Seizure Disorders Flashcards
- no loss of consciousness, localized to specific area of brain
- cortical focal
- increasing electrical activity at a focus followed by synchronization of surrounding neurons, abnormal firing can spread to adjacent neurons
partial seizures
focal seizure activity in one hemisphere spreads throughout brain, involves LOC
tonic clonic (grand mal) seizure
- brief interruptions of consciousness manifested as motionless starting
- common in school aged children
- abnormal synchronization of thalamocortical and cortical cells, activation of T-type calcium channels that are normally active during sleep
absence (petit mal) seizures
greater than 5 minutes without regaining consciousness
status epilepticus
prolonged activation of ____ channels reduced the ability of neurons to fire at high frequencies
sodium
inhibition of _______ channels tend to be efficacious for absence seizures
T-type calcium channels
- enhance GABAergic activity
- DOC for status epilepticus
- good for infantile myoclonic, tonic clonic, absence seizrues but onlly for 2-3 weeks due to tolerance
- adverse: sedation
diazepam, clonazepam
- increase chloride ion channel flux by increasing channel open time, decrease glutamatergic neurotransmission
- DOC for tonic clonic
- very sedating
- Stevens Johnson, abrupt withdrawal –> status epilepticus, induces microsomal enzymes, possible teratogen
phenobarbital (barbiturate)
- converted to phenobarbital and PEMA, parent and products are active as anticonvulsant
- drowsiness, ataxia, n/v, rash, diplopia, blood dyscrasias
- effective in patients not responding to phenytoin or phenobarbital
- give in combo with phenytoin but never phenobarbital
primidone
- prolong inactivation of sodium channels and decrease glutamate release
- DOC for tonic clonic and partial
- less sedating than barbiturates
- drug interactions: induce P450s, vit D deficiency, highly protein bound
- saturation, small dose increases can result in toxicity
- adverse: dipolopia, ataxia, n/v/rash, hyperplasia of gums, hirsutism, teratogenic
phenytoin (hydantoin)
- broad spectrum, increases inactivation of Na channels, inhibits T type calcium channels, enhances GABA, modifies AA metabolism
- DOC for tonic clonic
- hepatotoxicity, esp in children <2yo
- sedation uncommon, IV prep for status epilepticus
- **P450 inhibitor
valproic acid
- increase inactivation of sodium channels, decreases release of glutamate
- safe, nontoxic, non sedating
- induces microsomal enzymes, blood dyscrasias
carbamazepine
- increases inactivation of sodium channels, may inhibit T type calcium channels and decrease glutamate release
- effective in partial and absence seizures
- GI, nausea, sedation, diplopia, rashes
- valproic acid increases half life
- add on, approved as monotherapy
lamotrigine
- increases inactivation of sodium channels, enhances GABA and decreases glutamate activity
- effective for partial and generalized tonic clonic, perhaps absence
- sedation, mental dulling, abnormal vision, parasthesia, decreased serum bicarb
- decrease efficacy of oral contraceptives
- add on, monotherapy
topiramate
- add on for partial seizure
- modifies synaptic release of GABA by binding to synaptic vesicular protein SV2A
- agitation, drowsiness, asthenia, muscle weakness, dizziness
levetiracetam
enhances slow inactivation of sodium channels, add on for partial seizures
lacosamide
- add on: decrease glutamate release by binding to voltage gated calcium channels
- effective in refractory partial seizures when used in combo with other drugs
- in combo with carbamazepine or phenytoin
- sedation, movement disorders, leukopenia, edema, behavior changes in children
gabapentin/pregabalin
inhibits GABA reuptake, add on for partial and tonic clonic seizures
tiagabine
increases inactivation of sodium channels, drowsiness and anorexia, add on
zonisamide
enhance K channel opening, add on
ezogabine
AMPA glutamate receptor antagonist
perampenel
add on, pro drug, voltage gated sodium channel blocker
eslicarbazepine
- treats absence seizures
- inhibits T type calcium channels
- DOC
- patients may develop tonic clonic seizures, so admin with primidone or phenytoin (exacerbates when used alone)
ethosuxamide
-used for absence seizures that are refractory to other drugs
methsuxamide
very limited use for absence seizures, many adverse effects
trimethadione
