Anticonvulsants
Epilepsy
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Seizure disorder
o Abnormal electric discharges from cerebral neurons
Characterized by two or more seizures
o Loss of consciousness
o Convulsive movements
Unknown cause
o Epileptic seizures often are symptoms of an underlying disorder
o Secondary to trauma, anoxia (absence of oxygen), infection, stroke
o Isolated seizures due to fever, electrolyte, or acid base balance
International classification of seizures (See Table 19.1 in book)
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Generalized
o Tonic clonic (grand mal)
 Most common
 Generalized alternating muscle spasms and jerkiness
o Absence (petit mal)
 Brief loss of consciousness (10 seconds or less)
 Usually occurs in children
Partial
o Psychomotor
 Repetitive behavior
 Chewing or swallowing motions
 Behavioral changes
 Motor seizures
Anticonvulsants/Antiepileptic Drugs (AEDS)
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Action – Suppress abnormal neuron firing – They DO NOT eliminate the cause
Suppress sodium influx
o Phenytoin (Dilantin), fosphenytoin, carbamazepine, oxcarbazepine, valproic acid,
topiramate
o Suppress calcium influx
 Valproic acid (Depakane)
o Enhance action of GABA
 Barbiturates, benzodiazepines
o Promote GABA release
 Gabapentin
Choice of AED
o Dependent on seizure type and characteristics
o Highly individualized and dependent on many factors
 Patient medical history
 Type of seizure
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 Characteristics and length of seizure
 Results of electroencephalogram (EEG)
 Presence of comorbid conditions
Dose of AED Treatment
 Begins at lowest effective dose
 Increased as necessary to prevent adverse drug effects.
 Serum drug levels may be obtained to determine drug efficacy
 Drug discontinuation or reductions must be extended over 6 to 12 weeks.
 Effective management may be obtained by a single AED
 However if seizure activity continues the initial drug is incrementally
discontinued and replaced by a different class.
Hydantoins: Phenytoin (Dilantin)
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Method of action
o Reduces motor cortex activity by altering Na ion transport
o Stabilizes against hyperexcitability that results from excessive stimulation or
environmental changes
o Prevent Tonic-clonic and Partial seizures and Status Epilepticus
o Therapeutic serum level 10 – 20 mcg/mL
Contraindications
o Pregnancy (teratogenic)
o Hypersensitivity
o Heart block, bradycardia (Since drug alters Na ion transport)
Caution
o Hyponatremia, hypotension, hypoglycemia
o Suicidal ideation, alcoholism
o Myasthenia gravis, thyroid disease, diabetes mellitus
o Renal and hepatic impairment
Side effects
o Headache
o Confusion, dizziness, drowsiness, ataxia (impaired balance or coordination, tremor.
o Insomnia, fatigue, diplopia, nystagmus
o Rash, gingival hyperplasia, anorexia, nausea, vomiting
o May cause harmless red/brown discoloration of urine
Adverse Reactions
o Leukopenia, hepatic impairment, depression, hyperglycemia (because of inhibition of
insulin)
o Bradycardia, peripheral neuropathy, purple glove syndrome
o Life threatening
 Aplastic anemia, thrombocytopenia, agranulocytosis
 Steven johnson syndrome
 Hypotension, ventricular fibrillation, suicidal ideation.
Drug interactions
o Highly protein bound – compete with many drugs
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Increased risk of bleeding: anticoagulants and aspirin
Antacids/Calcium decrease absorption
Antipsychotics and certain herbs can lower seizure threshold (Makes medication harder
to dose)
o Seizure Threshold – Level at which a seizure may be induced
Nursing Process
o Assessment
 Current meds/herbs/OTC
 Look for possible drug interactions
 Assess patients knowledge of therapy
 Hx of insomnia or anxiety?
 Check urinary output >1500 ml/day
 Renal and Liver function
o Nursing diagnosis
 Risk of injurt r/t decreased coordination
 Impaired oral mucous membranes r/t gingival hyperplasia
 Imbalanced nutrition: less r/t decreased appetite
 Risk for falls r/t dizziness
o Planning
 Patient will be free of seizures
 Patient will adhere to therapy
 Side effects will be minimal
o Nursing Interventions
 Monitor serum drug level (10-20 mcg/mL)
 Ensure pt is received adequate nutrition due to appetite loss
 Safety
 Fall precautions
 Seizure Precautions (padding, suction, O2
 Teaching
 Patients using oral contraceptives to use additional contraception.
 Discuss contemplating pregnancy with provider.
 Encourage patient to wear medical alert identification
 Warm patient of harmless pinkish red or brown urine
 Take drug at same time everyday
 Frequent oral and dental check ups
 Not to discontinue abruptly
 Report sore throat, bruising, nosebleeds
 Med should be taken with food
 Diabetic must monitor glucose levels
 Avoid certain herbs, alcohol, and other CNS depression
 Do not perform hazardous activities when initiating.
o Evaluation
 Effectiveness of controlling seizures?
 Serum phenytoin levels maintained?
Barbiturates
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Mechanism of Action
o Decreases neuronal excitability by increasing fux of chloride ions into the neuron
Indications
o Partial seizures, Tonic-Clonic seizures
o Acute episodes of Status Epilepticus Seizures
Therapeutic serum range: 20 to 40 mcg/mL
Risks
o Sedation and patient tolerance to drug
Discontinue gradually to avoid the recurrence of seizures.
Succinimides: ethosuximide (Zarontin)
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Mechanism of Action
o Decreasing calcium influx through T-type calcium channels
o Depresses motor cortex
o Increases CNS threshold to convulsive stimuli
Indications
o Absence seizures
o May be used in combination with other AEDs
Adverse effects
o Bloody dyscrasia, renal/liver impairment, systemic lupus erythematosus.
Benzodiazepines
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Clonazepam (Klonopin)
o Indication
 Effective in controlling Absence and Myoclonic Seizures
o Dosage
 Tolerance may occur 6 months after drug therapy starts
 Dosage must be adjusted
Diazepam (Valium)
o Indications
 Primarily prescribed for treating Acute Status Epilepticus
o Administration
 Must be administered IV to achieve desired response
 Short-term effect
 Other AEDs need to be given during or immediately after
 Administer slowly: Avoids Respiratory depression and hypotension
Chlorazepate
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Benzodiazepine used to treat anxiety
Iminostilbenes: Carbamazepine (Tegretol)
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Mechanism of action
o Unknown appears to exert its anticonvulsant properties by reducing the polysynaptic
response and blocking post tetanic potentiation
Indications
o Tonic-Clonic and Partial Seizures and a combination of these seizures
o Psychiatric disorders, trigeminal neuralgia, and alcohol withdrawal
o Effective in treating refractory seizure disorders that have not responded to other
anticonvulsant therapies.
o The therapeutic level is 5 to 12 mcg/mL.
Interactions
o May occur when taken with grapefruit juice, causing possible toxicity.
Valproate: Valproic acid (Depakote)
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Indication
o Used to treat Absence, Grand Mal, and Mixed types of seizures.
Safety and efficacy
o Has not been established for children younger than 2 years of age
o Caution in patients with liver disorders
 Hepatotoxicity is one of the possible adverse reactions
 Liver enzymes should be monitored
Therapeutic serum range
o 50 to 150 mcg/mL
Anticonvulsants and Pregnancy
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Seizure episodes increase 25% in women with epilepsy
Hypoxia that may occur during seizures
o Places both the pregnant patient and the fetus at risk.
Tend to act as inhibitors of vitamin K
o Contributing to hemorrhage in infants shortly after birth
Increase the loss of folate (folic acid) in pregnant patients
Anticonvulsants and Febrile Seizures
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Associated with fever usually occur 3 months – 5 years
Epilepsy develops in ~2.5% who have had febrile seizures.
Prophylactic anticonvulsant treatment such as phenobarbital or diazepam may be indicated for
high risk patients.
Anticonvulsants and Status Epilepticus
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First Line, either
o Diazepam (Valium)
o Lorazepam (Ativan)+Phenytoin (Dilantin)
Continued Seizures, either
o Midazolam (Versed)
o Propofol (Diprivan)