Clozapine for schizophrenia

Examples

The U.S. Food and Drug Administration (FDA) recently approved clozapine for treating suicidal behavior associated with schizophrenia, or for treating severe schizophrenia which 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 by your doctor and the Clozaril National Registry, and special monitoring is needed when clozapine is used.

How It Works

Clozapine is a second-generation antipsychotic. It is believed to affect the way brain chemicals (neurotransmitters) work.

Why It Is Used

Clozapine is used to treat the symptoms of schizophrenia. It may be used when another medicine cannot be used or has not been effective.

How Well It Works

Clozapine is an effective treatment for symptoms of schizophrenia and may reduce symptoms that have not been controlled by other medicines. It may be more effective both in the short and long term than first-generation antipsychotic medicines (such as haloperidol) for some people.¹ It has not been proven more effective than atypical (second-generation) antipsychotics, such as risperidone.

Side Effects

New warnings about serious side effects of clozapine have recently been issued. The FDA and the drug's manufacturer have strengthened warnings to include that a potentially fatal heart problem (myocarditis) may occur when a person takes clozapine. Also, there is evidence that taking clozapine may increase the risk of developing insulin resistance, diabetes, and hyperglycemia (high blood sugar).² So even though clozapine is effective in treating the symptoms of schizophrenia, discuss the possibility of these serious side effects with your doctor before taking this medicine.

The most common side effects of clozapine are:

• Sluggishness or sleepiness.
• Weight gain.
• Increased saliva production.

Other side effects include:

• Increased heartbeat.
• Lowered blood pressure.
• Fever.
• Seizures, but usually in those taking high doses.

A rare but potentially deadly side effect is agranulocytosis, a condition that causes reduced production of white blood cells. Weekly blood cell counts are required during the first 6 months of treatment with this medicine, with subsequent monitoring every 2 weeks.^{3, 1} Closely monitoring white blood cell counts can lower your chances of having this side effect.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Those who have seizures, heart or blood vessel problems, or liver or kidney conditions 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 older antipsychotic medicines, people with schizophrenia may be more likely to take it regularly.

Clozapine costs more than first-generation antipsychotic medicines. Many companies who manufacture medicines have programs for people who cannot afford the high cost of medicine. Ask your health professional whether you qualify to receive free medicine.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.

References

Citations

1. Nadeem Z, et al. (2003). Schizophrenia. Clinical Evidence (9): 1103-1133.

2. Koller E, et al. (2001). Clozapine-associated diabetes. American Journal of Medicine, 111(9): 716-723.

3. Goff DC, et al. (2001). Schizophrenia. Medical Clinics of North America, 85(3): 663-689.

Credits