Seizures & Epilepsy pt 2 Flashcards
phenobarbital for seizure management - pros and cons
PROS:
- Efficacious
- Cheap
- Q12h dosing
- Steady state = 3wks
- T1/2 = 30-90h (dog)
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CONS:
- PU, PD, PP
- Sedation x 14d
- increased CyP450s
- Potential dose-related liver toxicity
- ± idiosyncratic bone marrow suppression
KBr for seizure management - pros and cons
PROS:
- Efficacious
- Cheap
Q24h dosing
- T1/2 = 24d (dogs)
- T1/2 = 10d (cats)
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CONS:
- PU, PD, PP
- Sedation x 14d
- Steady state = 3mo
- Steady dietary NaCl
- ± pancreatitis
- Fatal to 50% cats
Levetiracetam for seizure management - pros and cons
PROS:
- Efficacious
- Minimal adverse effects
- Steady state = 2-3d
- T1/2≅ 3h (dog & cat)
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CONS:
- Expensive
- Sedation x 2-3d
- Q8h dosing (except SR)
- Higher dose with PB
Gabapentin / Pregabalin for seizure management - pros and cons
PROS:
- Efficacious add-on
- Minimal adverse effects
- Steady state = 1-2d
- G T1/2 = 3h (dog)
- P T1/2 = 7h (dog)
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CONS:
- expensive
- sedation x 1-2d
Zonisamide for seizure management - pros and cons
PROS:
- Efficacious add-on
- Cheap
- Q12h dosing
- Minimal adverse effects
- Steady state = 3-4d
- T1/2 = 13h (dog)
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CONS:
- Only via compounding in Canada
- Sedation x 2-3d
- Inappetance
- + Pheno = 2 x dose
- Idiosyncratic reactions:
> hepatic necrosis
> renal tubular acidosis
Nonpharmacologic Tx for seizures? what things do people try?
- Vagal Nerve Stimulation: NO?
- Diet: ketogenic/omega-3 NO vs MCT YES?
- Acupuncture: NO
- Homeopathy: NO
cannabidiol (CBD) as seizure treatment in dogs - efficacy? effects and adverse effects?
- unknown efficacy
- adverse effects: nausea, V+/D+, lethargy, hyperesthesia, muscle tremors, ataxia
- unknown dosage
- T = 4.2h (dogs)
- no vet drugs
Will a Seizure Kill? how?
- if status epilepticus, possible
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Potential physiologic complications?
– Respiratory, cardiovascular, renal, autonomic, metabolic, neurologic
What is Status Epilepticus? consequences?
5 min or ≥ 2 seizures with incomplete recovery between
– Failure of seizure termination
– Initiation of mechanisms > abnormally prolonged seizures (> t1)
- the one time that a seizure can kill > resp and cardiovsacular overload, autonomic dysfunction, etc etc etc
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May have long-term consequences (> t2), incl: neuronal death, injury & alteration of neuronal networks, deficits
Stages of Status Epilepticus
Stage 1: Impending
- 5-10 min
- neurotransmitter release / imbalance
- ion channel opening / closing
- First line treatment: likley responsive
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Stage 2: Established
- 10-30 min
- likely not resposnive to first line treatments, but responsive to second line
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Stage 3: Refractory
- > 30min
- responsive to third line treatments
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Stage 4: Super-refractory
- gene expression alterations
- first second and third line treatments: minimally to non-responsive
status epilepticus tx rule of thumb
Large dog = 3mL diazepam
Medium dog = 2mL diazepam
Small dog = 1mL diazepam
Toy dog/cat = 0.5mL diazepam
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Midazolam 0.2 mg/kg IN
first line, second line, third line treatments for status epilepticus
first line
- midazolam IN, IV, or diazepam IV
+/- midazolam CRI
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second line
- levetiracetam IV + phenobarbital IV +/- fosphenytoin IV
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third line
- kketamine iV, CRI
+/- dexmedetomidine IV, CRI
+/- propofol +/- phenobarbital +/- inhalant anesthesia
Drug-resistant Epilepsy
- when do we consider this to be the case?
QoL compromised by seizure severity or frequency, or medication adverse effects
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Considerations (human):
– Lack of response to 2 drugs
– ≥1 seizure/mo
– Duration ≥1yr
What is Nonconvulsive SE? when does it occur?
- BAD
- No outward clinical signs of seizure
> Comatose vs non-comatose
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BUT, EEG shows ongoing seizure activity: electromechanical dissociation
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Occurs when: - Prolonged SE
- Sufficient drugs to minimize visible movement, but insufficient to stop electrical seizure in brain
