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Intro to Pharmacology > Week 6 - Anticonvulsants > Flashcards

Week 6 - Anticonvulsants Flashcards

1
Q

A seizure is defined as an abnormal, disorderly discharging of the brain’s ____ cells, resulting
in a _______ disturbance of ____, _____, and _____ function.

A

nerve, temporary, motor, sensory, mental

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2
Q

What are the symptoms of seizures in dogs?

A
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3
Q

What are the characteristics of epilepsy in dogs?

A
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4
Q

Anticonvulsants are used to block seizure ______ and ______ by blocking either
abnormal events in a ____ neuron or the synchronization of ______ neurons

A

initiation, propagation, single, related

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5
Q

What is the goal of anticonvulsant therapy?

A

Reduction in the firing frequency of neurons.

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6
Q

True or False: Only a few of the anticonvulsant drugs available for human use have been
approved for clinical use in dogs and cats.

A

True

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7
Q

Some of the drugs are too ______ ______ in dogs to be effective, even in high dosages.

A

rapidly metabolized

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8
Q

Cats metabolize drugs more ______ and _____ than dogs.

A

slowly, poorly

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9
Q

What is the mechanism of action (MOA) of anticonvulsant drugs?

A

MOA: Stabilization of the neuronal membranes evoking hyperpolarization
* They activate GABA-gated Cl- channels
* They bind to GABAA receptor and facilitate its action (agonist)
* Inactivating Na+ and Ca++ conductance in different channels.

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10
Q

What are the therapeutic uses of anticonvulsants?

A

Reduction of incidence, severity, and duration of seizures

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11
Q

What are the adverse effects of anticonvulsants?

A

Adverse Effects:
* Rapid cessation effect of administration of these drugs. (Rapidly removed by liver).
* Liver and serum enzymes induction
* Hepatotoxicity in dogs

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12
Q

What is the MOA of barbituates?

A

activation of GABA-gated Cl- channels

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13
Q

Phenobarbital is an _______.

A

oxybarbiturate

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14
Q

Pentobarbital is an ________

A

oxybarbiturate

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15
Q

Primidone is an analog of ______

A

phenobarbital

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16
Q

What is the MOA of Benzodiazepines?

A

Facilitating the inhibitory action of GABA
by binding to GABAA receptors

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17
Q

List the drugs classified as Benzodiazepines?

A

Diazepam
Midazolam
Clonazepam
Lorazepam

“Don’t Mind Little Christine”

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18
Q

What is the MOA of Hydantoins?

A

targeting sodium channels

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19
Q

Phenytoin is a ______ derivative

A

hydantoin

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20
Q

Valproic Acid is a derivative of?

A

carboxylic acid, via Cl- channels

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21
Q

List the anticonvulsant drugs considered to be “unconventional.”

A

Gabapentin
Levetiracetam
Felbamate
Zonisamide

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22
Q

Gabapentin: synthetic ____ analog acting via _____ of ____-gated ____ channels

A

GABA, inhibition, voltage, Ca++

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23
Q

Levetiracetam binds to a unique synaptic vesicle protein _________

A

2A (SV2A)

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24
Q

Felbamate: unknown, many mechanisms including inhibition of ____ and ____ channels

A

Na+, Ca++

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25
Q

Zonisamide: inhibition of ___ and ___ channels induction of _________.

A

Na+, Ca++, hyperpolarization

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26
Q

GABA is the major ______ NT in the CNS

A

inhibitory

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27
Q

GABA is considered our natural “_____-like” NT

A

Valium

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28
Q

GABA is produced mostly in the brain from _______ ____/_______
(needs Vitamin ___ for its synthesis)

A

glutamic acid, glutamate, B6

Found in these foods: Green tea, ? berries, tomatoes, etc.

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29
Q

GABA plays an important role in ?

A

behavior, cognition, and the
body response to stress. GABA controls fear and anxiety

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30
Q

The role of GABA is to _____ or _____ the activity of the neurons

A

inhibit,reduce

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31
Q

GABA-gated (_______ receptor) chloride channels mediate synaptic inhibition
by causing _____ ions to flow into the neuron causing its _______.

A

GABA A, chloride, hyperpolarization

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32
Q
A

GABA can bind to GABA A receptor, site for benzo, and barbituates.
Each receptor consists of 5 subunits that forms channel. When GABA like compoinds bind to receptor, channel opens, and allows charged chloride ions to pass through.
Binding of too many cells results in sedation. Neural inhibition?
Anatagonist: results in excitation of signal. EMAIL HER

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33
Q

What is the mechanism of action of barbituates?

A

Activation of GABA-gated Cl- channels

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34
Q

Phenobarbital is unique in that it usually produces _________ effect at _____ doses
than those necessary to cause pronounced CNS ______ (_____).

A

anticonvulsant, lower, depression, sedation

Depression can be in minimally severe cases.

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35
Q

What are the therapeutic uses of Barbituates?

A
  • For long-term control of seizures
  • Administered orally
  • It is not useful for terminating an ongoing seizure b/c the time span
    from administration until the onset of effect is too long (~ 20 min)
  • When given orally, its GI absorption is practically complete in all animals
    Peak levels occur in 4-8 hr after oral dosing in dogs.
36
Q

What are the adverse effects of Barbituates?

A
  • Sedation, polydipsia, polyuria, and polyphagia (signs of diabetes)
  • Dogs develop a tolerance to the sedative effects after 1-2 weeks
37
Q

Primidone is a _______.

A

deoxybarbiturate

38
Q

Primidone
Slow absorption after ____ administration in ____

A

oral, dogs

39
Q

PK: primidone is rapidly metabolized by the liver to ______

A

phenoparbutal
This drug is not actively ready until this occurs.

40
Q

85% of Primidone’s anticonvulsant activity is attributable to its conversion to __________

A

phenobarbital

41
Q

In cats, the metabolism of Primidone to phenobarbital is ____ (?).

A

slow, do not use in cats

42
Q

What are the adverse effects of Primidone?

A
  • Prolonged use in dogs may lead to decreased serum albumin and
    elevated serum concentrations of liver enzymes
  • Occasionally, serious liver damage
43
Q

What are the therapeutic uses of Pentobarbitol?

A
  • Will terminate seizures at a dose that produces anesthesia
  • Used for status epilepticus*
  • It has rapid onset (< 1 min) after IV injection and short duration of action
44
Q

What are the adverse effects of Pentobarbitol?

A
  • CNS depressant
  • May cause excitement during recovery from anesthesia
  • Irritating when administered perivascularly
45
Q

Status epilepticus is a seizure that last longer than ___ _____, or having ___ than 1 seizure
within ____ ____ period, without returning to a _____ level of consciousness ______ episodes.

A

5 min, more, 5 min, normal, between

46
Q

What is the MOA of Benzodiazepines (BDZs)?

A

facilitating the inhibitory action of GABA by binding to GABAA
receptors and evoking hyperpolarization of the neurons

47
Q

List the anticonvilsants classified as Benzodiazepines

A

Diazepam
Midazepam (ZolamR)
Clonazepam
Lorazepam

48
Q

What are Benzodiazepines used for?

A

They are used as anticonvulsants in all the domestic species

49
Q

Benzodiazepines are used to treat what specific type of seizures?

A

status epilepticus

50
Q

Benzodiazepines have a very limited use as a maintenance anticonvulsant in dogs,
because the tolerance development due to rapid drug metabolism.

A
51
Q

Benzodiazepines can be used as a _________ ______ in cats.

A

maintenance anticonvulsant

52
Q

What are the therapeutic uses of Diazepam in cats?

A

In cats, it is administered orally for seizure control

53
Q

What are the therapeutic uses of Diazepam in dogs?

A

In dogs, administered IV, is a drug of choice for the control of status epilepticus & cluster seizures

54
Q

What are the adverse effects of Diazepam?

A
  • Changes in behavior (irritability, depression and aberrant demeanor)
  • Cats may develop acute fatal hepatic necrosis
55
Q

What are the therapetic uses of Midazolam?

A
  • More potent than diazepam
  • Used for status epilepticus, muscle relaxant, tranquilizer, and appetite stimulant the
    same way as diazepam
  • PK: has shorter elimination t ½ of 77 min in dogs. Readily crosses BBB
56
Q

What are the adverse effects of Midazolam?

A
  • restless behavior, agitation
  • local irritation
  • mild respiratory depression
  • vomiting
57
Q

What are the therapeutic uses of Clonazepam?

A
  • The same as diazepam
  • Has limited value as a maintenance anticonvulsant because of
    rapid development of drug tolerance
58
Q

What are the adverse effects of Clonazepam?

A
  • Drug resistance
  • GI disturbance, including vomiting, hyper-salivation, and diarrhea/constipation
59
Q

What are the therapeutic uses of Lorazepam?

A
  • Orally for a short term at home treatment for dogs having cluster seizures
  • It may be safely used in patients with compromised liver function & in geriatric dogs
    because it does not produce active metabolites
  • In cats as a maintenance anticonvulsant
60
Q

What are the adverse effects of Lorazepam?

A
  • Increased appetite
  • Anxiety can occur early in therapy
61
Q

What is the mechanism of action for Hydantoins?

A

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

62
Q

What are the therapeutic uses of Hydantoins?

A
  • Because of its short half-life in dogs, its use may be impractical
  • Because of its lidocaine-like effects, phenytoin has been recommended for
    the treatment of digitalis-induced ventricular arrhythmias in dogs
63
Q

Valproic Acid is a derivative of _________ acid – ______ unrelated to other anticonvulsant

A

carboxylic, structurally

64
Q

What is the MOA of valproic acid?

A

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

65
Q

What are the therapeutic uses of valproic acid?

A
  • In dogs, oral administration is effective in controlling seizures, however
    its short t1/2 makes its impractical for long-term use
  • Can be useful as a second to forth line anticonvulsant in dogs
  • In cats, its clinical usefulness has not been evaluated
66
Q

What are the adverse effects of valproic acid?

A
  • GI toxicity: vomiting, anorexia, and diarrhea
  • Hepatotoxicity: liver failure in dogs
  • CNS effects: sedation, ataxia, behavioral changes
  • Dermatologic effects: alopecia, rash
  • Hematologic effects: thrombocytopenia, leukopenia, anemia
  • Pancreatitis
  • Edema
67
Q

What is the MOA of potassium bromiade?

A

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

68
Q

What are the therapeutic uses of potassium bromiade?

A
  • Administered orally, Br- is neither metabolized nor bound to plasma proteins,
    long t1/2, it may take up to 6 months to achieve stable plasma concentrations,
    eliminated by the kidneys
  • Used in combination with barbiturates & BDZs to treat refractory seizures in dogs
  • Not recommended in cats
69
Q

What are the adverse effects of potassium bromiade?

A
  • Transient sedation at the beginning of therapy
  • GI toxicity: nausea, vomiting, anorexia, and constipation
  • Polydipsia, polyuria, polyphagia, lethargy, irritability, and aimless walking
  • Pancreatitis
  • Severe asthma in cats
70
Q

Gabapentin is a synthetic _____ analog that can cross ____ to exert its anticonvulsant effect

A

GABA, BBB

71
Q

What is the MOA of Gabapentin?

A

Unknown

72
Q

What are the therapeutic uses of Gabapentin?

A
  • Administered orally
  • Used as adjunctive therapy for refractory of complex partial seizures
  • Treatment of chronic pain in dogs and cats
73
Q

What are the adverse effects of Gabapentin?

A
  • Sedation, Ataxia
  • Mild polyphagia
  • Abrupt discontinuation of gabapentin may cause seizures
74
Q

Which compound is this?

A

GABA

75
Q

Which compounds is this?

A

Gabapentin

76
Q

What is the mechanism of action of Levetiracetam?

A

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

77
Q

What are the therapeutic uses for Levetiracetam?

A
  • Administered orally
  • Used as adjunctive therapy for refractory canine epilepsy
  • Well tolerated in dogs and cats
78
Q

What are the adverse effects of Levetiracetam?

A

Adverse effects are mild
* GI disturbances: vomiting, anorexia
* Changes in behavior, drowsiness
* Abrupt discontinuation of levetiracetam may cause seizures

79
Q

What is the MOA of Felbamate?

A

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

80
Q

What are the therapeutic uses of Felbamate?

A

Administered orally
* Used as adjunctive therapy for refractory canine epilepsy
* Used as sole anticonvulsant for patients with local and generalized seizures
* Particularly useful in cases with brain tumor or cerebral infarct (due to no-sedation effect)

81
Q

What are the adverse effects of Felbamate?

A
  • Liver dysfunction in dogs
  • Rare: reversible bone marrow depression (condition: thrompocytopenia or leucopenia) in dogs
  • Rare: generalized tremor and/or keratoconjunctivitis sicca (dry eye) in dogs
82
Q

What is the MOA of Zonisamide?

A

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

83
Q

What are the therapeutic uses of Zonisamide?

A
  • Administered orally, twice a day
  • Used as adjunctive therapy for refractory canine epilepsy (less often in cats)
  • Used as sole anticonvulsant for patients with local and generalized seizures
  • Particularly useful in cases with brain tumor or cerebral infarct (due to no-sedation effect)
84
Q

What are the adverse effects of Zonisamide?

A
  • High safety margin in dogs and cats
  • Rare: Sedation, ataxia, and anorexia
85
Q

What is the NB of Zonisamide?

A

Cost can be a problem for dogs
Not enough data for cats

86
Q

What are the symptoms of seizures in dogs?

A

Intro to Pharmacology (31 decks)

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