Seizure Medications

Question 1

Describe the mechanism of action, blood work changes and side effects of phenobarbital

Answer 1

Class : barbiturate medication.
Metabolism : metabolized by the liver, causes an upregulation of CP450 —> metabolized faster and faster overtime so need to increase the maintenance dose.
Steady state : takes 10-14 days to reach.
Serum levels : check 2 weeks after starting the medication and the every 6 to 12 months. Over 35 is toxic
Bloodwork change: can increase ALP and falsely decrease T4.
Side effects : can cause hepatotoxicity, blood dyscrasias and moist/necrotic dermatitis.
First line of treatment

Question 2

Describe the mechanism of action, blood work changes and side effects of levetiracetam

Answer 2

Class: racetam anticonvulsivant.
Metabolism: renal excretion
Steady state : 24 hours.
Serum levels: we usually don’t check unless we suspect toxicity —> if so look at peak (2h post pill) and through (right before pill)
Bloodwork change : none
Less effective and phenobarbital so we typically use phenobarbital first.

Question 3

Describe the mechanism of action, blood work changes and side effects of potassium bromide.

Answer 3

Class : salt
Metabolism : renal excretion.
Steady state : takes 3 months to reach
Serum levels : goal 1-3 mg/dL
Bloodwork changes : pseudohyperchloremia —> machine can’t tell the difference between bromide and potassium.
Side effects : mucositis and colitis (rectal administration)
N.B> need a stable diet ; risk of idiosyncratic fatal penumositis in cats.

Question 4

Describe the mechanism of action, blood work changes and side effects of zonisamide

Answer 4

Class : sulfa drug (different from other sulfa in regards to hypersensitivity reactions)
Metabolism : liver
Serum levels : we don’t check them unless we are worried about toxicity —> peak and through levels
Possible side effect : can increase ALP +/- other liver values, hepatotoxicity and urinary calculi. Risk of hypersensitivity reaction and teratogenic in dogs.