Antiseizure Drugs Flashcards
a seizure disorder that results from abnormal electric discharges from the cerebral neurons characterized by a loss or disturbance of consciousness and usually involuntary, uncontrolled movements.
epilepsy
___ occur when there is a disruption in the electrical functioning of the brain due to an imbalance in the excitation and inhibition of electrical impulses
seizures
50% of all seizure cases are considered to be ___
idiopathic (of unknown cause)
the remainder are secondary to brain trauma, brain anoxia (absence of O2), infection, or cerebrovascular disorders (CVA)
seizures that are not associated with epilepsy could result from what?
fever, stress, hypoglycemia, electrolyte imbalances (hyponatremia), metabolic imbalance (acidosis or alkalosis), and alcohol or drug use disorders
antiseizure drugs work in one of three ways…
1) by suppressing sodium influx through the drug binding to the sodium channel when it is inactivated, which prolongs the channel inactivation and thereby prevents neuron firing
2) by suppressing the calcium influx, which prevents the electric current generated by calcium ions to the T-type calcium channel
3) by increasing the action of GABA, which inhibits neurotransmitters throughout the brain
inhibit sodium influx, stabilize cell membranes, reduce repetitive neuronal firing, and limit seizures
hydantoins (phenytoin)
teratogenic effect on the fetus (no pregnancy)
less toxic effects, little sedation, cheap, long half life BID PO and IV
narrow therapeutic range of phenytoin (dilantin)
10-20 mcg/mL
interventions when giving phenytoin
give through central or PICC line, dilute with NS only
watch for local irritation at the injection site and sloughing. IV should always be flushed with saline before and after each dose to reduce venous irritation
adverse reactions/side effects and teaching to phenytoin
gingival hyperplasia, urine pink/brown (hydrate), thrombocytopenia, hyperglycemia (inhibits insulin release, monitor diabetics close), some neuro issues, take with meals to decrease GI upset
drug interactions to phenytoin
increase anticoag and aspirin activity, barbiturates increase phenytoin activity, decrease BC pill (use other method of contraception)
antipsychotics and certain herbs can lower the seizure threshold (the lvl at which seizure may be induced, and they increase seizure activity)
seizures that involve both hemispheres of the brain
generalized seizure
the most common form of seizure also called grand mal
tonic-clonic
tonic phase = skeletal muscles contract or tighten in a spasm that lasts 3-5 seconds
clonic phase = dysrhythmic muscular contraction occurs with a jerkiness of legs and arms that lasts 2-4 min
seizure with a brief loss of consciousness lasts less than 10 secs with fewer than 3 spike waves on the EEG
usually occurs in children; petit mal
absense seizures
complex symptoms include automatisms (repetitive behavior), behavioral changes, and motor seizures
psychomotor
do not ___ without knowing how phenytoin will affect you
drive
a long-acting barbiturate, prescribed for tonic-clonic, partial, and myoclonic seizures and status epilepticus
phenobarbital
can build tolerance to drug and has a long half life (dose once/day)
enhance the activity of GABA (inhibitory neurotransmitter) less pronounced side effects than phenytoin
barbiturates
therapeutic range of phenobarbital
15-40 mcg/mL
act by decreasing calcium influx through the T-type calcium channels
used for absence seizures
succinimides
ethosuximide
therapeutic range of ethosuximide
40-100 mcg/mL
labs to watch for when on ethosuximide
CBC (blood dyscrasias), LFTs, and renal function
benzodiazepines that have antiseizure effects
clonazepam, clorazepate, lorazepam, diazepam
tolerance may occur dose TID
which benzo is usually used for status epilepticus
diazepam (admin IV, max dose 30mg)
phenytoin and other seizure drugs administered following
an iminostilbene used to control tonic-clonic and partial seizures
carbamazepine
also used for psychiatric disorders and trigeminal neuralgia
therapeutic range of carbamazepine
4-12 mcg/mL
potentially toxic with grapefruit juice and can cause fetal abnormalities
prescribed for tonic-clonic, absence, and partial seizures
caution when giving this drug to young children and pts with liver disorders
valproic acid
50-100 mcg/mL
do not take when pregnant
__ of females with a seizure disorder are at greater risk for an increase in seizures during pregnancy
1/3
many antiseizure drugs have ___ properties that increase the risk for fetal malformations
teratogenic
**valproic acid is known
antiseizure drugs also tend to act as inhibitors of ___ , contributing to hemorrhage in infants shortly after birth
vit K
pregnant women take PO vit K 7-10 days before birth or vit K is administered to infant shortly after birth
antiseizure drugs also increase the loss of ____ in pregnant women
folic acid (folate)
**take daily folate supplements
seizures associated with fever usually occur in children between ____ and ___
3 months and 5 years of age
epilepsy develops in 2.5% of children who have had 1 or more febrile seizures
prophylactic antiseizure drugs for febrile seizures that are indicated for high risk pts
phenobarbital or diazepam
a continuous seizure state and is considered a medical emergency (lack of O2 to brain)
status epilepticus
pharm agents for status epilepticus
1) diazepam or lorazepam IV
followed by
2) phenytoin IV
For continuing seizures, midazolam or propofol and then high-dose barbiturates
administer slowly to avoid respiratory depression
