While clozapine can provide great benefits, it can rarely cause serious, possibly fatal side effects. For this reason, clozapine is used when other treatments have not worked or you cannot take them.
For patients to receive this medication, all doctors, pharmacists, and patients must agree to, understand, and carefully follow the requirements of a patient registry program, developed by the U.S. Food and Drug Administration. These requirements apply in the United States. If you live in Canada or any other country, consult your doctor and pharmacist for your country's regulations.
This medication can cause a serious immune system problem called agranulocytosis (low white blood cells). To make sure you have enough white blood cells, you will need to have a blood test before you begin taking clozapine and then have your blood tested regularly during your treatment. (See also How to Use, Side Effects, and Notes sections.)
Clozapine can also cause seizures, especially in higher doses. Let your doctor or pharmacist know if you have ever had seizures. While taking this medication, avoid driving or other activities during which a sudden loss of consciousness could be dangerous (e.g., operating heavy machinery, swimming).
This medication may rarely cause an inflammation of the heart muscle (myocarditis). Seek immediate medical attention if you have weakness, difficult/rapid breathing, chest pain, or swelling of the ankles/legs. Your risk is highest in the first month of treatment.
Clozapine can cause a big drop in blood pressure, which can make you dizzy or cause you to faint when you stand up. Be sure to get up slowly while taking this medication. This is more likely to occur when your dose of clozapine is increased or if you are also taking a benzodiazepine (e.g., clonazepam, lorazepam, diazepam).
There may be a slightly increased risk of serious, possibly fatal side effects (such as stroke, heart failure, fast/irregular heartbeat, pneumonia) when this medication is used by older adults with dementia. This medication is not approved for the treatment of dementia-related behavior problems. Discuss the risks and benefits of this medication, as well as other effective and possibly safer treatments for dementia-related behavior problems, with the doctor.Who should not take clozapine?
See also Warning section.
This medication is used to treat certain mental/mood disorders (schizophrenia, schizoaffective disorders). Clozapine is a psychiatric medication (anti-psychotic type) that works by helping to restore the balance of certain natural substances (neurotransmitters) in the brain.
Clozapine decreases hallucinations and helps prevent suicide in people who are likely to try to harm themselves. It helps you to think more clearly and positively about yourself, feel less nervous, and take part in everyday life.
Take this medication by mouth with or without food, as directed by your doctor. If you are taking the tablets that dissolve in the mouth, carefully remove each tablet from the blister pack immediately before taking your dose. Allow the tablets to dissolve on your tongue and swallow. You do not need to take the dissolving tablets with water. Discard any dissolving tablets that have been previously exposed to air due to opened/damaged packaging. Do not save them for your next dose.
It is important to begin taking this drug at a low dose, increasing your dose slowly, to lessen side effects such as dizziness, drowsiness and seizures. Follow your doctor's instructions exactly. Your dosage is based on your medical condition and response to therapy. Since clozapine can cause a decrease in white blood cells, you will need to get blood tests done regularly as directed. Be sure to keep all appointments for these laboratory tests.
If you miss your doses for longer than a day or two, consult your doctor for a new schedule to get back to the dose you were on (see Missed Dose section). Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same time(s) each day.
Do not stop taking clozapine without consulting your doctor. Some conditions may become worse when the drug is suddenly stopped. Also, you may experience symptoms such as severe sweating, headache, nausea, vomiting, and diarrhea. To prevent these symptoms while you are stopping treatment with this drug, your doctor may reduce your dose gradually. Consult your doctor or pharmacist for more details. Report any new or worsening symptoms immediately.
It may take several weeks before the full benefit of this drug takes effect. Inform your doctor if your condition persists or worsens.
Drooling, drowsiness, dizziness, headache, shaking (tremor), vision problems (e.g., blurred vision), weight gain, and constipation may occur. Many of these effects (especially drowsiness) lessen as your body gets used to the medication. If any of these effects persist or worsen, contact your doctor or pharmacist promptly.
To prevent constipation, maintain a diet adequate in fiber, drink plenty of water, and exercise. If you become constipated while using this drug, consult your pharmacist for help in selecting a laxative (e.g., stimulant-type with stool softener).
Remember that your doctor has prescribed this medication because he or she 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.
This medication may infrequently make your blood sugar level rise, which can cause or worsen diabetes. Rarely, very serious conditions such as diabetic coma may occur. Tell your doctor immediately if you develop symptoms of high blood sugar, such as increased thirst and urination. If you already have diabetes, be sure to check your blood sugars regularly. Your doctor may need to adjust your diabetes medication, exercise program, or diet.
This drug may also cause significant weight gain and a rise in your cholesterol (or triglyceride) levels. These effects, along with diabetes, may increase your risk for developing heart disease. Discuss the risks and benefits of treatment with your doctor.
Tell your doctor immediately if any of these unlikely but serious side effects occur: facial/muscle twitching, signs of infection (e.g., severe tiredness, fever, persistent sore throat), seizures, uncontrollable movements.
Seek immediate medical attention if any of these rare but very serious side effects occur: severe dizziness, fainting, mental/mood changes, difficulty breathing with exercise, swollen legs/feet, sudden weakness, pain/redness/swelling of the arms/legs, chest pain, persistent nausea/vomiting, stomach/abdominal pain, yellowing of eyes/skin.
This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms: fever, muscle stiffness/pain/tenderness/weakness, severe tiredness, severe confusion, sweating, fast/irregular heartbeat, dark urine, change in the amount of urine.
A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: 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 -
See also Warning and Side Effects sections.
Before taking clozapine, tell your doctor or pharmacist if you are allergic to it 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.
This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: history of blood disorders (e.g., leukemia, low white blood cell count), history of blood disorders caused by clozapine, serious bowel problems (e.g., paralytic ileus), seizures not controlled by medication.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: bowel problems (e.g., irritable bowel syndrome), breathing problems, diabetes/family history of diabetes, high cholesterol/triglyceride levels, glaucoma, heart problems, kidney problems, liver problems, obesity/family history of obesity, seizures, difficulty urinating (e.g., prostate problems).
Clozapine may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.
The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may affect the heart rhythm. Before using clozapine, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).
Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using clozapine safely.
This drug may make you dizzy or drowsy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely. Limit alcoholic beverages.
To minimize dizziness and lightheadedness, get up slowly when rising from a seated or lying position.
Tell your doctor if you are a descendent of Ashkenazi Jews because you may be at a higher risk for a drop in your white blood cells.
Before having surgery, tell your doctor or dentist that you are using this medication.
The rapidly dissolving form of this drug may contain aspartame or phenylalanine. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame (or phenylalanine), consult your doctor or pharmacist about the safe use of this medicine.
Older adults may be more sensitive to the side effects of this drug, especially constipation, dizziness, and QT prolongation (see above). Dizziness can increase the risk of falling.
During pregnancy, this medication should be used only when clearly needed. Babies born to mothers who have used this drug during the last 3 months of pregnancy may infrequently develop symptoms including muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. If you notice any of these symptoms in your newborn especially during their first month, tell the doctor right away.
Since untreated mental/mood problems (such as schizophrenia, schizoaffective disorders) can be a serious condition, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately discuss with your doctor the benefits and risks of using this medication during pregnancy.
This medication may pass into breast milk and have undesirable effects on a nursing infant. Breast feeding is not recommended while taking clozapine. Consult your doctor before breast-feeding.
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.
A product that may interact with this drug is: metoclopramide.
Other medications can affect the removal of clozapine from your body, which may affect how clozapine works. Examples include fluoxamine, rifamycins (such as rifabutin, rifampin), St. John's wort, drugs used to treat seizures (such as carbamazepine, phenytoin), among others.
Tell your doctor or pharmacist if you are taking other products that cause drowsiness including alcohol, antihistamines (such as cetirizine, diphenhydramine), drugs for sleep or anxiety (such as alprazolam, diazepam, zolpidem), muscle relaxants, and narcotic pain relievers (such as codeine).
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.
Cigarette smoking decreases blood levels of this medication. Tell your doctor if you smoke or if you have recently stopped smoking.
If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.
Do not share this medication with others.
Laboratory tests (e.g., blood tests) should be performed weekly for the first 6 months of treatment. During the next 6 months, they should be performed at least every 2 weeks. After that, they should be performed regularly no less often than once a month while you are on clozapine and for at least 4 weeks after you stop taking it. Your testing schedule may be changed if you develop a low white blood cell count, or if your treatment is interrupted. Your doctor may also order other laboratory and/or medical tests (e.g., liver function, blood sugar, weight, blood cholesterol/triglyceride levels) from time to time. Consult your doctor for more details.
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 and resume your usual dosing schedule. If you miss doses for longer than a day or two, consult your doctor for a new schedule to get back to the dose you were taking. Do not double the dose to catch up.
Store at room temperature no higher than 86 degrees F (30 degrees C) away from light and moisture. Store the dissolving tablets at 77 degrees F (25 degrees C) in their blister packets, and do not remove each dose until immediately before taking. Brief storage between 59-86 degrees F (15-30 degrees C) is permitted. Do not store in the bathroom. Keep all medicines 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 for more details about how to safely discard your product.
Information last revised March 2015. Copyright(c) 2015 First Databank, Inc.
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