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Clozapine
is an atypical antipsychotic medication for patients with
treatment-resistant schizophrenia. Approved by the FDA for
general use in the U.S. in 1990, the drug is used for patients
with schizophrenia and other mental disorders who have not
responded well to standard antipsychotic drugs or who have
had intolerable side effects to them. Novartis manufactures
and markets clozapine under the brand name Clozaril. Generic
forms of clozapine are marketed by Zenith Goldline and Mylan
Pharmaceuticals.
What
is new about Clozapine?
Clozapine has unique benefits and unique risks. The benefits
make it a source of hope for the substantial number of patients
with schizophrenia who have not responded well to traditional
antipsychotic medications. Although Clozapine use has certain
risks, a careful monitoring system has been designed to manage
and minimize them.
What
are the benefits of Clozapine?
Unique effectiveness: In responsive patients, Clozapine adds
another alternative to the traditional antipsychotic medications
in treating the positive symptoms of schizophrenia such as
hallucinations, delusions, bizarre behavior and hostility.
It also effectively treats the negative symptoms-
withdrawal, blunted emotions, lack of motivation, and inability
to experience pleasure or enjoyment. It is the negative symptoms
that seem to respond better to Clozapine than to the traditional
antipsychotics.
Lack of usual side
effects: Clozapine has virtually no incidence of the muscle
spasms, cramps, and posturing movements common to neuroleptic
(antipsychotic) drugs, and minimal incidence of the less serious
neurological side effects such as restlessness, muscle rigidity,
and tremor (extrapyramidal side effects or EPS).
Furthermore, Clozapine
does not seem to cause tardive dyskinesia (TD), a disfiguring
side effect of standard antipsychotic drugs. TD is characterized
by involuntary movements such as grimacing, sucking and smacking
of lips, and spasmodic movements of the extremities. It usually
begins after several months of treatment and may be irreversible.
There have been no confirmed cases of TD directly caused by
Clozapine alone.
Does
every patient respond to Clozapine?
Clozapine is effective for about 60 percent of those who try
it. A patient should try Clozapine for at least four to six
weeks. Some symptoms, such as hallucinations, anxiety, paranoia,
and bizarre behavior, should improve within that time; other
symptoms may take longer. Additional improvements may be noticed
over six to twelve months.
Do
the benefits of Clozapine outweigh the risks?
Clozapine poses a unique risk. Consequently, the FDA would
not have approved it unless its effectiveness was proven clearly
superior to that of current antipsychotic drugs. This was
done conclusively in a 16-center study involving over 300
severely ill patients. These patients had been ill for many
years and had failed to respond to at least three potent drugs.
In other studies
of Clozapine patients, 55 percent of previously hospitalized
patients were able to work at paying or volunteer jobs or
return to school, and re-hospitalization was reduced by 83
percent after 12 months. This improvement in psychosocial
functioning was largely due to Clozapine response.
What
is the "unique risk" associated with Clozapine?
One to two percent of patients who take Clozapine will develop
a condition called agranulocytosis, in which the white blood
cell count drops dramatically. The patient becomes extremely
vulnerable to infections and unable to fight them off. This
condition is dangerous and potentially fatal. Fortunately,
if agranulocytosis does occur, most patients can be successfully
treated by stopping Clozapine. In addition to stopping Clozapine,
hospitalization and treatment with a drug that increases white
blood cell production are available.
Isn't
agranulocytosis associated with other drugs as well?
Yes. Other medications, including other antipsychotics, also
cause agranulocytosis, but the incidence with Clozapine is
over 10 times that of other antipsychotics.
How
can the risk of agranulocytosis be minimized?
To maintain safety, the patient's white blood cell count must
be checked each week for the first six months and then every
other week after that. The results are sent to the patient's
pharmacy before the next week's supply can be picked up. If
detected early enough, the condition can be reversed by simply
withdrawing the patient from Clozapine. Hospitalization and
treatment with medication to stimulate production of white
blood cells has been done with great success.
Are
other risks associated with Clozapine?
Seizures may occur in roughly one to five percent of patients.
The higher the dose, the greater the risk of seizures. Cardiovascular
and respiratory side effects are also possible but extremely
rare. Lowered blood pressure and increased heart rate can
usually be managed by gradually increasing a patient's Clozapine
dosage from an initially low level. Some patients may notice
weight gain, drooling, and initial lethargy but can be managed
by dose titration (adjustment) or other interventions.
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