Anti-epileptics Flashcards

1
Q

Simple partial seizure?

A
• There is no loss of
consciousness.
• Often there is abnormal
activity of a single limb
or muscle group.
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2
Q

Complex partial seizure?

A

• There is loss of consciousness.
• Motor dysfunction may involve chewing
movements, diarrhea, urination.

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3
Q

Partial with secondarily generalized tonic-clonic seizure?

A

• The partial seizure evolves into a tonic clonic seizure with loss of consciousness.

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4
Q

Generalized tonic-clonic seizures?

A
  • No evidence of localized onset.
  • They may be convulsive or non-convulsive.
  • There is immediate loss of consciousness.
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5
Q

Absent seizures (generalized)?

A
  • Brief, abrupt and self-limiting loss of consciousness.
  • The patient stares and exhibits rapid eye-blinking.

EEG - 3 Hz spike-and-wave pattern emerges abruptly and ceases after a few seconds

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6
Q

Mechanisms of seizures?

A
  1. trigger seizures - GABAa antagonists or glutamate agonist

2. inhibit seizure - GABAa enhancement or glutamate receptor antagonists

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7
Q

General MOA of anti-epileptic drugs?

A
  1. blockage of VG ion channels - VG Na+ and T-type Ca2+

2. modulation of synaptic transmission

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8
Q

Drugs that block VG Na+ channels?

A
  1. phenytoin
  2. carbamazepine
  3. Lamotrigine
  4. Zonisamide
  5. Phenobarital, valproate, topiramate?

**blocking VG Na+ channels blocks AP and therefore glutamate release

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9
Q

Drugs that block T-type Ca2+ channels?

A

Absence seizures involve oscillatory neuronal activity b/t thalamus and cortex that uses T-type Ca2+ channels.

Ethosuximide and Valproate inhibit the Ty-type Ca2_ channels and are therefore effective against absence seizures.

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10
Q

Drugs that enhance GABAergic neurotransmission postsynaptically?

A

Direct action on GABAa receptors..

  1. benzodiazepines
  2. barbiturates
  3. Topiramate
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11
Q

Drugs that enhance GABAergic neurotransmission presynaptically?

A
  1. inhibit GABA reuptake - Tiagabine

2. inhibit GABA degradation (GABA aminotransferase) - Vigabatrin

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12
Q

Drugs that reduce glutamatergic neurotransmission postsynaptically?

A

Phenobarbital an Topiramate - block glutamate receptors

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13
Q

Drugs that reduce glutamatergic neurotransmission presynaptically?

A
  1. Gabapentin and pregabalin - decrease glutamate release by blocking VG Ca2+ channels
  2. Levetiracetam - binds synaptic vesicle glycoprotein 2A (SV2A) - may affect release of glutamate and GABA - very unclear as to what it does other than binding to protein in the vesicle membrane
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14
Q

Drugs used in partial and secondarily Generalized tonic-clonic seizures?

A
  • Carbamazepine -
  • Oxcarbazepine-
  • Levetiracetam
  • Zonisamide
  • Phenytoin -
  • Valproate -
  • Lamotrigine -
  • Topiramate -
  • Phenobarbital

All of the ones with (-) you can use for generalized tonic clonic seizures.

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15
Q

DOC of absence seizures?

A

Ethosuximide and Valproate

If on top of absence seizure there are tonic-clonic seizures - use Valproate NOT ethosuximide

If absence seizures are atypical (look like absence seizures, but lack of the 3Hz EEG pattern) - use Valproate over ethosuximide

**Lamotrigine is a newer drug that has recently become popular and may be effective

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16
Q

DOC of myoclonic seizures?

A

Valproate
2nd line - Topiramate
Adjuvant - Levetiracetam

17
Q

Tx of atonic seizures?

A

Valproate and Lamotrigine

18
Q

Tx of febrile convulsions?

A

If seizure lasts less than 15 minutes, tx is supportive. If seizure lasts more than 15 minutes, pharmacological tx is needed to prevent brain damage.

Tx - diazepam given IV or as a rectal solution

19
Q

Tx of status epilepticus?

A
  1. IV lorazepam
  2. if seizure continues - IV phenytoin or Fosphenytoin (soluble with better bioavailability)
  3. if seizure continues - IV phenobarbital
  4. if seizure continues - general anesthesia with IV midazolam, propofol or barbiturates
20
Q

Manage convulsive episode in non-epileptic pts?

A

Diazepam, Lorazepam, or phenobarbital

21
Q

Tx of breakthrough seizure?

A

Seizures experienced by epileptic pt who is already on antiepileptic therapy.

Tx - diazepam rectal gel supplied as a pre-filled syringe

22
Q

Which anti-epileptic drug induces cytochrome P450?

A

Carbamazepine
Phenobarbital
Phenytoin
Oxcarbazepine (similar to carbamazepine) - weak inducer

23
Q

AE Valproate?

A
  • Hepatotoxicity.
  • Inhibits cytochrome P450.
  • Inhibits metabolism of several drugs.
  • Inhibits its own metabolism.
24
Q

AE phenytoin?

A
  • Diplopia, ataxia.
  • Gingival hyperplasia****
  • Coarsening of facial features in children.
  • Hirsutism.
  • Rash. Stevens-Johnson Syndrome.
  • Zero order kinetics of elimination.
25
Q

Which anti-epiletpics have high risk of rash and Stevens-Johnson syndrome?

A
  1. phenytoin
  2. lamotrigine (black box warning that first sign of rash should lead to discontinuation)*
  3. carbamazepine
  4. phenobarbital
26
Q

AE phenobarbital?

A
  • Sedation, drowsiness.
  • Rash. Stevens-Johnson syndrome.
  • Tolerance, dependence.
  • Cognitive impairment, hyperactivity.
  • P450 inducer.

**Primidone is metabolized to phenobarbital so it has similar AE effects

27
Q

Vigabatrin AE?

A

Irreversible visual field loss

28
Q

AE Felbamate?

A
  • Aplastic anemia
  • Hepatotoxicity
  • Only use for For refractory epilepsy**
29
Q

Most dangerous effect of large anti-epileptic medication overdose?

A

Respiratory depression - esp with phenobarbital?

30
Q

Which anti-epileptics should be used during pregnancy?

A

Increasd risk of congenital malformationsin infantsorn of women taking anti-seizure drugs.

Valproate - has the highest rate of fetal malformations compared to other anti-epileptic drugs

**use folic acid to reduce incidence of amlformations

31
Q

Newborn hemorrhagic disease?

A

Enzyme-inducing anti-epiletpic drugs may increased degradation of vitamin K in the fetus leading to bleeding in the newborn infant. The mother should take vitamin K supplementation in the final months of pregnancy for the newborn.

32
Q

What is the effect of the ketogenic diet on epilepsy management?

A
  • high fat content and extremely low carb content produces ketosis
  • ketosis suppresses the seizures
  • exact MOA is unclear
33
Q

What is the effect of vagus nerve stimulation on epilepsy management?

A

Intermittent electrical stimulation of the left vagus nerve with an implanted pacemaker-like device that pt can activate when a seizure is coming and it stops the seizures.