C H A P T E R 2 3
Antiseizure agents
363
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Drugs used to treat generalised seizures include the
hydantoins, barbiturates and benzodiazepines.
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Drugs used to treat absence seizures—a particular
type of generalised seizure—include the hydantoins,
succinimides, acetazolamide, sodium valproate and
zonisamide.
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All of these drugs stabilise nerve membranes
throughout the CNS to decrease excitability and
hyperexcitability to stimulation.
■■
Adverse effects associated with these drugs reflect the
CNS depression—lethargy, somnolence, fatigue, dry
mouth, constipation and dizziness. Serious liver, bone
marrow and dermatological problems can occur with
specific drugs.
KEY POINTS
■
■
Administer the drug with food
to alleviate GI
irritation if GI upset is a problem.
■
■
Monitor for adverse effects and provide
appropriate supportive care as needed
to help the
person cope with these effects.
■
■
Monitor full blood count (FBC) before and
periodically during therapy
to detect bone marrow
suppression early and provide appropriate
interventions.
■
■
Discontinue the drug if skin rash, bone marrow
suppression or unusual depression or personality
changes occur
to prevent the development of more
serious adverse effects.
■
■
Discontinue the drug slowly, and never withdraw
the drug quickly,
because rapid withdrawal may
precipitate absence seizures.
■
■
Monitor for drug–drug interactions
to arrange to
adjust doses appropriately if any drug is added to
or withdrawn from the drug regimen.
■
■
Arrange for counselling for women of childbearing
age who are taking these drugs.
Because these
drugs have the potential to cause serious damage
to the fetus
, women should understand the risk
of birth defects and use barrier contraceptives to
avoid pregnancy.
■
■
Offer support and encouragement
to help the
person cope with the drug regimen.
■
■
Provide thorough teaching, including drug name
and prescribed dosage, as well as measures for
avoidance of adverse effects and warning signs
that may indicate possible problems
to enhance
knowledge about drug therapy and to promote
compliance
; and the need for periodic blood tests
to evaluate blood counts to reduce the risk of
infection and for drug levels to evaluate therapeutic
effectiveness and minimise the risk for toxicity
.
■
■
Suggest the wearing or carrying of a MedicAlert
bracelet
to alert emergency workers and healthcare
providers about the use of an antiepileptic drug.
Evaluation
■
■
Monitor response to the drug (decrease in
incidence or absence of seizures; serum drug
levels within the therapeutic range); evaluate for
therapeutic blood levels (40 to 100 mcg/mL) for
ethosuximide
to ensure the most appropriate dose
of the drug.
■
■
Monitor for adverse effects (CNS changes, GI
depression, urinary retention, arrhythmias, blood
pressure changes, liver toxicity, bone marrow
suppression, severe dermatological reactions).
■
■
Evaluate the effectiveness of the teaching plan
(person can give the drug name and dosage and
name possible adverse effects to watch for and
specific measures to prevent them; person is aware
of the risk of birth defects and the need to carry
information about the diagnosis and use of this
drug).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
CRITICAL THINKING SCENARIO
Antiepileptic drugs
THE SITUATION
J.M., an athletic, 18-year-old high school student, suffered
his first seizure during maths class. He seemed attentive
and alert, and then he suddenly slumped to the floor and
suffered a full tonic–clonic (grand mal) seizure. The other
students were frightened and did not know what to do.
Fortunately, the teacher was familiar with seizures and
quickly reacted to protect J.M. from hurting himself and to
explain what was happening.
J.M. was diagnosed with idiopathic generalised
epilepsy with tonic–clonic (grand mal) seizures. The
combination of phenytoin and phenobarbitone that he
began taking made him quite drowsy during the day. These
drugs were unable to control the seizures, and he suffered
three more seizures in the next month—one at school
and two at home. J.M. is now undergoing re-evaluation for
possible drug adjustment and counselling.
