Neuro: Clinical

Question 1

ACVIM 2015 recommendations on when to start AEDs

Answer 1

1. Known cause: Structural disease is present or prior brain injury is known.
2. Acute severe seizures: Status epilepticus (>5 minutes duration or >3 seizures within 24 hours)
3. Chronic seizures: >2 seizures within 6 months
4. Severe post-ictal period

Question 2

ACVIM 2015 recommendations for AEDs that may be used as mono therapy (order of preference)

Answer 2

1. Phenobarbital, Imepitoin, 2. KBr
2. Zonisamide, levetiracetam
3. Primidone

Question 3

ACVIM 2015 recommendations for AEDs that may be used as add on therapy (order of preference)

Answer 3

1. Phenobarbital, levetiracetam, KBr, Zonisamide
2. Imepitoin
3. Primidone

Question 4

Phenobarbital: MoA

Answer 4

Enhance the effectiveness of the GABAa receptor.

May also inhibits release of other neurotransmitters such as Act, nEP and glutamate.

Question 5

KBr MoA

Answer 5

Bromide competes with chloride transport thus resulting in membrane hyperpolarisation.

Question 6

Primidone MoA

Answer 6

85% is metabolised to phenobarbital

No benefit to using this over phenobarbital.

Question 7

Imepitoin MoA

Answer 7

Partial agonist of the BNZ receptor of GABAa receptor.

Question 8

Levetiracetam MoA

Answer 8

Largely unknown but may bind to SV2A which is a presynaptic protein

Question 9

Zonisamide

Answer 9

May reduce sodium and T-type calcium channel opening on the post-synapse of excitatory neurons

Question 10

When might trough sampling of phenobarbital be useful?

Answer 10

When patients seizure close to the next scheduled dose of the drug.

Question 11

When should phenobarbital monitoring be performed following a start/change in therapy?

Answer 11

2w (steady state concentration)
6w (steady state of clearance - d/t liver enzyme induction)
then q6m and 2w after dose changes

Question 12

When should KBr monitoring be performed

Answer 12

• 6-12 weeks
• annual basis
• if >3 seizures occur before next evaluation
• signs of toxicity
• perform >2 hours post dosing

Question 13

What consideration should be made regarding dosing of levetiracetam when using this alongside phenobarbital?

Answer 13

May need higher doses due to phenobarbitals metabolic effects.

Question 14

Which enzyme metabolises Zonisamide?

Answer 14

CYP3A4

Question 15

Which AED drugs are affected by phenobarbital administration?

Answer 15

Levetiracetam and zonisamide

Question 16

TDM recommendations for zonisamide

Answer 16

• 1-2 weeks following initiation or dose adjustment
• if a change in seizure frequency occurs
• evaluation of both peak and trough is recommended

Question 17

AED that may result in idiosyncratic blood dyscrasias?

Answer 17

Phenobarbital (immune mediated)

Question 18

AED that may result in pancreatitis?

Answer 18

KBr

Question 19

AED resulting in GI irritation

Answer 19

KBr

Question 20

AED that may result in idiosyncratic renal and hepatic disease

Answer 20

Zonisamide (causes RTA)

Question 21

AED that may result in superficial necrolytic dermatitis

Answer 21

Phenobarbital

Question 22

How is KBr toxicity treated?

Answer 22

Saline diuresis which will enhance renal excretion

Question 23

What diagnostic test results can be affected by Zonisamide?

Answer 23

Thyroid - may result in reduction of TT4. (fT4 and TSH should remain normal)

Question 24

Which of the following dietary strategies may be effective in reducing seizure frequency in dogs:

• MCT
• Omega-3 supplementation
• Ketogenic diet

Answer 24

MCT diet

Ketogenic diet is helpful in humans.