Class Name(s):

• 28:16.08.04 Atypical Antipsychotics

Pronunciation:

• (kloe' za peen)

Brand Name(s):

• Clozaril^®
• FazaClo^® ODT¶
• Versacloz^®; also available generically

IMPORTANT WARNING:

Clozapine can cause severe or life-threatening decrease in the number of white blood cells in your blood. Your doctor will order lab tests during your treatment to check the number of white blood cells in your blood. A decrease in the number of white blood cells in your body may increase the risk that you will develop a serious infection. 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; unusual vaginal discharge or itching; sores in your mouth or throat; wounds that take a long time to heal; pain or burning while urinating; sores or pain in or around your rectal area; or abdominal pain.

Clozapine may cause seizures. Tell your doctor if you have or have ever had seizures, a head injury, or if you drink large amounts of alcohol. 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. If you experience a seizure, call your doctor immediately or get emergency medical treatment.

Clozapine may cause serious or life-threatening heart inflammation or swelling. Clozapine may also cause your heart to enlarge or harden. This may cause the heart to be unable to pump blood normally. If you experience any of the following symptoms, call your doctor immediately: extreme tiredness; flu-like symptoms; swollen legs, ankles, or feet; difficulty breathing or fast breathing; fever; chest pain; dizziness; or fast, irregular, or pounding heartbeat.

Clozapine may cause potentially life-threatening low blood pressure and slow heart rates that can lead to 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 have or have had a heart attack, heart failure, or a slow, irregular heartbeat or are taking medications for high blood pressure. Also tell your doctor if you have severe vomiting or diarrhea or signs of dehydration now, or if you develop these symptoms at any time during your treatment. Your doctor will probably start you on a low dose of clozapine and gradually increase your dose. This will 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. If you experience any of the following symptoms, call your doctor immediately: fainting or slow or irregular heartbeat.

Use in Older Adults:

Older adults with dementia (loss of memory and brain function) who take certain 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. For more information visit http://www.fda.gov/Drugs

WHY is this medicine prescribed?

Clozapine is used to treat schizophrenia (a mental illness that affects how a person thinks, feels or behaves) in certain people. Clozapine is in a class of medications called atypical antipsychotics. It works by changing the activity of certain natural substances in the brain.

HOW should this medicine be used?

Clozapine comes as a tablet, an orally disintegrating tablet (tablet that dissolves quickly in the mouth), and an oral suspension (liquid) to take by mouth. It is usually taken once or twice daily. Take clozapine at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take clozapine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Do not try to push the orally disintegrating tablet through the foil packaging. Instead, use dry hands to peel back the foil. Immediately take out the tablet and place it on your tongue. The tablet will quickly dissolve and can be swallowed with saliva. No water is needed to swallow disintegrating tablets.

To measure clozapine oral suspension, follow these steps:

1. Make sure the cap is tight on the oral suspension container by turning the cap clockwise (to the right). Shake the bottle up and down for 10 seconds before use.
2. Remove the bottle cap by pushing down on the cap, then turn it counterclockwise (to the left). The first time you open a new bottle, push the adaptor into the bottle until the top of the adaptor is lined up with the top of the bottle.
3. If your dose is 1 mL or less, use the smaller (1 mL) oral syringe. If your dose is more than 1 mL, use the larger (9 mL) oral syringe.
4. Fill the oral syringe with by air by drawing back the plunger. Then insert the open tip of the oral syringe into the adaptor. Push all the air from the oral syringe into the bottle by pushing down on the plunger.
5. While holding the oral syringe in place, carefully turn the bottle upside down. Draw some of the medication out of the bottle into the oral syringe by pulling back on the plunger. Be careful not to pull the plunger all the way out.
6. You will see a small amount of air near the end of the plunger in the oral syringe. Push on the plunger so the medication goes back into the bottle and the air disappears. Pull back on the plunger to draw your correct medication dose into the oral syringe.
7. While still holding the oral syringe in the bottle, carefully turn the bottle upwards so the syringe is on top. Remove the oral syringe from the bottle neck adaptor without pushing on the plunger. Take the medication right after you draw it into the oral syringe. Do not prepare a dose and store it in the syringe for later use.
8. Place the open tip of the oral syringe into one side of your mouth. Tightly close your lips around the oral syringe and push on the plunger slowly as the liquid goes into your mouth. Swallow the medication slowly as it goes into your mouth.
9. Leave the adaptor in the bottle. Place the cap back on the bottle and turn it clockwise (to the right) to tighten it.
10. Rinse the oral syringe with warm tap water after each use. Fill a cup with water and place the tip of the oral syringe into the water in the cup. Pull back on the plunger and draw the water into the oral syringe. Push on the plunger to squirt the water into a sink or a separate container until the oral syringe is clean. Allow the oral syringe air dry and dispose of any leftover rinse water.

Clozapine controls schizophrenia but does not cure it. It may take several weeks or longer before you feel the full benefit of clozapine. Continue to take clozapine even if you feel well. Do not stop taking clozapine without talking to your doctor. Your doctor will probably want to decrease your dose gradually.

Are there OTHER USES for this medication?

This medication should not be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking clozapine,

• tell your doctor and pharmacist if you are allergic to this drug, any part of this drug, or any other drugs, foods or substances. Tell your doctor or pharmacist about the allergy and what symptoms you had.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take while taking clozapine. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• the following herbal product may interact with clozapine: St. John's wort. Be sure to let your doctor and pharmacist know that you are taking this medication before you start taking clozapine. Do not start this medication while taking clozapine without discussing with your healthcare provider.
• in addition to the condition listed in the IMPORTANT WARNING section, tell your doctor if you or anyone in your family has ever had a prolonged QT interval (a rare heart problem that may cause irregular heartbeat, fainting, or sudden death. Also, tell your doctor if you have or have ever had low blood levels of magnesium or potassium in your blood; diarrhea; constipation; problems urinating; prostate (a male reproductive gland) problems; diabetes; dyslipidemia (high cholesterol levels); paralytic ileus (condition in which food cannot move through the intestine); glaucoma; high or low blood pressure; trouble keeping your balance; or heart, kidney, lung, or liver disease. Also tell your doctor if you have ever had to stop taking a medication for mental illness because of severe side effects.
• tell your doctor if you are pregnant, especially if you are in the last few months of your pregnancy, or if you plan to become pregnant or are breastfeeding. If you become pregnant while taking clozapine, call your doctor. Clozapine may cause problems in newborns following delivery if it is taken during the last months of pregnancy.
• ask your doctor about the safe use of alcoholic beverages while you are taking clozapine. Alcohol can make the side effects from clozapine worse.
• tell your doctor if you use tobacco products. Cigarette smoking may decrease the effectiveness of this medication. Your doctor may tell you not to smoke while you are taking clozapine.
• you should know that you may experience hyperglycemia (increases in your blood sugar) while you are taking this medication, even if you do not already have diabetes. If you have schizophrenia, you are more likely to develop diabetes than people who do not have schizophrenia, and taking clozapine or similar medications may increase this risk. Tell your doctor immediately if you have any of the following symptoms while you are taking clozapine: extreme thirst, frequent urination, extreme hunger, blurred vision, or weakness. It is very important to call your doctor as soon as you have any of these symptoms, because high blood sugar can cause a serious condition called ketoacidosis. Ketoacidosis may become life-threatening if it is not treated at an early stage. Symptoms of ketoacidosis include: dry mouth, nausea and vomiting, shortness of breath, breath that smells fruity, and decreased consciousness.
• if you have phenylketonuria (PKU, an inherited condition in which a special diet must be followed to prevent damage to your brain that can cause severe intellectual disability), you should know that the orally disintegrating tablets contain aspartame that forms phenylalanine.
• You should know that you may gain weight while you are taking this medication. You and your doctor should check your weight regularly while you are taking clozapine.

What SPECIAL DIETARY instructions should I follow?

Talk to your doctor about drinking caffeinated beverages while taking this medicine.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

If you miss taking clozapine for more than 2 days, you should call your doctor before taking any more medication. Your doctor may want to restart your medication at a lower dose.

What SIDE EFFECTS can this medicine cause?

Clozapine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• drowsiness
• dizziness, feeling unsteady, or having trouble keeping your balance
• increased salivation
• dry mouth
• restlessness
• headache

Some side effects can be serious. If you experience any of the following symptoms or those listed in the IMPORTANT WARNINGS or SPECIAL PRECAUTIONS sections, call your doctor immediately:

• constipation; nausea; stomach swelling or pain; or vomiting
• shaking hands that you cannot control
• unusual movements of your face or body that you cannot control
• falling
• difficulty urinating or loss of bladder control
• fever, sweating, confusion, fast or irregular heartbeat, or severe muscle stiffness
• changes in vision
• shakiness
• changes in behavior
• loss of appetite, nausea, vomiting, pain in the upper right part of the stomach, lack of energy, unusual bleeding or bruising, or yellowing of the skin or eyes
• chest pain; sudden shortness of breath or difficulty breathing; swelling of a leg or arm; leg pain; redness, discoloration, or warmth in the legs or arms

Clozapine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include the following:

• dizziness
• fainting
• slow breathing
• change in heartbeat
• loss of consciousness
• increased salivation or drooling
• seizure

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light and excess heat and moisture (not in the bathroom). Do not refrigerate or freeze the oral suspension.

Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach http://www.upandaway.org

Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website http://goo.gl/c4Rm4p for more information.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to clozapine.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

^¶ This branded product is no longer on the market. Generic alternatives may be available.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™ Copyright, 2025. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: May 15, 2025.