Anti-Epileptics Flashcards
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what is epilepsy
chronic condition of the brain characterized by recurrent seizures
what is a seizure
a single occurence caused by abnormal neuronal disharge in one part of or the entire brain
causes of epilepsy
- increased activity of voltage-gated ion channels such as Na, K and Ca
- increased excitatory glutmate transmission
- decreased inhibitory GABA transmission
target of anti-convulsants
- inhibit Na channels by prolonged inactivation
- inhibit of Ca currents in T-type Ca channels
- increased gaba transmission
- decreased glutamate transmission
inhibtion of ca currents in t-type ca channels is used to treat
absence seizures
inhibition of na channels is used to treat
focal and generalized seizures except absence seizures
classification of anti-epileptics
aliphatic carboxylic acid
1. valproic acid
newer drugs
1. lamatrogine
2. topiramte
benzodizapenes
1. diazepam
2. clonazepam
iminostilbenes
1. carbamazepene
succinimides
1. ethosoxumide
barbiturates
1. phenobarbitone
hydantoins
1. phenytoin
2. fosphenytoin
Na channel inhibitors
- phenytoin
- valproic acid
- carbamazepine
- lamotrigine
- topiramate
drug of first choice for treatment of focal and generalized seizures
phenytoin
phenytoin not useful in the treatment of
- absence seizures
- infant spasms
drug interactions of phenytoin
phenylbutazone and sulfonamides displace phenyotin
drug of choice in the treatment of status epilepticus
IV fosphenytoin
drug of choice for IV or IM adminitration
fosphenytoin
is fosphenytoin or phenytoin more water soluble
- fosphenytoin more water soluble so given IV
- phenytoin less water soluble so given orally
adverse effects of phenytoin
PHENYTOIN
- purple glove syndrome (when IV)
- hirsutism, more and coarser facial hair
- enlarged gums (gingival hyperplasia)
- nystahmus
- yellowing of skin
- teraogeniciy ie fetal hydantoin syndrome
- osteoporosis and osteomalacia
- interference of vit b12 absorption, causing macrocytic anemina
- neuropathies
fetal hyantoin syndrome
- growth retardation
- microcephaly
- facial abnormalities such as cleft palate
fetal hydantoin syndrome caused by
epioxide metabolite of phenytoin
phenytoin causes osteoporosis due to
inhibtion of iron absorption
phenytoin causes macrocytic anemia due to
impaired vit b12 absorption
at high concentrations phenyotin exhibits what order of kinetics
zero order
carbamazepine is the drug of choice for
complex partial and generalized seizures
clinical uses of carbamazepine
- complex seizures
- trigemial neuralgia
- bipolar disorder
MOA of carbamazepine
Na channel blocker
contraindications of carbamazepine
- absence or myoclonic seizures
- apalastic anermia/agranulocytosis
- rash
MOA of Lamotrigine
Na channel blocker
adverse effects of carbamazepine
PATCH
- Potentiates ADH action - water retention and hyponatremia
- Aplastic anemia/agranulocytosis
- Teratogenic
- CNS effects (diplopia, ataxia)
- Hepatic enzyme elevation
clinical uses of lamotrigine
- simple and complex seizures
- ABSENCE SEIZURES
- Lennox-Gastaut Syndrome
MOA of valproic acid
broad spectrum
- Na channel blocker
- GABA agonist
- blocker of t type Ca channels
contraindication of valproic acid
liver disease
adverse effects of VA
- NTDs
- PCOS
- weight gain
- bone loss
first line of treatment for absence seziures
valproic acid
uses of VA
- absence seizures
- myoclonic
- atonic
- simple and complex seizures
- mixed seizures
- when type of seizure cannot be detected
- photosensitive epilepsy
- juvenile myoclonic epilepsy
GABA agonists
- Barbiturates
- Benzodiazapenes
second choice for treatment of simple focal or generalized seizures
phenobarbital
contraindications of phenobarbital
absence seizures
MOA of phenobarbital
increases duration of opening of GABA channels
MOA of benzodiazepines
increase frequency of GABA channels opening
examples of benzodiazepines
- diazepam
- lorazepam
- clonazepam
which benzodiazepine is used in the treatment of most seizures
clonazepam
contraindications of benzodiazepines
- (diazepam) children under 9 years
- narrow angle glaucome
adverse effects of bzd
- hypotonia
- dysarthria
dysarthria is a common side effect of which anti-epileptic
benzodiazepines
which antiepileptic is contraindicated in narrow angle glaucoma
benzodiazepines
ca channel blockers
- ethosoxumide
- valproic acid
first line therapy for absence seizures
ethosuxumide
first line treatment for febrile seizures
diazepam
treatment of status epilepticus
- IV diazepam
- IV lorazepam
- IV fosphenytoin
- IV phenobarbitone