Clozapine

Clozapine is a prescription medication used to treat the symptoms of schizophrenia (a mental illness that causes disturbed or unusual thinking, loss of interest in life, and strong or inappropriate emotions) in patients who have not been helped by other medications or who have tried to kill themselves and are likely to try to kill or harm themselves again.

Clozapine is in a class of medications called atypical antipsychotics. It works by changing the activity of certain natural substances in the brain.

This medication comes in suspension, tablet, and in an orally disintegrating tablet (tablet that dissolves quickly in the mouth) and is taken usually one to three times a day.

Do not divide or break orally disintegrating tablets. Let the tablet disintegrate in the mouth. The tablets can be allowed to disintegrate, or they may be chewed.

Common side effects of clozapine include sedation, tachycardia (fast heartbeat), and constipation.

Clozapine can also cause drowsiness and dizziness. Do not drive or operate heavy machinery until you know how clozapine affects you.

CYP2D6 is a protein in your body that is involved in the elimination of clozapine and other drugs from your body. Some patients have more or less of this protein in their bodies, affecting how much of the drug gets eliminated. Levels of CYP2D6 can vary greatly between individuals, and those having less of this protein are known as "poor metabolizers." 

CYP2D6 testing is done to determine whether you are a poor metabolizer. If you are a poor metabolizer, the levels of clozapine in your blood can become too high. As a result you may be at an increased risk of having more side effects from clozapine. 

Your doctor may adjust your dose of clozapine if you are a poor metabolizer.

Clozapine is a prescription medication used to treat the symptoms of schizophrenia (a mental illness that causes disturbed or unusual thinking, loss of interest in life, and strong or inappropriate emotions) in patients who have not been helped by other medications or who have tried to kill themselves and are likely to try to kill or harm themselves again.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Clozapine may be found in some form under the following brand names:

• Clozaril

• Fazaclo

• Versacloz

Serious side effects have been reported with clozapine. See the “Clozapine Precautions” section.

Common side effects of clozapine include the following:

• sedation
• dizziness/vertigo
• headache
• tremor
• tachycardia (fast heartbeat)
• low blood pressure
• syncope  (fainting or “passing out”)
• hypersalivation
• sweating
• dry mouth
• visual disturbances
• constipation
• nausea
• fever

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Clozapine can cause a serious blood condition. Your doctor will order certain lab tests before you start your treatment, during your treatment, and for at least 4 weeks after your treatment. Your doctor will order the lab tests once a week at first and may order the tests less often as your treatment continues. If you experience any of the following symptoms, call your doctor immediately: extreme tiredness; weakness; fever, sore throat, chills, or other signs of flu or infection; or sores in your mouth or throat.

A program has been set up by the manufacturers of clozapine to be sure that people do not take clozapine without the necessary monitoring. You, your doctor, and your pharmacist must be registered with the program, and your pharmacist will not dispense your medication unless he or she has received the results of your blood tests. Ask your doctor for more information about this program and how you will receive your medication.

Clozapine may cause seizures. Tell your doctor if you have or have ever had seizures. Do not drive a car, operate machinery, swim, or climb while taking clozapine, because if you suddenly lose consciousness, you could harm yourself or others.

Clozapine may cause myocarditis (swelling of the heart muscle that may be dangerous). If you experience any of the following symptoms, call your doctor immediately: extreme tiredness; difficulty breathing or fast breathing; fever; chest pain; or fast, irregular, or pounding heartbeat.

Clozapine may cause dizziness, lightheadedness, or fainting when you stand up, especially when you first start taking it or when your dose is increased. Tell your doctor if you are taking medications for anxiety such as diazepam (Valium), sleeping pills, or other medications for schizophrenia. Your doctor will probably start you on a low dose of clozapine and gradually increase your dose to give your body time to adjust to the medication and decrease the chance that you will experience this side effect. Talk to your doctor if you do not take clozapine for 2 days or longer. Your doctor will probably tell you to restart your treatment with a low dose of clozapine.

Use in Older Adults:

Studies have shown that older adults with dementia (a brain disorder that affects the ability to remember, think clearly, communicate, and perform daily activities and that may cause changes in mood and personality) who take antipsychotics (medications for mental illness) such as clozapine have an increased chance of death during treatment.

Clozapine is not approved by the Food and Drug Administration (FDA) for the treatment of behavior problems in older adults with dementia. Talk to the doctor who prescribed clozapine if you, a family member, or someone you care for has dementia and is taking this medication.