occur in only 1% of terminally ill patients.
Hyponatremia (very rare)
are rare with brain metastases. Routine prophylaxis with anti- convulsants is unnecessary, and need only be started after the
above options the diazepam enema is the simplest
treatment. The effect is often almost instantaneous. It can be
repeated after 5 minutes if necessary, and it is safe to give
4 enemas over a period of 30 minutes. If convulsions recur
later that day 4 more enemas can be given over a period of 30
minutes. (Diazepam enemas are not available commercially in
the United States, but some enterprising pharmacists prepare
them for use in hospice and palliative care.) IV diazepam 10mg
can be used instead of the diazepam enema.
In the rare
case where convulsions are not controlled by diazepam, IM
phenobarbital 200mg can be given (although it is absorbed
slowly). Alternatively, paraldehyde IM or rectally is
virtually always effective.
method is to use water-soluble phenobarbital in a separate
continuous subcutaneous infusion (400mg to 600mg per day). It
cannot be mixed in the same infusion with other drugs.
Preventing seizures – If a patient requires regular
anticonvulsant medication to prevent seizures, oral phenytoin
300mg at bedtime is usually the drug of first choice.
recur, ensure that plasma levels are in the therapeutic range
(10mg/L to 20mg/L) [40µmol/L to 80µmol/L]. If low,
increase phenytoin gradually by 50mg per day, because small
increases in dose can cause large increases in plasma levels (saturable
metabolism). Levels above 25mg/L [100µmo/L] can cause
drowsiness and ataxia. Avoid combinations of anti-convulsants
whenever possible. Drug interactions occur.
phenytoin is ineffective or not tolerated, change to valproic
acid 200mg 3 times a day. If seizures recur, increase the dose
to a maximum of 400mg 4 times a day. It can cause nausea and
is best taken after food. Plasma levels do not accurately
reflect activity with valproic acid, so routine monitoring of
plasma levels is not helpful.
Carbamazepine and valproic acid both lower effective phenytoin
levels. Phenytoin potentiates diazepam.
seizures (twitching of the corner of the mouth, or in one
finger, or in one arm or leg) are distressing because the
patient is often still conscious. They can develop into a
generalized seizure. Focal seizures are best controlled by
diazepam (enema or IV). The best drug for prophylaxis is
carbamazepine, starting with 100mg to 200mg 2 times a day, and
increasing gradually up to 400mg 4 times a day if necessary.
Drowsiness and dizziness can occur. Plasma levels should be
monitored initially (optimum levels are 4mg/L to 12mg/L) [17µmol/L
acid is effective in generalized and focal seizures. It is
best reserved for cases where other drugs are ineffective or
cannot be tolerated. Start with oral valproic acid 200mg 3
times a day (after food to avoid gastric irritation and
nausea), increasing by steps to 300mg to 600mg 4 times a day
if convulsions are not controlled. Plasma levels do not
correlate with effect and are not helpful. Side effects
include drowsiness, altered lung function, reduced platelets,
increased appetite, edema and (rarely) jaundice.
patient cannot swallow prophylactic anti-convulsants because
of dysphagia, vomiting or unconsciousness, give IM
phenobarbital 100mg 2 times a day, or watersoluble
phenobarbital 200mg per day in a separate continuous
are very frightening for the family (and for the patient with
focal seizures) and explanation is essential.
Common worries include:
cause brain damage?
shorten the life span?
patient die during a seizure?
Seizures should be controlled even in an unconscious patient
for the sake of the family.
The author and publisher have taken
precautions to ensure that the information in this book is
error-free. However, readers must be guided by their own
personal and professional standards of good practice in
evaluating and applying recommendations made herein. The
contents of this book represent the views and experience of
the author, and not necessarily those of the publisher.