N160
Chapter 14
Antiepileptic Drugs
1. Overview
a. Epilepsy
i. Seizures are categorized as abnormal electrical discharges from cerebral
neurons
ii. Convulsions are involuntary contractions of voluntary muscles in the body
1. Can be identified as abnormal motor function, loss of
consciousness and altered sensory awareness
iii. Epilepsy is considered chronic seizures
iv. Status epilepticus are multiple seizures occurring no recovery in between
lasting a minimum of 5 minutes  this is a medical emergency
1. During status epilepticus the patient is not perfusing or receiving
oxygen to their brain  medical emergency
v. 75% of seizures are considered idiopathic (unknown reasons)
vi. Diagnosed by EEG, CT, and MRI
b. Epilepsy, a chronic, lifelong disorder with majority of 1st seizure before 20
c. Seizures not associated with epilepsy can result from
i. Fever
ii. Alcohol/drugs
iii. Hypoglycemia
iv. Electrolyte imbalance
v. Metabolic imbalance
vi. *When conditions are treated seizures cease
d. Emergency management
i. Safety (Do not insert anything into patient’s mouth)
1. Remove anything around the patient that can cause injury
2. Document the time seizure started, and when the seizure ended
3. Document characteristics of seizure to help identify type
4. IV Ativan given first or IV Midazolam (Versed)
e. You do not need to memorize each type of seizure
2. Antiepileptic Drugs
a. Also known as AED’s and anticonvulsants
b. Used to stabilize nerve cell membranes and abnormal electric impulses in cerebral
cortex
c. Prevent seizures, but do not eliminate cause or provide a cure
d. Classified as CNS depressants
e. With use of antiseizure drugs, 70% of seizures are controlled
f. May discontinue medication if seizure free for 3-5 years
g. Must taper slowly to reduce rebound seizures
h. Mechanism of Action and Drug Effects
i. Through movement of sodium, potassium, calcium and magnesium ions
 stabilization and less excitability of cell membrane
ii. Work in numerous mechanisms;
1. Increase threshold of activity in the motor cortex (making it more
difficult for a nerve to be excited or reduce nerve’s response to
incoming electrical or chemical stimulation)
2. Limit the spread of a seizure discharge from origin by suppressing
transmission of impulses from one nerve to the next
3. Decreasing the speed of nerve impulse conduction with a neuron
iii. Some of the drugs enhance effects of gamma aminobutyric acid (GABA)
1. Low levels of GABA are associated with seizures  many
antiepileptic drugs increase levels of GABA to prevent seizures
from occurring.
i. Contraindications
i. Allergy and pregnancy
j. Adverse Effects
i. Can cause of lot of unpleasant effects  this can also be problematic with
compliance
ii. Most common effects are GI related (nausea, vomiting and diarrhea)
iii. Black box warning initiated in 2008 for antiepileptic drugs for suicidal
behaviors and thoughts
k. Interactions
i. Numerous interactions including altered CYP450 metabolism
ii. Reduced efficacy of birth control  need to use alternative source of birth
control
l. Nursing Considerations
i. Must check serum levels if drug has narrow therapeutic range
ii. Assess potential pregnancy status for female patients
iii. Assess history of preexisting hepatic or renal dysfunction
iv. Assess mental status for suicidal ideation
v. Assess patient’s nutritional status before, and during treatment due to
many GI symptoms (nausea, diarrhea and vomiting)
vi. Ensure patient is under seizure precautions (safe environment,
m. Patient Education
i. Instruct the patient not to abruptly discontinue therapy  rebound seizures
can occur
ii. Advise patient and family to contact provider immediately should any
thoughts of suicide occur
iii. Advise female patients to contact health provider before trying to get
pregnant
n. Drug Profiles
i. Barbiturates
1. Phenobarbital
a. Causes sedation  need to educate patient of when to take
the dose, and not to drive/operate heavy machinery
b. Therapeutic serum levels: 10-40 mcg/mL
c. Enzyme inducer (increases metabolism of other drugs)
meaning it should be taken alone
Route
Onset
Peak
Half-Life
Duration
PO
60 min
2-4 hr
50-120 hr
6-12 hr
IV
5 min
30 min
50-120 hr
6-12 hr
ii. Hydantoins
1. Phenytoin
a. Prototype and first-line drug
b. Contraindicated in patients with bradycardia
c. Most common adverse effect is gingival hyperplasia –
must monitor dental health closely
d. Therapeutic serum levels: 10-20 mcg/mL
i. Toxicity can cause: nystagmus, ataxia, dysarthria
and encephalopathy
e. Enzyme inducer (increases metabolism of other drugs)
meaning it should be taken alone
f. Need to monitor albumin levels closely  especially in
malnourished or chronic renal failure patients  low
albumin = more free unbound drug in blood
g. Extremely irritating to the veins  risk of extravasation
h. Teratogenic – cannot take during pregnancy. If planning to
have children or become pregnant  need to switch AED’s
Route
Onset
Peak
Half-Life
Duration
PO
Unknown
12 hr
7-42 hr
12-36 hr
IV
1-2 hr
2-3 hr
10-12 hr
12-24 hr
*The following drugs do not need to be memorized except you should
know gabapentin (Neurontin) and levetiracetam (Keppra)
iii. Iminostilbenes
1. carbamazepine (Tegretol)
a. Chemically related to tricyclic antidepressants
b. Associated with autoinduction of hepatic enzymes  over
time drug stimulates production of enzymes enhancing it’s
own metabolism leading to lower than expected drug
concentrations
2. oxcarbazepine (Trileptal)
iv. Succinimides
1. ethosuximide (Zarontin)
v. Miscellaneous Drugs
1. gabapentin (Neurontin)
a. Chemical analogue of GABA
b. Also commonly used for neuropathic pain
c. High chance of mis-use
2. lamotrigine (Lamictal)
a. High risk of causing Stevens-Johnson syndrome
3. levetiracetam (Keppra)
a. Can cause CNS depression and fatigue
b. Commonly used in the acute-care setting as prophylaxis for
head trauma
4. pregalbin (Lyrica)
a. Controlled substance due to the risk of mis-use
5. topiramate (Topamax)
6. valproic acid