The U.S. Food and Drug Administration (FDA) approved
clozapine for treating suicidal behavior associated with schizophrenia or for
treating severe schizophrenia that has not improved with other medicines.
Its use for treating other symptoms of schizophrenia has not yet been approved in the U.S., except through special authorization.
When you use this medicine, your name goes into the Clozaril National Registry so that if you have severe side effects, you are not given the medicine again.
How It Works
Clozapine is a second-generation
antipsychotic. It is thought to affect the way brain chemicals (neurotransmitters) work.
Why It Is Used
Clozapine is used to treat the
schizophrenia if other medicines don't work or if the
person may be thinking about suicide.
How Well It Works
Clozapine may reduce symptoms of
schizophrenia that have not been controlled by other medicines.
Some warnings about serious side effects
of clozapine have been issued.
- The U.S. Food and Drug Administration (FDA)
and the drug maker have strengthened warnings to say that clozapine may cause a
possible life-threatening heart problem (myocarditis).
- Clozapine may make you more likely to develop
diabetes, and hyperglycemia (high blood
A rare but possibly life-threatening side effect is
agranulocytosis, a problem that causes your body to make fewer white blood
cells. You need weekly blood cell tests during the first 6 months of treatment
with this medicine and tests every 2 weeks after this period of time.1 This helps the doctor find this side effect early.
The most common side effects of clozapine are:
- Feeling sleepy or slow
- Having more saliva.
Other side effects include:
- A faster heartbeat.
- Lower blood
- Seizures, but
usually in those taking high doses.
See Drug Reference for a full list of side effects. (Drug
Reference is not available in all systems.)
What To Think About
Because of the side effects, talk
with your doctor about whether this medicine is right for you. If you have had
a seizure, heart or blood vessel problems, or liver or kidney problems, you
probably should not take clozapine.
It is not known whether
clozapine is safe for children, older adults, and nursing women.
Because clozapine does not have some of the bothersome side effects of
the first-generation antipsychotic medicines, people who have schizophrenia may be more likely
to take it regularly.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Durham J (2009). Schizophrenia: A review of pharmacologic and nonpharmacologic treatments. US Pharmacist, 34(11): 1-5.