Antiseizure, muscle relaxant Flashcards

1
Q

What are the different types of seizures?

A
Partial (simple, complex)
Generalized
-Tonic-clonic (grand mal)
-Absence (petit mal) = children
-Myoclonic
-Status epilepticus
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2
Q

What are the basic mechanisms of action for antiseizure agents? (3)

A
  1. affect abnormal membrane function (channels that lead to excessive depolarization)
  2. correct decreased inhibition (increase GABA function)
  3. reduce excitation (block glutamate receptors)
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3
Q

Phenytoin

target channel, mechanism, clinical uses

A
  • sodium channels
  • refractory period is increased => inhibits repetitive action potentials
  • generalized tonic-clonic seizure or partial seizures
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4
Q

How is pharmacokinetics of phenytoin affect drug interaction?

A

it is highly protein bound

-may interact with drugs that are protein bound

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5
Q

How is clearance affected as phenytoin dose is increased?

A

-dose-dependent => first-order to zero-order as dose is increased
(often while in therapeutic range)

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6
Q

Toxicity of phenytoin (5)

A
  • CNS - dose-dependent (nausea, anorexia, apathy, sedation, ataxia, nystagmus, diplopia)
  • BELOW not dose dependent*
  • gingival hyperplasia
  • hirsutism
  • teratogenicity (cleft palate)
  • rash
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7
Q

What is another antiseizure drug that is similar to phenytoin that causes rare blood dyscrasias and spinal bifida?

A

Carbamazepine

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8
Q

How is Oxcarbamazepine different from carbamazepine?

A

less CNS side effects

less enzyme induction

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9
Q

Mechanisms of action for phenobarbital (2)

A

GABA receptor - chloride ion channel

-selectively suppress abnormal neurons by suppressing firing from the foci and inhibiting spread

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10
Q

Why is phenobarbital primarily used in infants despite its effectiveness against tonic-clonic seizures?

A

because of its sedative effects

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11
Q

Which drug is used to treat absence seizure?

A

Ethosuximide

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12
Q

What is the mechanism of action for ethosuximide?

A

reduces low-threshold (T-type) Calcium current in thalamic neurons

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13
Q

How safe is ethosuximide?

A

among the safest of antiseizure drugs

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14
Q

Which antiseizure drug is used for absence seizures as well as tonic-clonic & myoclonic seizures?

A

Valproic acid

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15
Q

Describe the mechanisms of action for valproic acid (3)

A
  • blocks repetitive neuronal firing
  • reduce T-type Ca++ current
  • increase GABA concentration
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16
Q

What are some toxicities related to valproic acid? (3)

A
  • idiosyncratic hepatotoxicity (also interferes with metabolism of phenobarbital, phenytoin, and carbamazepine)
  • teratogenicity (spinal bifida)
  • weight gain, hair loss
17
Q

Which drug of benzodiazepines is used as a long acting drug effective against absence seizures and some types of myoclonic seizures?

A

Clonazepam

18
Q

Which two of benzodiazepines is used I.V. in status epilepticus?

A

diazepam, lorazepam

19
Q

Which antiseizure drug is an antagonist for NMDA receptor (glutamate receptor)?

A

Felbamate

20
Q

Why is use of felbamate limited to partial seizures that are refractory to other drugs?

A

occurrence of aplastic anemia and hepatic failure (otherwise very effective)

21
Q

Main use for pregabalin other than for partial seizures

A

management of neuropathic pain (diabetic, postherpetic, fibromyalgia)
-drug abuse limits use

22
Q

What is a serious toxicity for lamotrigine?

A

Stevens-Johnson syndrome
=> malaise, fever
erythematous/purpuric macules
epidermal necrosis and sloughing

23
Q

Main function of topiramate

A

blocks spread of seizure rather than raising seizure threshold
(also cause weight loss)

24
Q

What is the mechanism of tiagabine?

A

inhibits GABA transporter

=> increases GABA in synapse

25
Q

What is the mechanism of zonisamide?

A

inhibits T-type Ca++ channel and Na+ channel

26
Q

What is the mechanism of vigabatrin?

A

irreversibly inhibits GABA transaminase

=> increase in GABA

27
Q

Why is vigabatrin subject to restricted prescribing program?

A

permanent effects on vision

28
Q

What is the biggest problem in using diazepam as a muscle relaxant?

A

sedation

29
Q

What receptor does Baclofen target and how does it decrease the release of excitatory transmitters such as glutamate?

A

act on GABA-B receptors

  • > hyperpolarization
  • > presynaptic inhibition
30
Q

Why is Baclofen better than diazepam?

A

much less sedation

31
Q

Target for tizanidine?

A

alpha 2 receptor agonist