tiagabine approved for use in absence seizures?

A

No, it is not used for absence seizures.

51
Q

What are the main mechanisms of action for lamotrigine?

A

Blocks sodium channels and high voltage-dependent calcium channels.

52
Q

What types of seizures is lamotrigine used to treat?

A
  • Partial seizures.
  • Generalized seizures.
  • Typical absence seizures.
53
Q

Besides epilepsy, what other condition is lamotrigine used to treat?

A

Bipolar disorder.

54
Q

How do enzyme-inducing drugs affect lamotrigine’s half-life?

A

They reduce it (e.g. carbamazepine).

55
Q

How do enzyme-inhibitor drugs affect lamotrigine’s half-life?

A

They increase it (e.g. valproate).

56
Q

What serious side effect can rapid titration of lamotrigine cause?

A

A rash, which may progress to a serious, life-threatening reaction in some patients.

57
Q

Why is lamotrigine well-tolerated by the elderly population?

A

Due to minor side effects.

58
Q

What is the proposed mechanism of action for levetiracetam?

A

Action is unknown, but most probably on synaptic vesicle protein SV2A.

59
Q

What types of seizures is levetiracetam used to treat?

A
  • Partial onset seizures.
  • Myoclonic seizures.
  • Primary generalized tonic-clonic seizures in adults and children.
60
Q

How does levetiracetam interact with drug metabolism systems?

A

It does not interact with CYP or UGT metabolism systems, leading to low drug-drug interactions.

61
Q

What is the primary mechanism of action for phenobarbital?

A

Enhancing the inhibitory effects of GABA-mediated neurons.

62
Q

What is the main clinical use of phenobarbital in epilepsy treatment?

A

Used primarily in the treatment of status epilepticus.

63
Q

Why is phenobarbital considered only for chronic therapy in refractory patients?

A

Because of its high side effects (sedation, enzyme induction, and osteoporosis).

64
Q

What is the broad spectrum of action for felbamate?

A

Anticonvulsant action.

65
Q

What are the proposed mechanisms of action for felbamate? (List 4)

A

1) Blocking voltage-dependent sodium channels.
2) Competing with the glycine binding site on NMDA glutamate receptor.
3) Blocking calcium channels.
4) Potentiating the action of GABA.

66
Q

Why does felbamate have high drug-drug interactions?

A

It inhibits drugs metabolized by CYP2C19 and ß-oxidation, and induces drugs metabolized by CYP3A4.

67
Q

Why is felbamate used only in refractory epilepsies?

A

Due to the risk of aplastic anemia and heart failure.

68
Q

What side effect do carbamazepine and phenytoin share?

A
  • Decrease bone proliferation.
  • Decrease vitamin D.
69
Q

What is divalproex sodium?

A

A combination of sodium valproate and valproic acid that converts to valproate in the gastrointestinal tract.

70
Q

What is the purpose of using divalproex sodium instead of valproic acid alone?

A

To improve the gastrointestinal (GIT) tolerance of valproic acid.

71
Q

What are the three main mechanisms of action for valproic acid and divalproex?

A

1) Sodium channel blockade.
2) Blockade of GABA transaminase.
3) Blockade action at t-type calcium channels.

72
Q

What types of epilepsies are valproic acid and divalproex effective in treating?

A

Partial and primary generalized epilepsies.

73
Q

Why does valproic acid have a high potential for drug-drug interactions?

A

It inhibits metabolism of CYP2C9, UGT, and epoxide hydrolase systems.

74
Q

What is a rare but serious side effect of valproic acid?

A

Hepatic toxicity.

75
Q

Why is valproic acid contraindicated in pregnancy?

A

It is teratogenic, causing neural tube defects in the fetus.

76
Q

What are the five mechanisms of action for topiramate?

A

1) Blocks voltage-dependent sodium channels.
2) Increases chloride channel opening via GABA-A receptor.
3) Inhibits high-voltage calcium currents (L type), 4) Carbonic anhydrase inhibition, 5) May act at glutamate (NMDA) sites.

77
Q

Besides epilepsy, what other condition is topiramate used to treat?

A

Migraine.

78
Q

How does topiramate affect CYP2C19?

A

CYP2C19.

79
Q

Which drugs induce topirmate?

A

It is sensitive of induction by phenytoin and carbamazepine.

80
Q

How does topiramate affect oral contraceptives containing ethinyl estradiol?

A

It reduces ethinyl estradiol levels, potentially decreasing contraceptive efficacy.

81
Q

What are five common adverse effects of topiramate?

A

1) Somnolence.
2) Weight loss.
3) Paresthesias.
4) Renal stones.
5) Glaucoma.

82
Q

What is the mechanism behind topiramate-induced weight loss?

A

It causes anorexia.

83
Q

What serious adverse effect can topiramate cause due to metabolic acidosis?

A

Renal stones.

84
Q

What rare but potentially dangerous side effect can topiramate cause due to decreased sweating?

A

Hyperthermia (due to oligohidrosis).

85
Q

What is the broad mechanism of action for Zonisamide?

A

Blockade of both voltage-gated sodium channels and t-type calcium currents.

86
Q

What specific enzyme activity does Zonisamide affect?

A

Limited amount of carbonic anhydrase activity.

87
Q

What type of epilepsy is Zonisamide used to treat?

A

Partial epilepsy.

88
Q

What CNS-related side effect can Zonisamide cause?

A

CNS toxicity.

89
Q

How does Zonisamide affect body temperature?

A

It can cause increased temperature.

90
Q

What renal side effect is associated with Zonisamide?

A

Kidney stones (due to carbonic anhydrase inhibition leading to metabolic acidosis).

91
Q

What fluid balance disorder can Zonisamide cause?

A

Oligohidrosis.

92
Q

What is the primary mechanism of action for Ethosuximide?

A

Inhibits t-type calcium channels, reducing propagation of abnormal electrical activity in the brain

93
Q

For which specific type of seizures is Ethosuximide primarily used?

A

Only primary generalized absence seizures (first line treatment).

94
Q

Where are absence seizures triggered, and what causes them?

A

In the thalamus, when T-type calcium channels are activated, resulting in sustained-burst firing of neurons.

95
Q

Why is the use of Ethosuximide limited?

A

Because of its very narrow spectrum of activity

96
Q

What does vagal nerve stimulation for epilepsy require?

A

Surgical implant of a small pulse generator with a battery and a lead wire for stimulus.

97
Q

How does electrical vagus stimulation affect seizure patients?

A

It prevents abnormal electrical activity.

98
Q

When do patients activate the vagal nerve stimulator?

A

When they anticipate a seizure.

99
Q

For which type of seizures is vagal nerve stimulation effective?

A

Partial onset seizures.

100
Q

How does vagal nerve stimulation impact drug therapy for epilepsy?

A

It enables reduction of drug therapy.

101
Q

What type of epilepsy patients is vagal nerve stimulation used for?

A

Refractory patients.

102
Q

What should women with epilepsy take prior to conception?

A

High doses of folic acid.

103
Q

Which antiepileptic drugs should be avoided during pregnancy?

A

Divalproex and barbiturates.

104
Q

How should maintenance medication be adjusted when seizures are controlled during pregnancy?

A

Reduced to the lowest dose that provides control.

Claude Flashcards (6 decks)

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