Anticonvulsants - egleton Flashcards
abnormal EEG is indicates what
Seizure
Generalized tonic-clinic seizures so frequent that another seizure occurs before the patient returns to normal consciousness from the postictal state
- how severe is this? how?
Status Epilepticus
medical emergency and high mortality rate
hypoxia leads to brain damage
What is the treatment for Status Epilepticus
IV Benzodiazapams
followed with IV Phenytoin/Fosphenytion ( prevent reoccurance)
what treatment is used for status Epilepticus if refractory? and if this doesn work? Any extra support
more phenytoin and more BCZ
- Barbituates ( phenobarbital/phentobarbtial/Midazolam/propofol)
- may need respiratory support
what are 3 parts of a history of seizure
aura
ictus: seizure itself
Postictus
how is epilepsy diagnosis made
history with electrical studies
what are 3 MOA for antiepileptic drugs
- inhibition of sodium and calcium influx
- augmentation of inhibitory GABA neurotransmission
- inhibition of excitatory glutamate neurotransmission
MOA for Phenytion
- inhibition of seizure spread: blockade of Ca influx, enhances Cl- IPSPs
- suppression of epileptic focus: affinity for inactivated Na channels at depolarized membrane potentials, stimulates Cl- mediated IPSP
Use of Phenytion
Initial treatment for: Absence Epilepsy Atonic Seizures
effective treatment for: generalized tonic-clonic seizures, partial and status epiepticus
if Phenytoin is give IM what happens
crystallization and possible muscle necrosis
when the hepatic hyroxylation system becomes saturated small increases in dose of Phenytoin causes what
large increase in the plasma concentration of drug
Side effects of Phenytoin
Hirsutism gingival hyperplasia nystagmus Steven-Johnson syndrome Hematological reactions
what allergic reactions to Phenytoin require cessation of therapy
Hematological reactions
Steven-Johnsons
how is Phenytoin administered for cardivascular collapse
IV
what are fetal abnormalities of Phenytion
pregnancy category D
heart malformations
what is the prodrug of Phenytion
Fosphenytion
MOA for Carbamazepine
unknown
Carbamazepine 2nd line of drug for what
2nd: generalized tonic-clonic seizures
complex partial seizures
other: may make myoclonic seizures worse
trigeminal neuralgia
Carbamazepine has an autoinduction of metabolism of what
CYP 1A2 / 2C/ 3A
when does the rate of metabolism increase for Carbamazepine? 1/2 lives?
first 4-6 weeks
30hr = naive patient
10-20 hours - after few weeks
what are side effects of Carbamazepine
G.I. upset
vertigo
Hematological disorders
hepatoxicity
MOA for PHenobarbital
enhances the GABA mediated Cl-flux that causes membrane hyperpolarization
- older drug
Side effects of Phenobarbital
sedation
addiction
rashes
Drug interaction of Phenobarbital
induces various CYPs
addictive with other CNS depressants
Valproic acid increases Phenobarbital blood levels
Primidone
antiepileptic drug
MOA for Valproic acid/Divalproex
Interacts with GABAergic:
blocks both Na and K channels and T-type calcium channels
uses for Valproic acid/Divalproex
absence seizures refractory to ethosuximide
bipolar
what is so great about Valproic acid/Divalproex
well absorbed in gut
low molecular weight fatty acid
“sprinkles”
Side effects of Valproic acid/Divalproex
Alopecia
hepatic failure
decrease in platelet and clotting function
for Valprioc acd/Divalproex who does hepatic failure have the greatest risk for
under 2 years
what is drug interaction of Valproic acid/Divalproex
inhibits P450s
displaces phenytoin from plasma protein
decreases elimination of Phenytoin
Should you take Valproic acid/Divalproex while pregnant or child bearing age
no
what is the use for Ethosuximide
absence seizures - only indication
MOA of Ethosuximide
blocks T-type Ca channels
what are side effects of Ethosuximide
GI
CNS depression
Rashes
Blood dyscrasia
which Lorazepam if given as an IV agent for status Epilepticus
Clonazepam
Diazepam
MOA for Lorazepams
action on Benzodiazepine binding site of GABAa receptor complex: promoting GABA action
what is Gabapentin used for
diabetic neuropathy
what are side effects of Gabapentin
CNS: dizziness
weight gain
MOA for Lamotrigine
inhibits voltage-sensitive Na channels
may inhibit Ca channel
what is the side effect of Lamotrigine? how can this be reduced
severe steven-johnson and potentially life threatening
-titrating dose
What are side effects for Topiramate
renal stone formation
paresthesias ( carbonic anhydrase inhibitor) can be used in treatment of IICH
MOA for OXacarbazepine
blocks voltage dependent Na channels
what are other uses for Levetriacetam
migraine
Side effects of Oxcarbazepine
Hyonatremia common in first 3 months
What is Pregabalin used for
Neuropathic pain
Diabetic peripheral neuropathy
what drugs are used for broad spectrum (all seizure types: generalized from onset and partial onset seizures)
Lamotrigine
Levetiracetam
topiramate
Valproate
what drugs are used for narrow spectrum ( simple partial, complex partial, and secondarily generalized seizures)
Carbamazepine
oxycarbazepine
phenobarbital
phenytoin
what drugs are used for absence seizure
Ethosuximide
how do anticonvulsants impact contraceptive
hepatic metabolism
plasma protein binding
- unplanned pregnancy, birth defects
what is the drug interaction of Lamotrigine
metabolism induced by phenytoin, carbamazepine,
inhibited by valproic acid
if an epileptic gets pregnant what happens to the frequency of epilipsy
increases
