Antiseizure Drugs

Question 1

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.

Answer 1

epilepsy

Question 2

___ 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

Answer 2

seizures

Question 3

50% of all seizure cases are considered to be ___

Answer 3

idiopathic (of unknown cause)

the remainder are secondary to brain trauma, brain anoxia (absence of O2), infection, or cerebrovascular disorders (CVA)

Question 4

seizures that are not associated with epilepsy could result from what?

Answer 4

fever, stress, hypoglycemia, electrolyte imbalances (hyponatremia), metabolic imbalance (acidosis or alkalosis), and alcohol or drug use disorders

Question 5

antiseizure drugs work in one of three ways…

Answer 5

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

Question 6

inhibit sodium influx, stabilize cell membranes, reduce repetitive neuronal firing, and limit seizures

Answer 6

hydantoins (phenytoin)

teratogenic effect on the fetus (no pregnancy)

less toxic effects, little sedation, cheap, long half life BID PO and IV

Question 7

narrow therapeutic range of phenytoin (dilantin)

Answer 7

10-20 mcg/mL

Question 8

interventions when giving phenytoin

Answer 8

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

Question 9

adverse reactions/side effects and teaching to phenytoin

Answer 9

gingival hyperplasia, urine pink/brown (hydrate), thrombocytopenia, hyperglycemia (inhibits insulin release, monitor diabetics close), some neuro issues, take with meals to decrease GI upset

Question 10

drug interactions to phenytoin

Answer 10

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)

Question 11

seizures that involve both hemispheres of the brain

Answer 11

generalized seizure

Question 12

the most common form of seizure also called grand mal

Answer 12

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

Question 13

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

Answer 13

absense seizures

Question 14

complex symptoms include automatisms (repetitive behavior), behavioral changes, and motor seizures

Answer 14

psychomotor

Question 15

do not ___ without knowing how phenytoin will affect you

Answer 15

drive

Question 16

a long-acting barbiturate, prescribed for tonic-clonic, partial, and myoclonic seizures and status epilepticus

Answer 16

phenobarbital

can build tolerance to drug and has a long half life (dose once/day)

Question 17

enhance the activity of GABA (inhibitory neurotransmitter) less pronounced side effects than phenytoin

Answer 17

barbiturates

Question 18

therapeutic range of phenobarbital

Answer 18

15-40 mcg/mL

Question 19

act by decreasing calcium influx through the T-type calcium channels

used for absence seizures

Answer 19

succinimides

ethosuximide

Question 20

therapeutic range of ethosuximide

Answer 20

40-100 mcg/mL

Question 21

labs to watch for when on ethosuximide

Answer 21

CBC (blood dyscrasias), LFTs, and renal function

Question 22

benzodiazepines that have antiseizure effects

Answer 22

clonazepam, clorazepate, lorazepam, diazepam

tolerance may occur dose TID

Question 23

which benzo is usually used for status epilepticus

Answer 23

diazepam (admin IV, max dose 30mg)

phenytoin and other seizure drugs administered following

Question 24

an iminostilbene used to control tonic-clonic and partial seizures

Answer 24

carbamazepine

also used for psychiatric disorders and trigeminal neuralgia

Question 25

therapeutic range of carbamazepine

Answer 25

4-12 mcg/mL

potentially toxic with grapefruit juice and can cause fetal abnormalities

Question 26

prescribed for tonic-clonic, absence, and partial seizures

caution when giving this drug to young children and pts with liver disorders

Answer 26

valproic acid

50-100 mcg/mL

do not take when pregnant

Question 27

__ of females with a seizure disorder are at greater risk for an increase in seizures during pregnancy

Answer 27

1/3

Question 28

many antiseizure drugs have ___ properties that increase the risk for fetal malformations

Answer 28

teratogenic

**valproic acid is known

Question 29

antiseizure drugs also tend to act as inhibitors of ___ , contributing to hemorrhage in infants shortly after birth

Answer 29

vit K

pregnant women take PO vit K 7-10 days before birth or vit K is administered to infant shortly after birth

Question 30

antiseizure drugs also increase the loss of ____ in pregnant women

Answer 30

folic acid (folate)

**take daily folate supplements

Question 31

seizures associated with fever usually occur in children between ____ and ___

Answer 31

3 months and 5 years of age

epilepsy develops in 2.5% of children who have had 1 or more febrile seizures

Question 32

prophylactic antiseizure drugs for febrile seizures that are indicated for high risk pts

Answer 32

phenobarbital or diazepam

Question 33

a continuous seizure state and is considered a medical emergency (lack of O2 to brain)

Answer 33

status epilepticus

Question 34

pharm agents for status epilepticus

Answer 34

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