Anticonvulsants Flashcards
What does tonic mean in relation to seizures?
30 seconds The animal will fall and become unconscious Limbs are rigidly extended Opisthotonos Apnea
What does clonic mean in relation to seizures?
1-2 minutes
Clonic limb movements in the form of running or paddling
Chewing movements of the mouth
Autonomic activity
Why is it commonly recommended to spay bitches if they are epileptic?
Estrogen can lower the threshold for seizures, so we spay them to remove estrogen
What is the goal in using an anticonvulsant in an animal prone to seizures? That is, why is completing stopping all seizure activity not attempted?
The goal is reduction in frequency of seizures: Duration of seizures, Severity of seizures
There is a risk for status epilepticus if you try to completely stop seizures
CRIs of either diazepam or midazolam are sometimes used in refractory seizure cases while hospitalized. How do these two drugs differ relative to their binding to soft plastics such as IV bags and lines and their solubility in iv fluids?
Diazepam:
Absorbs to soft plastics
Limited solubility in most IV fluids
Midazolam:
Does not bind to plastics
Water soluble
Know that diazepam, unlike in the dog, can be used in cats to prevent seizures. What type B adverse reaction in cats however is diazepam sometimes associated with if used repetitively?
Severe hepatitis
What is bromide primarily removed by? Does it require a loading dose?
Kidney
Loading dose is necessary
What is gabapentin primarily removed by? Does it require a loading dose?
Kidney
No loading dose
What is levetiractem primarily removed by? Does it require a loading dose?
Kidney
No loading dose
What is phenobarbital primarily removed by? Does it require a loading dose?
Liver
Loading dose is necessary
What is zonisamide primarily removed by? Does it require a loading dose?
Liver
No loading dose
Which anticonvulsant has the longest half-life in the dog?
Bromide (28 days)
How should you stop treatment with phenobarbital?
Wean off drug, 25% decrease in dose every few weeks
Know that you cannot abruptly stop phenobarbital in an animal that has been on it for a substantial period of time (months). In such cases the dose should be tapered over time.
25% decrease in dose every few weeks. Can discontinue ≤ 10 mcg/ml
Why is primidone no longer recommended as an anticonvulsant in veterinary medicine? What related drug should instead be used?
More expensive and more likely to cause side effects than phenobarbital
Phenobarbital should be used instead
How long does it take intravenous phenobarbital to reach its peak effect?
Maximum effect around 20 minutes post-dosing
“Liver function tests” are often recommended for animals on chronic phenobarbital. Name two such tests.
Bile acids or ammonia challenge
What endocrine test can show false results (indicate disease when it is not present) for animals receiving phenobarbital?
Thyroid testing
Name the anticonvulsants appropriate for use in cats.
Oral Diazepam Phenobarbital Zonisamide Gabapentin Levetiractem
Are benzodaizepines appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Status epilepticus
Is bromide appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Maintenance
Is gabapentin appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Maintenance
Is ketamine appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Status epilepticus
Is levitarcetam appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Both
Is phenobarbital appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Both
Is propofol appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Status epilepticus
Is zonisamide appropriate to break an on going seizure (status epilepticus), used to prevent additional seizures (maintenance), or both?
Maintenance
What effect does diet have on the disposition of bromide?
Bromide comes in salts of potassium or sodium, so if you use potassium they should be on a sodium restricted diet and if you use sodium they should be on a potassium restricted diet
What route(s) of administration is (are) used to give loading doses of bromide if the animal cannot receive it orally at that time?
Rectally
What non-intravenous route(s) are used for owner to give diazepam or midazolam at home to stop an ongoing seizure?
Diazepam: rectal
Midazolam: intranasally (risk to owner) or IM. Potentially rectally but it’s not as effective as diazepam
Bromide for anticonvulsant use must be compounded. Why is the dose different if using sodium bromide versus potassium bromide? Why are solutions of bromide preferred over capsules containing the crystals?
The dose of sodium bromide should be 15% less than the dose used for potassium bromide because there is a higher concentration of bromide in the sodium salt
With the solution, it is easier to adjust the dose, it is cheaper, and it is easier to give to the animal than capsules.
Though classified as an anticonvulsant, name two other extra-label uses of gabapentin in cats.
Analgesic in neuropathic pain and manages aggression
