antiseizure Flashcards
is epilepsy just 1 disorder
no, it encompasses many disorders
what characterizes epilepsy
recurrent seizures (chronic disease) - heretogenous (several root causes) symptom complex
what is a seizure
finite period of brain dysfunction resulting from abnormal discharge of cerebral neurons
how do you figure out the degree of neural activity with electroencephalograms
you compare between pairs of electrodes (this allows a degree of localization of neuronal activity)
what are all seizures cause by
an imbalance between excitation and inhibition in brain
what are 2 types of partial seizures
simple and complex
what characterizes partial seizures
they have a localized onset
what are simple seizures like (3)
abnormal discharge with minimal spread - consciousness preserved
what are complex seizures like (4)
localized discharge with wide bilateral spread, usually limbic, loss of consciousness
is consciousness preserved in complex partial seizures
no
what is an aura
a sense that the seizure is starting
what are automatisms and when do they happen (which seizure type)
fragmented behaviours (like lip smacking, swallowing…) - complex partial seizures
can you have a partial seizure that then generalizes to a tonic clonic seizures
yes
what are 2 types of generalized seizures
generalized tonic clonic and absence (petit mal)
what do generalized tonic clonic seizures look like
full blown attack with rigidity (tonic), followed by alternating relaxation and rigidity, and jerking of body (clonic)
what do absence seizures look like
staring, altered consciousness, sometimes mild jerking of eyelids and extremeties
whats a heterogenous syndrome
where there are many diff symptoms possible, not just one thing
how do most of the anti-seizure drugs nowadays work (3)
reduce sympathetic excitation, enhance synaptic inhibition, block ion channels
what do anti-seizure drugs do to the sodium channel (2)
prolong inactivation to make repetitive firing more difficult
which kind of seizures do drugs that target Na+ channels work well for
partial seizures
which 4 drugs affect sodium channels
phenytoin, carbamazepine, lamotrigine, topiramate
how do drugs that target Ca2+ channels work
suppress activity of t-type Ca2+ channels, stopping oscillatory bursts
give 3 drugs that supress T-type Ca2+ channels
ethosuxamide, valproate, lamotrigine
what does ethosuxamide do
block t type ca channel to stop oscillatory behaviour/ bursts
what kind of seizure are ca2+ channel inhibitors good for
absence (eg. ethosuxamide)
what do anti-seizure drugs want to do to GABA A receptors DIRECTLY
potentiate their action (GABA binds, channels open for longer)
what do anti-seizure drugs want to do to GABA A receptors INDIRECTLY
reduce GABA uptake or metabolism
which 2 drugs directly potential GABA A receptor action by either acting as an agonist/positive allosteric modulator
benzos and barbs
which 3 drugs indirectly increase GABA levels by reducing the uptake/breakdown of GABA
gabapentin, tiagabine, vigabatrin
which 2 drugs reduce glutamate action
phenobarbital and topiramate (they reduce excessive excitation)
where does phenytoin act (which receptors)
Na+ K+ Ca++
how does phenytoin do use dependent block of Na+ channel
it binds preferentially to inactive state of channel
what does phenytoin do to Ca+ AND what does this cause
blocks influx so there is less ca-dependent secretory processes
which kind of seizures in phenytoin best for
partial and generalized tonic clonic
which 3 drugs are good for partial and generalized seizures
phenytoin, carbamazepine, phenobarbital
what is the action of carbamazepine
similar to phenytoin (blocks K+ Ca+ Na+)
what drug is used for trigeminal neuralgia
carbamazepine
how does phenobarbital work (2)
suppresses (heavily) excitatory transmission, potentiates GABA A receptor activation (since it’s a barbituate)
what are 3 main drugs just for generalized seizures
ethosuximide
valproid acid
benzos
how does ethosuximide work
supresses T type Ca++ channels
what is the type of seizure that ethosuximide is best for
absence seizures
what is the mechanism of action for valproic acid
increase neuropeptide Y levels in brain (an antiseizure peptide)
what kind of seizures is valproic acid good for (3)
absence, myoclonic, primary general tonic clonic
when are benzos good for seizures
for acute seizure (status epilepticus), not for long term
why dont you want to use benzos long term for seizures (2)
tolerance and sedation
what is the mechanism of action of vigabatrin (2)
irreversible inhibitor of GABA-transaminase (breaks down GABA) AND inhibits GABA transporter
what kind of seizures is vigabatrin good for
partial seizures
what is the mechanism of action of tiagabine
GABA uptake inhibitor (GAT-1)
what is the mechanism of action of lamotrigine
like phenytoin on Na+, also Ca+ (blocks)
what kind of epilepsy is lamotrigine best used for
partial epilepsy and absence
what is the main drawback for lamotrigine
rash can be life threatening especially for kids!!!
what is the mechanism of action of felbamate
blocks NMDA on glycine sites (NR1 and NR2B)
what kind of seizure is felbamate best for
focal/partial
what are 2 really bad adverse effects for felbamate
aplastic anemia and severe hepatitis
what is the mechnamism of action for topiramate
inhibits Na+ channels, potentiates GABA effects, inhibits AMPA receptors (Glu receptor)
what is the unique structure like of topiramate
substituted monosaccharide
