Anticonvulsants Flashcards

1
Q

what is a seizure

A

sudden intense electrical discharge in the thalamocortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is a convulsion

A

generalized tonic-clonic seizure that may or may not be associated with epilepsy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is tonic-clonic?

A

Tonus: increased mm tone

Clonus: alternating rapid contraction and relaxation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is status epilepticus

A

a series of seizures in rapid succession with no intervening periods of consciousness, lasting 30+ minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is epilepsy and what are its 3 characteristics

A

Recurrent, spontaneous impairment of brain function
- loss of consciousness
- abnormal motor function
- mental or sensory disturbances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the difference between a focal and generalized seizure

A

focal: usually unilateral involvement of the cerebrum, minor abnormalities

generalized: usually bilateral involvement of the cerebrum, loss of consciousness, tonic-clonic motor activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the goal of anticonvulsant therapy

A

reduce the frequency and severity of seizures, not abolish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the most common drugs used to PREVENT seizure

A
  • phenobarbital
  • KBr
  • levetiracetam
  • gabapentin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the most common drug used to STOP seizures

A

diazepam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

why cant we use diazepam for long-term control of seizures

A

tolerance develops within 1-2 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why is diazepam not a good treatment for seizures in cats

A

hepatic toxicity likely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why do we use so few anticonvulsant drugs in animals when so many exist in humans

A

1) metabolized very differently in dogs and cats (numerous daily doses)
2) different adverse effects
3) cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

T/F combination therapy for anticonvulsants is very common

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the #1 anticonvulsant in small animals

A

Phenobarbital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what type of drug is phenobarbital

A

barbiturate with anticonvulsant activity at low concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how does phenobarbital prevent seizures

A

facilitates GABA (hyperpolarizes cells)

17
Q

what is phenobarbital half life in:
- dogs
- cats

A

dogs: 20-140, ~48h
cats: <48h

in dogs, the half-life decreases with duration of therapy due to induction of p450 enzymes so you have to increase dose gradually throughout life

18
Q

what do you do if you have been treating a dog with phenobarbital for long enough that you are reading toxic doses

A

add an adjunct therapy or switch to KBr

19
Q

what are the advantages of phenobarbital as an anticonvulsant (4)

A

1) inexpensive
2) q12 administration
3) best outcomes of any monotherapy for dog/cat epilepsy
4) effective in many species

20
Q

what are the main disadvantages of phenobarbital as an anticonvulsant (4)

A
  • sedation (can last ~2w)
  • PU/PD, V, polyphagia (can persist)
  • induces cytochrome p450 in dogs
  • potential hepatotoxicity due to drug tolerance
21
Q

how do we get around the disadvantages of phenobarbital

A

monitor blood levels

22
Q

what is a rare possible side effect of KBr phenobarbital therapy (and all other anticonvulsants)

A

pancreatitis

23
Q

how should you transition between anticonvulsants

A

taper blood levels by ~10% every 3 weeks

24
Q

what is the most common anticonvulsant used in cats

A

phenobarbital

25
what anticonvulsant is contraindicated in cats and why
KBr: causes an asthma-like condition in cats which can be fatal
26
what is the MoA of KBr
hyperpolarizes membranes by flowing through Cl channels in neuron PM
27
what are the advantages of KBr
- effect can be as good as PB - no hepatic metabolism (no toxicity, no changes in dose required over time) - q24 administration - cheap
28
what are the man disadvantages of KBr
- sedation and lethargy - PU/PD/PP/V and V may persist - cannot use in cats due to pulmonary inflammation - long half-life means it takes months to titrate to effect - narrow therapeutic index
29
T/F KBr is not sold as a pharmaceutical
T -> prepared from industrial powder
30
what is an important dietary consideration for a patient on KBr
the body treats Cl- and Br- the same, so diets that increase Cl- will increase Br- excretion in the kidney
31
what is the MoA of levetiracetam
unknown
32
how is Levetiracetam given
12 daily as an adjunct, commonly with phenobarbital
33
how do we use gabapentin as an anticonvulsant
q12h treatment in combination with other anticonvulsants
34
what is the MoA of gabapentin
synthetic analogue of GABA
35
what are the dangers of using diazepam in cats
- idiosyncratic hepatic necrosis - hepatic toxicity
36
how can diazepam be administered - in clinic - at home
- in clinic: IV - at home: per rectum
37
when and how frequently would diazepam be given by an owner at home (or in hospital)
at first sign of seizure (prodromal sign); repeat at 20 and 40 min
38
what should you use if diazepam fails to stop a seizure
IV phenobarbital, then try general anesthetics (propofol, inhalant)
39
why don't we use the following drugs in animals: - primidone - phenytoin - clonazepam
Primidone: hepatic toxicity worse than PB Phenytoin: half-life in dogs too short to be useful Clonazepam: ineffective after 1-2 months