What is the medication clozapine most often used to treat?

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What Is Clozapine and How Does It Work?
What Are Dosages of Clozapine?
Side Effects
Precautions
Interactions

What Is Clozapine and How Does It Work?

Clozapine is an antipsychotic medication that is used to treat severe schizophrenia symptoms in people who have not responded to other medications. It is also used to help reduce the risk of suicidal behavior in people with schizophrenia or similar disorders.

Clozapine is available under the following different brand names: Clozaril, FazaClo ODT, and Versacloz.

What Are Dosages of Clozapine?

Dosages of Clozapine:

Dosage Forms and Strengths

Tablet

25 mg
50 mg
100 mg
200 mg

Tablet, orally disintegrating (FazaClo ODT)

12.5 mg
25 mg
100 mg
150 mg
200 mg

Oral suspension (Versacloz)

Dosage Considerations – Should be Given as Follows:

Schizophrenia

Indicated for reducing the risk of recurrent suicidal behavior in patients with schizophrenia or schizoaffective disorder in patients who are judged to be at chronic risk to re-experience suicidal behavior
Also indicated for treatment-resistant schizophrenia in patients who fail to respond adequately to standard antipsychotic treatment
12.5 mg orally once daily or every 12 hours initially; increased daily in increments of 25-50 mg/day, if well-tolerated, to achieve target dosage of 300-450 mg/day by end of 2 weeks
On occasion, may have to be increased to 600-900 mg/day to obtain an acceptable response
Maintenance: Generally, patients who respond should continue maintenance treatment on their effective dose beyond the acute episode

Dosing Modifications

Strong CYP1A2 inhibitors: Use one-third clozapine dose
Moderate or weak CYP1A2 inhibitors: Monitor for adverse reactions; consider reducing clozapine dose if needed
CYP2D6 or CYP3A4 inhibitors: Monitor for adverse reactions; consider reducing clozapine dose if needed
Strong CYP3A4 inducers: Co-administration not recommended; if the inducer is necessary, clozapine dose may need to be increased
Moderate or weak CYP1A2 or CYP3A4 inducers: Monitor for decreased effectiveness; consider increasing clozapine dose if necessary; consider reducing dose if CYP1A2 or CYP3A4 inducers are discontinued
CYP2D6 poor metabolizers: Clozapine dose reduction may be needed
Significant renal or hepatic impairment: Clozapine dose reduction may be needed

Dosing Considerations

Required laboratory monitoring

Prior to initiating, obtain complete blood count (CBC) with differential, to continue treatment, absolute neutrophil count (ANC) must be monitored regularly
In order to initiate treatment, ANC must be 1500/mm³ or greater for the general population and 1000/mm³ or greater for patients with documented benign ethnic neutropenia
See prescribing information for detailed monitoring requirements, including those for patients with benign ethnic neutropenia

Pediatric: Safety and efficacy not established

Geriatric: A lower initial dosage of 12.5-25 mg/day indicated; may be titrated more slowly than in younger adults

Elderly patients, particularly those with compromised cardiovascular functioning, may be more susceptible to orthostatic hypotension and tachycardia; anticholinergic effects are also common (constipation, confusion, urinary retention)

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; 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.

Because of the risks with this medication, clozapine is available only through a special restricted distribution program. A program has been set up by the manufacturers of clozapine to be sure that people do not take clozapine without the necessary monitoring called the Clozapine Risk Evaluation and Mitigation Strategies (REMS) Program. Your doctor and your pharmacist must be registered with the Clozapine REMS 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. If you experience a seizure, call your doctor immediately or get emergency medical treatment.

Clozapine may cause myocarditis (swelling of the heart muscle that may be dangerous) or cardiomyopathy (enlarged or thickened heart muscle that stops the heart from pumping blood normally). If you experience any of the following symptoms, call your doctor immediately: extreme tiredness; flu like symptoms; 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 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 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. For more information visit the FDA website: http://www.fda.gov/Drugs

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Uses

If you are taking the over-the-counter product to self-treat, read all directions on the product package before taking this medication. If you have any questions, consult your pharmacist. If your doctor has prescribed this medication, take it as directed, usually once daily.

If you are using the chewable tablets, chew each tablet well and swallow. If you are using the rapidly-dissolving tablet, allow the tablet to dissolve on the tongue and then swallow, with or without water. If you are using the liquid form of this medication, measure the dose carefully using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.

The dosage is based on your age, medical condition, and response to treatment. Do not increase your dose or take this medication more often than directed.

Tell your doctor if your allergy symptoms do not improve, if your hives do not improve after 3 days of treatment, or if your hives last more than 6 weeks. Get medical help right away if your condition worsens or if you think you have a serious medical problem (such as a very serious allergic reaction/anaphylaxis).

Side Effects

Drowsiness, tiredness, and dry mouth may occur. Stomach pain may also occur, especially in children. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

If your doctor has prescribed this medication, remember that your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: difficulty urinating, weakness.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Precautions

Before taking cetirizine, tell your doctor or pharmacist if you are allergic to it; or to hydroxyzine; or to levocetirizine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: difficulty urinating (such as due to an enlarged prostate), kidney disease, liver disease.

If you are using this medication to treat hives, tell your doctor right away if you have any of these other symptoms because they may be signs of a more serious condition: hives that are an unusual color, hives that look bruised or blistered, hives that do not itch.

This drug may make you drowsy. Alcohol or marijuana (cannabis) can make you more drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Liquid products may contain sugar. Caution is advised if you have diabetes. Ask your doctor or pharmacist about using this product safely.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk. Consult your doctor before breast-feeding.

Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or other antihistamines (such as chlorpheniramine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

Do not use with any other antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray) because increased side effects may occur.

Cetirizine is very similar to hydroxyzine and levocetirizine. Do not use these medications while using cetirizine.

This medication may interfere with certain laboratory tests (including allergy skin testing), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

Does Cetirizine HCL interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe drowsiness. In children, mental/mood changes (such as restlessness, irritability) may occur before drowsiness.

Notes

Keep all regular medical and laboratory appointments.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Storage

Store at room temperature away from light and moisture. Do not store in the bathroom. Different brands of this medication may have different storage needs. Check the product package for instructions on how to store your brand, or ask your pharmacist. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, except as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.