Lecture 15: Anticonvulsants Flashcards

1
Q

Seizures are ____firing of brain neurons

A

Disordered, synchronous, rhythmic firing

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2
Q

Seizures may result from too much___ or too little ____

A

Glutamate, gaba

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3
Q

What is the drug of choice for status epilepticus

A

Diazepam (or other benzos)

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4
Q

What is the MOA for benzos

A

Bind GABAa receptor open Cl- channels resulting in hyperpolarization

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5
Q

How does phenobarbital work

A

Bind GABAa receptors, open Cl- channels and hyperpolarize

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6
Q

What is phenobarbital used for

A

Maintenance therapy of seizure disorders in dogs and cats

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7
Q

Chronic use of phenobarbital can cause what

A

Increase P450- increase drug interactions

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8
Q

What are some side effects of phenobarbital

A

PU/PD, polyphasia, sedation

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9
Q

Phenobarbital can increase ___ and ___ enzymes

A

TSH and liver enzymes

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10
Q

What are some adverse effects of phenobarbital

A

Liver toxicity, superficial necrolytic dermatitis

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11
Q

How does levetiracetam work

A

Binds synaptic vesicular protein (SV2A) and inhibits NT release

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12
Q

Levetiracetam seems to decrease ___and decrease ___

A

Likelihood of seizures and brain damage caused by seizures

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13
Q

What is levetiracetam used for

A

Monotherapy or add on with phenobarbital to tx seizures

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14
Q

What is the preferred tx for refractory epilepsy in dogs

A

Levetiracetam

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15
Q

What are some side effects of levetiracetam

A

Sedation, vomiting, anorexia

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16
Q

What is MOA of KBr

A

Br- enter via Cl- channels causing hyperpolarization

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17
Q

What is KBr used for

A

Refractory seizures in dogs as monotherapy or with phenobarbital

18
Q

What species is KBr not recommended in and why

A

Cats- cause asthma d/t airway inflammation

19
Q

What anticonvulsant has greater excretion with high chloride and the owner should tell you of any dietary changes

A

KBr

20
Q

What are some side effects of KBr

A

PU/PD, polyphagia, lethargy, pancreatitis

21
Q

What are some signs of toxicity with KBr

A

Vomiting, constipation, ataxia, sedation, joint stiffness in rear limbs

22
Q

What is the MOA for gabapentin

A

Inhibits N type Ca2+ channels which are unregulated in epileptic or neuropathic pain and decreases excitatory NT release

23
Q

What is gabapentin used for

A

Adjunct tx for refractory seizures and tx of pain

24
Q

What is the MOA for felbamate

A

Multiple mechanisms- Na2+, Ca2+ and GABA

25
Q

What is felbamate used for

A

Add on for partial complex or generalized seizures that have not responded to other drugs

26
Q

Felbamate may increase ___levels

A

Phenobarbital

27
Q

Felbamate can cause ___ damage in dogs

A

Liver

28
Q

What is zonisamide used for

A

Add on for refractory epilepsy and occasionally used as monotherapy in dogs

29
Q

What are some side effects of zonisamide

A

Sedation, anorexia, vomiting, ataxia in cats

30
Q

Avoid zonisamide in what patients

A

Pregnant- teratogenic

31
Q

What is the mechanism of action of valorous acid

A

Blocks high-frequency repetitive firing on neurons, probably blocks Na+ channels and enhance GABA activity

32
Q

When is valproic acid used

A

Rarely used, use if other drugs not effective

33
Q

Valproic causes ___ especially with phenobarbital by increasing phenobarbital levels

A

Sedation

34
Q

You don’t want to give valproic acid to ___patients

A

Pregnant- teratogenic

35
Q

___toxicity can be severe with valproic acid

A

Hepatotoxicty

36
Q

What is the MOA of phenytoin

A

Blocks high frequency repetitive firing or neurons, prolongs inactivation of Na+ channels

37
Q

___is not recommended for maintenance therapy due to problems with half-life and toxicity

A

Phenytoin

38
Q

What are the problems with phenytoin half life and toxicity

A

Half life too short in dogs-ineffective
Half life too long in cats- toxic

39
Q

Chronic use of phenytoin causes ___ and ___

A

Gingival hyperplasia and hepatotoxicity

40
Q

___ is used primarily as a last resort for status epilepticus (or antiarrhythmic) and as an add in to produce sedation for euthanasia

A

Phenytoin

41
Q

What is the order of drugs to tx seizures with normal liver function

A
  1. Initial therapy- Phenobarbital
  2. Add levetiracetam, KBr, zonisamide, gabapentin, prenatal in
  3. Felbamate
42
Q

What is the order of drugs to tx seizures with abnormal liver function

A
  1. KBr +/- Levetiracetam
  2. Levetiracetam