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75 Cards in this Set
- Front
- Back
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Seizures
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abnormal electrical activity in the brain that causes altered behavior
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epilepsy
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disease process of having multiple seizures over time - not all animals that have seizures have epilepsy
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Status epilepticus
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series of sezures with no post-ictal phase
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Anticonvulsant mechanisms
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increase inhibitory neurotransmitters (GABA) decrease excitatory neurotransmitters, alter electrolyte conductance
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GABA agonists do what
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increase flow of chloride into the cell
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GABA agonists
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Phenobarbital
Diazepam Clonazepam Clorazepate Pentobarbital |
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NMDA receptor antagonist
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Felbamate
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Anticonvulsant MOA unclear
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Gabapentin
Levetiracetam Zonisamide Potassium Bromide |
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Phenobarbital is a
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GABA Agonist
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Diazepam
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GABA agonist
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Clonazepam is a
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GABA Agonist
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Clorazepate is a
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GABA Agonist
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Pentobarbital
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GABA Agonist
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NMDA receptor antagonist
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Felbamate
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What 3 durgs treat status epilepticus
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Diazepam, Phenobarbital, Pentobarbital (in this order)
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Phenobarbital side effects
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sedation, PUPD, ataxic
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Gabapentin MOA
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blocks Ca channels and causes inhibition
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Zonisamide MOA
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Blocks Na channel and Ca channel
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Anticonvulsant Benzodiazapine
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Clonazepam
Clorazepate, Diazepam |
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Phenytoin
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not effect anticonvulsive
Blocks Na channels |
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Barbituate anticonvulsant
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Primidone - metabolized into phenobarbital
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Which has a shorter half life Phenobarbital or Potassium bromide?
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Pheno 56 - 102 hrs
Bromide - 14 - 21 days Phenobarbital |
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Phenobarbital mechanism
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binds GABA receptor
increases Cl conductance raises seizure threshold |
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Phenobarbital side effects
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sedation, PU/PD, lethargy, ataxia, elevated ALT, ALP, hepatotoxicosis,
Hepatocutaneous disease |
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Phenobarbital induces
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CytP450
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Primidone is a ____ and has what mechanism
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barbiturate
GABA inhibitory action Metabolized into phenobarbitol. |
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Phenytoin mechanism
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alters electrolyte conduction - blocks influx of Na, and decreases Ca influx in presynaptic cell thus decreasing NT release
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Diazepam is a _____ and has what mechanism
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benzodiazepine
potentiates inhibitory NT, alters electrolyte conductance Binds different GABA site than Phenobarb. |
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Diazepam can also be used for
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muscle relaxer, anxiety, aggression, behavior disorders in animals, stimulation of appetite in anorexic cats
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Clanazepam is a _______ and has what mechanism
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Benzodiazapine
Last resort when Phenobarb ineffective Alternative to Diazepam in cats |
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Felbamate mechanism
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NMDA receptor antagonist.
less sedation but more expensive |
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Gabapentin mechanism
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Blocks calcium-dependent channels
reduces NT release from presynaptic neurons |
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Levetiracetam
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preferred for refracotry epilepsy
May modulate Ca depedent NT Binding in CNS sedation ataxia vomiting |
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Zonisamide
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Blocks Na and Ca channels (t type), blocks Na influx,
sedation, ataxia, vomiting |
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Potassium bromide
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Interferes with Cl transport across membrane
CNS depression, weakness, ataxia, sedation, pruritis |
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Focal or partial seizures characteristics
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simple
complex may become generalized |
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Primary epilepsy
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inherent biochemical abnormality in the brain
lowered seizure threshold |
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Secondary epilepsy
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increased cerebrocortical excitability
intracranial (symptomatic) extracranial (reactive) |
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Idiopathic Epilepsy clinical signs
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Usually young (1 - 5 years old)
Labs, Goldens, GSD, Viszla, Husky Seizures generalized most do not present in status Seizures tend to occur with changes in sleep-wake cycles |
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Tentative diagnosis and treatment of idiopathic Epilepsy can be diagnosed if
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blood work normal
no history of toxin exposure no inter-ictal neurological deficits usually less than 2 -3 events a year |
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Intracranial causes of epilepsy includes
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Inflammation/infection
Bacterial Rickettsial Protozoal Viral Helminths Fungal |
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Intracranial inflammatory epilepsy classifications
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GME
NME EME |
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Intracranial malformative causes of epilepsy
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Hydrocephalus
Hydrancephaly Chiari Vascular Dandy-Walker |
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Extracranial causes of epilepsy
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Electrolyte imbalances
Hypoglycemia Endocrine Toxins Liver Renal Nutritional Energy deprivation |
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Status epilepticus
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Continuous seizures > 5 min or > 2 seizures between which there is incomplete recovery2 seizures in a 24 hours period w/o evidence of SE
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Dangers of Status Epilepticus
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hyperthermia
Hypoxia hypotension energy deprivation metabolic acidosis hyperglycemia Arrhythmia |
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Phenobarbital is eliminated
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via liver
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Phenobarbital half life
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24 - 48 hours - low dietary protein/fat shorten
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Phenobarbital contraindicated in
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animals with drugs on p450 metabolism
animals with known hepatic dysfunction |
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Phenobarbital therapeutic range
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15 -45 mcg.ml
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Adjust phenobarbital levels based on
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blood drug levels not oral dosage
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Potassium Bromide T 1/2 is
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20 /26 days
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Potassium Bromide is eliminated via
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the kidney
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Potassium Bromide is contraindicated in
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renal disease
Cardiac disease CATS! |
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Diazepam is a
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GABA receptor agonist
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Diazepam t 1/2
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3 - 4 hours
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Diazepam is contraindicated in
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cats due to hepatoxicity
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Phenytoin MOA
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Na channel inhibition
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Phenytoin t 1/2
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1.5 hours
limited maintenance drug |
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Phenytoin is mostly used for
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pulse therapy
for clusters |
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Felbamate MOA
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NMDA receptor blockade
GABA agonism |
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Felbamate t 1/2
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5 -6 hours
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Felbamate not used because
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severe hepatotoxicity
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Zonisamide MOA
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blocks T-type Ca and Na channels
enhanced GABA activity Glutamate block |
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Zonisamide t1/2 is
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15 hours
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Zonisamide elimination
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hepatice
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Gabapentin
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Ca and Na channel blockade major mechanism
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Gabapentin t 1/2
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1 - 3 hours
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Gabapentin elimination
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70 % urinary
30 % liver |
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Gabapentin side effects
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mild sedation
slight weight gain mild ataxia |
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Gabapentin used for
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partial onset seizures
refractory seizures |
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Levetiracetam MOA
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SVA2 blockade
Possible GABA and blycine channel agonism |
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levitiracetam effect does not correlate to
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blood level
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Levetiracetam seems to have an effect in
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refractory cats
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If money is not object chose which anticonvulsant
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Levetiracetam or zonisamide
Gaba pentin as adjunct |
