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Clozaril

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Clozaril

Side Effects
Interactions

SIDE EFFECTS

The following adverse reactions are discussed in more detail in other sections of the labeling:

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

The most commonly reported adverse reactions ( ≥ 5%) across CLOZARIL clinical trials were: CNS reactions, including sedation, dizziness/vertigo, headache, and tremor; cardiovascular reactions, including tachycardia, hypotension, and syncope; autonomic nervous system reactions, including hypersalivation, sweating, dry mouth, and visual disturbances; gastrointestinal reactions, including constipation and nausea; and fever. Table 8 summarizes the most commonly reported adverse reactions ( ≥ 5%) in CLOZARIL-treated patients (compared to chlorpromazine-treated patients) in the pivotal, 6-week, controlled trial in treatment-resistant schizophrenia.

Table 8: Common Adverse Reactions ( ≥ 5%) in the 6-Week, Randomized, Chlorpromazine-controlled Trial in Treatment-Resistant Schizophrenia

Adverse Reaction CLOZARIL
(N = 126)
(%)
Chlorpromazine
(N = 142)
(%)
Sedation 21 13
Tachycardia 17 11
Constipation 16 12
Dizziness 14 16
Hypotension 13 38
Fever (hyperthermia) 13 4
Hypersalivation 13 1
Hypertension 12 5
Headache 10 10
Nausea/vomiting 10 12
Dry mouth 5 20

Table 9 summarizes the adverse reactions reported in CLOZARIL-treated patients at a frequency of 2% or greater across all CLOZARIL studies (excluding the 2-year InterSePT™ Study). These rates are not adjusted for duration of exposure.

Table 9: Adverse Reactions ( ≥ 2%) Reported in CLOZARIL-treated Patients (N=842) across all CLOZARIL Studies (excluding the 2-year InterSePT™ Study)

Body System Adverse Reaction* CLOZARIL
N = 842
Percentage of Patients
Central Nervous System
  Drowsiness/Sedation 39
  Dizziness/Vertigo 19
  Headache 7
  Tremor 6
  Syncope 6
  Disturbed Sleep/Nightmares 4
  Restlessness   4
  Hypokinesia/Akinesia 4
  Agitation 4
  Seizures (convulsions)   3†
  Rigidity 3
  Akathisia 3
  Confusion 3
  Fatigue 2
  Insomnia 2
Cardiovascular
  Tachycardia 25†
  Hypotension 9
  Hypertension 4
Gastrointestinal
  Constipation 14
  Nausea 5
  Abdominal Discomfort/Heartburn 4
  Nausea/Vomiting 3
  Vomiting 3
  Diarrhea 2
Urogenital
  Urinary Abnormalities 2
Autonomic Nervous System
  Salivation 31
  Sweating 6
  Dry Mouth 6
  Visual Disturbances 5
Skin
  Rash 2
Hemic/Lymphatic
  Leukopenia/Decreased WBC/Neutropenia 3
Miscellaneous
  Fever 5
  Weight Gain 4
†Rate based on population of approximately 1700 exposed during premarket clinical evaluation of CLOZARIL.

Table 10 summarizes the most commonly reported adverse reactions ( ≥ 10% of the CLOZARIL or olanzapine group) in the InterSePT™ Study. This was an adequate and well-controlled, two-year study evaluating the efficacy of CLOZARIL relative to olanzapine in reducing the risk of suicidal behavior in patients with schizophrenia or schizoaffective disorder. The rates are not adjusted for duration of exposure.

Table 10: Incidence of Adverse Reactions in Patients Treated with CLOZARIL or Olanzapine in the InterSePT™ Study ( ≥ 10% in the CLOZARIL or olanzapine group)

Adverse Reactions CLOZARIL
N = 479
% Reporting
Olanzapine
N = 477
% Reporting
Salivary hypersecretion 48% 6%
Somnolence 46% 25%
Weight increased 31% 56%
Dizziness (excluding vertigo) 27% 12%
Constipation 25% 10%
Insomnia 20% 33%
Nausea 17% 10%
Vomiting 17% 9%
Dyspepsia 14% 8%

Dystonia

Class effect: Symptoms of dystonia, prolonged abnormal contractions of muscle groups, may occur in susceptible individuals during the first few days of treatment. Dystonic symptoms include: spasm of the neck muscles, sometimes progressing to tightness of the throat, swallowing difficulty, difficulty breathing, and/or protrusion of the tongue. While these symptoms can occur at low doses, they occur more frequently and with greater severity with high potency and at higher doses of first generation antipsychotic drugs. An elevated risk of acute dystonia is observed in males and younger age groups.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of clozapine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Central Nervous System

Delirium, EEG abnormal, myoclonus, paresthesia, possible cataplexy, status epilepticus, obsessive compulsive symptoms, and post-discontinuation cholinergic rebound adverse reactions.

Cardiovascular System

Atrial or ventricular fibrillation, ventricular tachycardia, QT interval prolongation, Torsades de Pointes, myocardial infarction, cardiac arrest, and periorbital edema.

Gastrointestinal System

Acute pancreatitis, dysphagia, salivary gland swelling.

Hepatobiliary System

Cholestasis, hepatitis, jaundice, hepatotoxicity, hepatic steatosis, hepatic necrosis, hepatic fibrosis, hepatic cirrhosis, liver injury (hepatic, cholestatic, and mixed), and liver failure.

Urogenital System

Acute interstitial nephritis, nocturnal enuresis, priapism, and renal failure.

Skin

Hypersensitivity reactions: photosensitivity, vasculitis, erythema multiforme, and Stevens-Johnson Syndrome.

Musculoskeletal System

Myasthenic syndrome and rhabdomyolysis.

Respiratory System

Aspiration, pleural effusion, pneumonia, lower respiratory tract infection.

Hemic and Lymphatic System

Deep-vein thrombosis, elevated hemoglobin/hematocrit, erythrocyte sedimentation rate (ESR) increased, sepsis, thrombocytosis, and thrombocytopenia.

Vision Disorders

Narrow-angle glaucoma.

Miscellaneous

Creatine phosphokinase elevation, hyperuricemia, hyponatremia, and weight loss.

Read the Clozaril (clozapine) Side Effects Center for a complete guide to possible side effects

DRUG INTERACTIONS

Potential for Other Drugs to Affect CLOZARIL

Clozapine is a substrate for many cytochrome P450 isozymes, in particular CYP1A2, CYP3A4, and CYP2D6. Use caution when administering CLOZARIL concomitantly with drugs that are inducers or inhibitors of these enzymes.

CYP1A2 Inhibitors

Concomitant use of CLOZARIL and CYP1A2 inhibitors can increase plasma levels of clozapine, potentially resulting in adverse reactions. Reduce the CLOZARIL dose to one third of the original dose when CLOZARIL is coadministered with strong CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin, or enoxacin). The CLOZARIL dose should be increased to the original dose when coadministration of strong CYP1A2 inhibitors is discontinued [see DOSAGE AND ADMINISTRATION, CLINICAL PHARMACOLOGY].

Moderate or weak CYP1A2 inhibitors include oral contraceptives and caffeine. Monitor patients closely when CLOZARIL is coadministered with these inhibitors. Consider reducing the CLOZARIL dosage if necessary [see DOSAGE AND ADMINISTRATION].

CYP2D6 and CYP3A4 Inhibitors

Concomitant treatment with CLOZARIL and CYP2D6 or CYP3A4 inhibitors (e.g., cimetidine, escitalopram, erythromycin, paroxetine, bupropion, fluoxetine, quinidine, duloxetine, terbinafine, or sertraline) can increase clozapine levels and lead to adverse reactions [see CLINICAL PHARMACOLOGY]. Use caution and monitor patients closely when using such inhibitors. Consider reducing the CLOZARIL dose [see DOSAGE AND ADMINISTRATION].

CYP1A2 and CYP3A4 Inducers

Concomitant treatment with drugs that induce CYP1A2 or CYP3A4 can decrease the plasma concentration of clozapine, resulting in decreased effectiveness of CLOZARIL. Tobacco smoke is a moderate inducer of CYP1A2. Strong CYP3A4 inducers include carbamazepine, phenytoin, St. John's wort, and rifampin. It may be necessary to increase the CLOZARIL dose if used concomitantly with inducers of these enzymes. However, concomitant use of CLOZARIL and strong CYP3A4 inducers is not recommended [see DOSAGE AND ADMINISTRATION].

Consider reducing the CLOZARIL dosage when discontinuing coadministered enzyme inducers; because discontinuation of inducers can result in increased clozapine plasma levels and an increased risk of adverse reactions [see DOSAGE AND ADMINISTRATION].

Drugs that Cause QT Interval Prolongation

Use caution when administering concomitant medications that prolong the QT interval or inhibit the metabolism of clozapine. Drugs that cause QT prolongation include: specific antipsychotics (e.g., ziprasidone, iloperidone, chlorpromazine, thioridazine, mesoridazine, droperidol, and pimozide), specific antibiotics (e.g., erythromycin, gatifloxacin, moxifloxacin, sparfloxacin), Class 1A antiarrhythmics (e.g., quinidine, procainamide) or Class III antiarrhythmics (e.g., amiodarone, sotalol), and others (e.g., pentamidine, levomethadyl acetate, methadone, halofantrine, mefloquine, dolasetron mesylate, probucol or tacrolimus) [see WARNINGS AND PRECAUTIONS].

Potential for CLOZARIL to Affect Other Drugs

Concomitant use of CLOZARIL with other drugs metabolized by CYP2D6 can increase levels of these CYPD26 substrates. Use caution when coadministering CLOZARIL with other drugs that are metabolized by CYP2D6. It may be necessary to use lower doses of such drugs than usually prescribed. Such drugs include specific antidepressants, phenothiazines, carbamazepine, and Type 1C antiarrhythmics (e.g., propafenone, flecainide, and encainide).

Read the Clozaril Drug Interactions Center for a complete guide to possible interactions

Last reviewed on RxList: 8/2/2013
This monograph has been modified to include the generic and brand name in many instances.

Side Effects
Interactions
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Clozaril - User Reviews

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