Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Introduction to Pharmacology > Anticonvulsants > Flashcards

Anticonvulsants Flashcards

1
Q

What is a seizure?

A

an abnormal, disorderly discharging of the brain’s nerve cells, resulting in a temporary disturbance of motor, sensory, and mental function
(epilepsy)

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

What are 10 symptoms of seizures in dogs?

A
  1. entire body convulsions
  2. facial tremors
  3. excessive drooling
  4. defecating
  5. unusual barking
  6. running in circles
  7. twitching
  8. biting
  9. urinary incontinence
  10. going unconsious
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do anticonvulsant drugs work? What is the goal of therapy?

A

block seizure initiation and propagation by blocking either abnormal events in a single neuron or the synchronization of related neurons

reduction in the firing frequency of neurons

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

Why are there not many human anticonvulsants approved for use in dogs and cats?

A

too rapidly metabolized in dogs to be effecive, even in high dosages

cats metabolize these drugs more slowly and poorly than dogs

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

What is the mechanism of action of anticonvulsants? In what 3 ways do they do this?

A

stabilize neuronal membranes evoking hyperpolarization

  1. activate GABA-gated Cl- channels
  2. bind to GABA(a) receptor and facilitate its action (agonist)
  3. inactivating Na+ and Ca+ conductance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the main therapeutic use of anticonvulsants? What are 3 common adverse effects?

A

reduction of incidence, severity, and duration of seizures

  1. rapid cessation effect of administration (rapidly cleared by liver)
  2. liver and serum enzyme induction (more enzymes activated at once)
  3. hepatotoxicity in dogs due to the higher dose needed for possible effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 4 most common drugs used as anticonvulsants?

A
  1. barbiturates
  2. benzodiazepines
  3. hydantoins
  4. valproic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What 4 unconventional drugs are used as anticonvulsants?

A
  1. Gabapentin
  2. Levetiracetam
  3. Felbamate
  4. Zonisamide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is GABA? Where is it produced? What is needed for its synthesis?

A

(gamma aminobutyric acid)
major inhibitory NT in the CNS —> natural “valium-like” NT

mostly in the brain from glutamic acid/glutamate

vitamin B6

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

What does GABA play an important role in?

A

inhibiting or reducing the activity of neurons
- behavior
- cognition
- body response to stress
- fear and anxiety

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

How do GABA(a) receptors work?

A

GABA-gated chloride channels cause chloride (Cl-) ions to flow into their neuron when activated, causing is hyperpolarization
- inhibition!

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

How do barbiturates work? What 3 are most commonly used?

A

activates GABA-gated Cl- channels

  1. Phenobarbital (oxybarbiturate)
  2. Pentobarbital (oxybarbiturate)
  3. Primidone (analog of phenobarbital)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is phenobarbital a unique barbituate? What is it usually used for?

A

produces an anticonvulsant effect at lower doses than those necessary to cause pronounced CNS depression (sedation)

long-term control of seizures
- NOT useful for terminating an ongoing seizure because the time span from administration until offset of effect is too long (given PO)

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

What are 5 adverse effects of Phenobarbital?

A
  1. sedation
  2. polydipsia
  3. polyuria
  4. polyphagia
  5. dogs develop a tolerance to sedative effects after 1-2 weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What kind of barbiturate is Primidone? What happens when it reaches the liver?

A

it is a deoxybarbiturate

rapidly metabolized into phenobarbital (active form)

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

Why is Primidone not used in cats?

A

metabolism into phenobarbital is too slow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens with prolonged use of Primidone in dogs?

A

decreased serum albumin, elevated serum concentrations of liver enzymes, liver damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In what situation is Pentobarbital used?

A

status epilepticus —> seizure lasting longer than 5 mins, or having more than one seizure within a 5 min period without returning to a normal level of consciousness between episodes
- terminates seizures at a dose that produces anesthesia, rapid onset IV with short duration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are 3 common adverse effects of Pentobarbital?

A
  1. CNS depressant
  2. excitement during recovery from anesthesia
  3. irritating when administered perivascularly
20
Q

How do Benzodiazepines work as anticonvulsants? In what species are they used? What 4 are most commonly used?

A

facilitate inhibitory action of GABA by binding GABA(a) receptors and evoking hyperpolarization of the neurons

all domestic species

  1. Diazepam
  2. Midazepam (Zolam)
  3. Clonazepam
  4. Lorazepam
21
Q

Can benzodiazepines be used to treat status epilepticus? How are they used in dogs and cats?

A

yes

DOGS: limited use as a maintenance anticonvulsant due to a development of tolerance because of rapid drug metabolism
CATS: can be used as a maintenance anticonvulsant

22
Q

How does therapeutic uses of Diazepam as an anticonvulsant compare in dogs and cats?

A

DOGS: administered IV, drug of choic for the control of status epilepticus and cluster seizures

CATS: administered orally for seizure control

23
Q

What are 2 adverse effects of Diazepam as an anticonvulsant?

A
  1. changes in behavior (irritability, depression, aberrant demeanor)
  2. cats can develop acute fatal hepatic necrosis
24
Q

How does Midazolam compare to Diazepam? In what 4 situations is it used?

A

more potent

  1. status epilepticus
  2. muscle relaxant
  3. tranquilizer
  4. appetite stimulant
25
Q

What are 4 common adverse effects of Midazolam?

A
  1. mild respiratory depression
  2. vomiting
  3. restless behavior, agitation
  4. local irritation
26
Q

Why does Clonazepam have a limited value as a maintenance anticonvulsant? What are 2 common adverse effects?

A

rapid development of drug tolerance

  1. drug resistance
  2. GI disturbance, including vomiting, hypersalivation, and diarrhea/constipation
27
Q

When is Lorazepam most commonly used as an anticonvulsant? What is a major benefit to this drug over other benzodiazepines?

A

short term at-home treatment for dogs having cluster seizures
maintenance anticonvulsant in cats

may be used safely in patients with compromised liver function and geriatric dogs because it does not produce metabolites

28
Q

What are 2 common adverse effects of Lorazepam?

A
  1. increased appetite
  2. anxiety during early therapy
29
Q

How do hydantoins work? What one is usually used as an anticonvulsant?

A

target sodium (Na+) channels, blocking channels from recovering from the inactive state leading to inhibition of neuron firing

Phenytoin —> derivative

30
Q

What is Phenytoin use commonly impractical in dogs? What is it usually used for?

A

short half-life

lidocain-like effects —> treatment of digitalis-induced ventricular arrhythmias in dogs

31
Q

What is valproic acid? How does it work?

A

derivative of carboxylic acid (structurally unrelated to other anticonvulsants)

stabilizes membranes by blocking Na+ and Ca++ channels and openining GABA-gated Cl- channels

32
Q

How does usefulness of valproic acid as an anticonvulsant compare in dogs and cats?

A

DOG - short half-life makes long-term use impractical, but it can still be useful in controlling seizures

CAT - clinical usefulness has not been evaluated

33
Q

What are 7 possible adverse effects of valproic acid?

A
  1. GI toxicity: vomiting, anorexia, diarrhea
  2. hepatotoxicity: liver failure in dogs
  3. CNS effects: sedation, ataxia, behavioral changes
  4. dermatologic effects: alopecia, rash
  5. hematologic effects: thrombocytopenia, leukopenia, anemia
  6. pancreatitis
  7. edema
34
Q

How does potassium bromide work as an anticonvulsant? What is its half-life like when administered orally?

A

Br- enters neurons via Cl- channels causing hyperpolarization of the neuronal membrane

LONG - neither metabolized nor bound to plasma proteins (can take up to 6 months to achieve stable plasma concentrations and elimination)

35
Q

Is potassium bromide used as an anticonvulsant in cats?

A

no

36
Q

What are 5 adverse effects of potassium bromide?

A
  1. transient sedation at the beginning of therapy
  2. GI toxicity: nausea, vomiting, anorexia, constipation
  3. PD, PU, polyphagia, lethargy, irritability, aimless walking
  4. pancreatitis
  5. severe asthma in cats
37
Q

What is Gabapentin? How is it usually given? What unique treatment is it also used for?

A

synthetic GABA analog that can cross the BBB to exert its anticonvulsant effect (MOA unknown)

PO, used as adjunctive therapy for refractory of complex partial seizures

chronic pain in dogs and cats

38
Q

What are 3 adverse effects of Gabapentin? What can abrupt discontinuation cause?

A
  1. sedation
  2. ataxia
  3. mild polyphagia`

seizures

39
Q

How does Levetiracetam work? What therapeutic use does it have?

A

inhibition of firing and propagation of seizure activity through binding synaptic protein 2A

administered orally as adjunctive therapy for refractory canine epilepsy (well tolerated in dogs and cats)

40
Q

What are 2 adverse effects of Levetiracetam? What can abrupt discontinuation cause?

A
  1. GI disturbances: vomiting, anorexia
  2. changes in behavior, drowsiness

seizures

41
Q

How does Felbamate work? How is it used?

A

blockade of neural excitation and potentiation of GABA mediated inhibition through inhibition of voltage-dependent Na+ and Ca++ channels

PO, adjunctive therapy for refractory canine epilepsy

42
Q

When is Felbamate used as a sole anticonvulsant? When is it particularly useful?

A

for patients with local and generalized seizures

brain tumor or cerebral infarcts, due to no sedation effect

43
Q

What is the most common adverse effect of Felbamate? What are 2 rare adverse effects?

A

liver dysfunction in dogs

  1. reversible bone marrow depression (thrombocytopenia/leukopenia) in dogs
  2. generalized tremor and/or keratoconjunctivitis sicca in dogs
44
Q

How does Zonisamide work? When is it used as adjunctive therapy? Sole anticonvulsant?

A

induction of neural hyperpolarization through inhibition of voltage-dependent Na+ and Ca++ channels

refractory canine epilepsy (less often in cats)
patients with local and generalized seizures

45
Q

When is Zonisamide particularly useful? What is its major benefit? What are rare adverse effects?

A

brain tumors or cerebral infarct (no sedation)

high safety margin in dogs and cats

sedation, ataxia, anorexia

46
Q

What are 2 major drawbacks to using Zonisamide as an anticonvulsant?

A
  1. cost
  2. not enough data for cats

Introduction to Pharmacology (39 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions