anti-epileptic drugs Flashcards
what is meant by seizure?
abnormal, excessive excitation and synchronization of a population of cortical neurons
what is meant by epilepsy?
recurrent seizures unprovoked by any immediately identifiable cause
what can triggers seizure?
- photic stimuli
- sleep deprivation
- infection, fever
- trauma
- drug that decrease seizure threshold
- drug withdrawal
- alcohol withdrawal
- metabolic/ endocrine
the classification of seizure
- generalized seizure
- focal/ partial seizure
- unknown
what is generalize seizure?
originating at some point within and rapidly engaging bilaterally distributed networks
definition of focal/ partial seizure
originating in networks limited to one hemisphere
complications of partial seizure
- impaired consciousness
- ictal automatisms (automatic seizure)
- abnormal behavior
- confusion
characteristics of generalized seizure
- immediated synchronous spike and wave discharge
- involve both hemispheres
- involve reticular activating system
- immediate loss of consciousness
types of generalized seizure
- tonic
- clonic
- tonic-clonic
- myoclonic
- atonic
- absence
function of sodium channel blockers
- block the excitation of cells that are firing repetitively
- the higher the frequency of firing, the greater the block
characteristics of phenytoin (PHT)
- oral slow
- 90% protein bound
- enzyme inducer
- zero order kinetic
- steep dose-concentration relationship
- most problematic drug interactions
function of phenytoin (PHT)
- given IV
- given once daily
- can measure drug level
- DO NOT use in absence seizure
- used in PARTIAL + GENERALIZED seizures
- used in status epilepticus
side effects of phenytoin (PHT)
- cardiac and respi depress
- malabsorption
- osteoporosis
- hepatitis
- hirsutism
- gum hyperplasia
- mentation
- teratogenic
what is fosphenytoin?
- prodrug for phenytoin
- given IV
- infused 3 times faster then PHT
- used in status epilepticus
- cardiodepressant
characteristics of carbamazepine
- given PO
- Na+ channel blocker
- half life 15-30 hours
- 80% protein bound
- NO IV
- enzyme inducer
- can measure drug levels
function of carbamazepine
- treat depression
- treat neuropathic pain
- treat partial and secondary generalized seizures
- no ABSENCE and MYOCLONIC
side effects of carbamazepine
- hepatitis
- hypersensitivity
- hyponatremia
- haematologic
- skin reaction
- dysrhythmias
- dizzy, ataxia
- steven johnson syndrome
characteristics of oxcarbazepine
- Na+ channel blocker
- less induction
- oral half life 8 hours
- 40% protein binding
functions of oxcarbazepine
- used in partial seizure
- used in secondary generalized seizure
side effects of oxcarbazepine
- somnolence
- increase weight
- dizzy, ataxia
- headache
- hyponatremia
- alopecia (loss of hair)
- rash
characteristics of lamotrigine
- Na+ channel and Ca+ channel blocker
- may make myoclonic WORSE
- oral ONLY
- good in elderly
- not an inducer
- 55% protein binding
- hepatic metabolism
- dose varies
functions of lamotrigine (LTG)
- treat most seizure types
- used in depression
- neuropathic pain
side effects of lamotrigine (LTG)
- AED hypersensitivity syndrome
- rash, FUO, influenza
- drowsy, headache, irritable
- diplopia, ataxia, dizzy, tremor
- haematologic
what is GABA?
- major inhibitory neurotransmitter
- cause Cl influx
- hyperpolarisation
type of GABA A receptor
- benzodiazepine
- barbiturates
- clobazam
- clonazepam
list of GABA drugs that used in first line in treating epilepsy
- gabapentin
- pregabalin
- valproate
examples of drugs benzodiazepines
- diazepam
- clonazepam
- lorazepam
- midazolam (converted into neurosteroids)
uses of benzodiazepines
- sedation
- muscle relaxant
- anticonvulsants
- alcohol withdrawal
- given PO the best and IV if status epilepticus
characteristics of benzodiazepines
- 7 aromatic ring
- lipid soluble
- high therapeutic index
side effects of benzodiazepines
- decrease in motor skills
- ataxia, fracture
- vertigo
- excitement
- amnesia (partial/total loss of memory)
- drowsiness
main use of phenobarbitone and example of drug
- in status epilepticus through IV
- eg: primidone
side effects of phenobarbitone
- inducer
- sedation
- ataxia
- respiratory depression
- rash
- malabsorption
- anemia
characteristics of valproate
- Na+ channel blocker
- Ca+ channel blocker
- usually given PO
- half life 15 hours
- bad for preggy mother
functions of valproate
- inhibits most seizures
- increase GABA
- used in depression
- used in migraine
side effects of valproate
- hepatitis
- pancreatitis
- alopecia
- weight gain
- sedation
- ataxia
- tremor
- increase ammonia
function of gabapentin
- decrease calcium influx
- treat partial seizure
- neuropathic pain
- no interaction
side effects of gabapentin
- behaviour
- cerebellar
- rhinitis
- pancreatitis
- rash
- joints
- alopecia
function of pregabalin
- decrease calcium influx
- partial seizures
- neuropathic pain
- anxiolytic
side effects of pregabalin
- ataxia
- sleepiness
- weight gain
- sexual dysfunction
- vision problem
examples of calcium channel and what type of seizure?
- ethosuximide (ETX)
- zonisamide (ZNS)
- treat ABSENCE epilepsy
side effects of ethosuximide (ETX)
- ANV (anticipatory nausea and vomiting)
- dizziness
- sleep
- haematologic
- behavioural
characteristics of zonisamide (ZNS)
- non-inducer
- no interactions
- once daily
- 50% protein binding
- ## half life 60 hours
functions of zonisamide (ZNS)
- acts at Na+ and at T-type Ca channel
- inhibits carbonic anhydrase
- as add-on therapy for partial, myoclonic and absence seizures
side effects of zonisemide (ZNS)
- PSYCHOSIS
- TERATOGEN
- coma, somnolence
- stones
- oligohidrosis (absence of sweating)
- speech, cerebellar
5 binding sites for glutamate
- NMDA
- AMPA
- KAINATE
- glycine
- glu A subunits
postsynaptic blocker for glutamate
AMPA blocker - phenobarbitone - topiramate - lamotrigine NMDA - felbamate
functions of topiramate (TPM)
- inhibits Na and Ca ion channels
- enhance K+ current
- used for migraine
- used for partial and generalized seizures
- treat lennox gastaut
- treat obesity
- treat psychiatric disorder
side effects of topiramate (TPM)
- cognitive- verbal fluency
- dizzy, ataxia
- paresthesia
- agitation
- acidosis
- hyperthermia
- nephrolithiasis (kidney stones)
- weight loss
functions of levetiracetam (most ideal AED drug)
- first line in partial and second in generalized seizure
- alter Ca+ entry
- regulates vesicular exocytosis
- no metabolites
- half life 6-8 hours
side effects of levetiracetam
- SUICIDE
- somnolence
- dizzy, ataxia, tremor
- psychosis
- cough
- rash
- ANV
- haematological
functions of lacosamide
- enhances slow inactivation of voltage gated Na+ channels
- inhibiting neuropathic factors
- as add on therapy for treating partial seizures
side effects of lacosamide
- cerebellar
- prolongs PR interval
- headache, drowsiness
- tremor
- suicide
functions of ezogabine (EZB)
- add on treatment for partial seizures
- promotes opening of voltage K+ channels
- inhibits high frequency AP firing
side effects of ezogabine (EZB)
- urinary retention
- suicide
- ataxia, dizzy
- somnolence
- QT prolong
- blue nails and retina pigment
functions of perampanel
- adjunctive therapy for partial seizure
- highly selective and non-competitive AMPA antagonist
side effects of perampanel
- psychiatric
- behavioural
- dizziness
- somnolence
definition of status epilepticus
more than 10 mins of continuous seizure OR 2 or more recurrent seizure without recovery cause by thymine deficiency
medication for status epilepticus
- diazepam (rectal)
- midazolam
- lorazepam (IV)
- phenytoin
- propofol (IV) (local anas)
