C H A P T E R 2 3
Antiseizure agents
365
DRUGS FOR TREATING PARTIAL SEIZURES
Partial seizures may be simple (involving only a single
muscle or reaction) or complex (involving a series of reac
tions or emotional changes). Drugs used in the treatment
of partial seizures include carbamazepine (
Tegretol
,
Teril
), gabapentin (
Neurontin
), lacosamide (
Vimpat
),
lamotrigine (
Lamictal
), levetiracetam (
Keppra
), oxcar
bazepine (
Trileptal
), pregabalin (
Lyrica
), tiagabine
(
Gabitril
) and topiramate (
Topamax
) (see Table 23.3).
Some of the drugs used to treat generalised seizures have
also been found to be useful in treating partial seizures
(see Table 23.1).
Therapeutic actions and indications
The drugs used to control partial seizures stabilise
nerve membranes in either of two ways—directly, by
altering sodium and calcium channels, or indirectly,
by increasing the activity of GABA, an inhibitory neuro
transmitter, and thereby decreasing excessive activity
(see Figure 23.2). Carbamazepine and oxcarbazepine
are used as monotherapy, and the remaining drugs are
used as adjunctive therapy (see Table 23.3 for usual
indications for each agent). Each of the drugs used for
treating partial seizures has a slightly different mech
anism of action.
Carbamazepine is chemically related to the tricyclic
antidepressants. It has the ability to inhibit polysynaptic
responses and to block sodium channels to prevent the
formation of repetitive action potentials in the abnormal
focus.
Gabapentin (
Neurontin
) inhibits polysynaptic
responses and blocks stimulus increases in certain situ
ations. However, the mechanism by which gabapentin
exerts its anticonvulsant action is unknown. Gabapen
tin is structurally related to the neurotransmitter GABA
(gamma-aminobutyric acid) but its mechanism of action
is different from that of several other medications that
interact with GABA synapses including valproate,
Monitor for adverse effects: CNS effects (multiple); bone
marrow suppression; rash, skin changes; GI effects—
nausea, anorexia; arrhythmias.
Monitor for drug–drug interactions: increased depression
with CNS depressants, alcohol; drugs as listed.
Evaluate effectiveness of teaching program.
Evaluate effectiveness of comfort/safety measures.
Teaching for J.M.
• The drugs that are being evaluated for you are called
antiepileptic agents. They are used to stabilise abnormal
cells in the brain that have been firing excessively and
causing seizures.
• The timing of these doses is very important. To be
effective, this drug must be taken regularly.
• Do not stop taking this drug suddenly. If for any reason
you are unable to continue taking the drug, notify your
healthcare provider at once. This drug must be slowly
withdrawn when its use is discontinued.
• Common effects of these drugs include:
•
Fatigue, weakness, and drowsiness:
Try to space activities
evenly throughout the day and allow rest periods to
avoid these effects. Take safety precautions and avoid
driving or operating dangerous machinery if these
conditions occur.
•
Headaches and difficulty sleeping:
These usually disappear
as your body adjusts to the drug. If they persist
and become too uncomfortable, consult with your
healthcare provider.
•
Gastrointestinal upset, loss of appetite, and diarrhoea or
constipation:
Taking the drug with food or eating small,
frequent meals may help alleviate this problem.
• Report any of the following conditions to your
healthcare provider:
skin rash, severe nausea and vomiting,
impaired coordination, yellowing of the eyes or skin, fever,
sore throat, personality changes, and unusual bleeding or
bruising
.
• It is advisable to wear or carry a Medic-Alert warning so
that any person who takes care of you in an emergency
will know that you are taking this drug.
• Tell any doctor, nurse or other healthcare provider
involved in your care that you are taking this drug.
• Keep this drug and all medications out of the reach of
children.
• Do not take any other drug, including over-the-counter
medications and alcohol, without consulting with your
healthcare provider. Many of these preparations interact
with the drug and could cause adverse effects.
• Report and record any seizure activity that you have while
you are taking this drug.
• Take this drug exactly as prescribed. Regular medical
follow-up, which may include blood tests, will be
necessary to evaluate the effects of this drug on your
body.
Safe medication administration
Name confusion has been reported between Keppra
(levetiracetam) and Kaletra (lopinavir/ritonavir), an HIV antiviral
combination drug. Both drugs come in a liquid form, and
confusion has been reported in the administration of the two
drugs, causing serious adverse effects. Use extreme caution
when administering these drugs.
