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Clozapine (Clozapine) - Side Effects and Adverse Reactions

 
 



ADVERSE REACTIONS

Associated with Discontinuation of Treatment

Sixteen percent of 1,080 patients who received clozapine in premarketing clinical trials discontinued treatment due to an adverse event, including both those that could be reasonably attributed to clozapine treatment and those that might more appropriately be considered intercurrent illness. The more common events considered to be causes of discontinuation included: CNS, primarily drowsiness/sedation, seizures, dizziness/syncope; cardiovascular, primarily tachycardia, hypotension and ECG changes; gastrointestinal, primarily nausea/vomiting; hematologic, primarily leukopenia/granulocytopenia/agranulocytosis; and fever. None of the events enumerated accounts for more than 1.7% of all discontinuations attributed to adverse clinical events.

Extrapyramidal Symptoms

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. Clozapine, an atypical antipsychotic, is associated with a low incidence of dystonia (see WARNINGS: Tardive Dyskinesia).

Commonly Observed

Adverse events observed in association with the use of clozapine in clinical trials at an incidence of greater than 5% were: central nervous system complaints, including drowsiness/sedation, dizziness/vertigo, headache and tremor; autonomic nervous system complaints, including salivation, sweating, dry mouth and visual disturbances; cardiovascular findings, including tachycardia, hypotension and syncope; and gastrointestinal complaints, including constipation and nausea; and fever. Complaints of drowsiness/sedation tend to subside with continued therapy or dose reduction. Salivation may be profuse, especially during sleep, but may be diminished with dose reduction.

Incidence in Clinical Trials

The following table enumerates adverse events that occurred at a frequency of 1% or greater among clozapine patients who participated in clinical trials. These rates are not adjusted for duration of exposure.

Treatment-Emergent Adverse Experience Incidence Among Patients Taking Clozapine in Clinical Trials (excluding the InterSePTTM Study) (N = 842) (Percentage of Patients Reporting)
Body System/
     Adverse EventEvents reported by at least 1% of clozapine patients are included.
Percent
Central Nervous System 
     Drowsiness/Sedation39
     Dizziness/Vertigo19
     Headache7
     Tremor6
     Syncope6
     Disturbed sleep/ Nightmares4
     Restlessness4
     Hypokinesia/Akinesia4
     Agitation4
     Seizures (convulsions)3Rate based on population of approximately 1,700 exposed during premarket clinical evaluation of clozapine.
     Rigidity3
     Akathisia3
     Confusion3
     Fatigue2
     Insomnia2
     Hyperkinesia1
     Weakness1
     Lethargy1
     Ataxia1
     Slurred speech1
     Depression1
     Epileptiform movements/Myoclonic jerks1
     Anxiety1
Cardiovascular 
     Tachycardia25
     Hypotension9
     Hypertension4
     Chest pain/Angina1
     ECG Change/Cardiac abnormality1
Gastrointestinal 
     Constipation14
     Nausea5
     Abdominal discomfort/Heartburn4
     Nausea/Vomiting3
     Vomiting3
     Diarrhea2
     Liver test abnormality1
     Anorexia1
Urogenital 
     Urinary abnormalities2
     Incontinence1
     Abnormal ejaculation1
     Urinary urgency/frequency1
     Urinary retention1
Autonomic Nervous System 
     Salivation31
     Sweating6
     Dry mouth6
     Visual disturbances5
Integumentary (Skin) 
     Rash2
Musculoskeletal 
     Muscle weakness1
     Pain (back, neck, legs)1
     Muscle spasm1
     Muscle pain, ache1
Respiratory 
     Throat discomfort1
     Dyspnea, shortness of breath1
     Nasal congestion1
Hemic/Lymphatic 
     Leukopenia/Decreased WBC/Neutropenia3
     Agranulocytosis1
     Eosinophilia1
Miscellaneous 
     Fever5
     Weight gain4
     Tongue numb/sore1

The following table enumerates adverse events that occurred at a frequency of 10% for either treatment group in patients who took at least one dose of study medication during their participation in InterSePT, which was an adequate and well controlled 2-year study evaluating the efficacy of clozapine relative to Zyprexa in reducing the risk of emergent suicidal behavior in patients with schizophrenia or schizoaffective disorder. These rates are not adjusted for duration of exposure.

Treatment-Emergent Adverse Experience IncidenceAEs are listed by frequency in clozapine group, and included in the table are those for which the risk ratio of clozapine over Zyprexa or of Zyprexa over clozapine was greater than 1.5.  Among Patients Taking clozapine or Zyprexa® (olanzapine) in the InterSePTTM Study (Percentage of Patients Reporting)
  Clozapine
N = 479
% Reporting

Zyprexa®
N = 477
% Reporting

Adverse Events   
Salivary hypersecretion48%6%
Somnolence46%25%
Weight increased31%56%
Dizziness (excluding vertigo)27%12%
Constipation25%10%
Insomnia NEC20%33%
Nausea17%10%
Vomiting NOS17%9%
Dyspepsia14%8%
NEC - not elsewhere classified
NOS - not otherwise specified

Other Events Observed During the Premarketing Evaluation of Clozapine

This section reports additional, less frequent adverse events which occurred among the patients taking clozapine in clinical trials. Various adverse events were reported as part of the total experience in these clinical studies; a causal relationship to clozapine treatment cannot be determined in the absence of appropriate controls in some of the studies. The table above enumerates adverse events that occurred at a frequency of at least 1% of patients treated with clozapine. The list below includes all additional adverse experiences reported as being temporally associated with the use of the drug which occurred at a frequency less than 1%, enumerated by organ system.

Central Nervous System: loss of speech, amentia, tics, poor coordination, delusions/hallucinations, involuntary movement, stuttering, dysarthria, amnesia/memory loss, histrionic movements, libido increase or decrease, paranoia, shakiness, Parkinsonism, and irritability.

Cardiovascular System: edema, palpitations, phlebitis/thrombophlebitis, cyanosis, premature ventricular contraction, bradycardia, and nosebleed.

Gastrointestinal System: abdominal distention, gastroenteritis, rectal bleeding, nervous stomach, abnormal stools, hematemesis, gastric ulcer, bitter taste, and eructation.

Urogenital System: dysmenorrhea, impotence, breast pain/discomfort, and vaginal itch/infection.

Autonomic Nervous System: numbness, polydipsia, hot flashes, dry throat, and mydriasis.

Integumentary (Skin): pruritus, pallor, eczema, erythema, bruise, dermatitis, petechiae, and urticaria.

Musculoskeletal System: twitching and joint pain.

Respiratory System: coughing, pneumonia/pneumonia-like symptoms, rhinorrhea, hyperventilation, wheezing, bronchitis, laryngitis, and sneezing.

Hemic and Lymphatic System: anemia and leukocytosis.

Miscellaneous: chills/chills with fever, malaise, appetite increase, ear disorder, hypothermia, eyelid disorder, bloodshot eyes, and nystagmus.

Post-Marketing Clinical Experience

Post-marketing experience has shown an adverse experience profile similar to that presented above. Voluntary reports of adverse events temporally associated with clozapine not mentioned above that have been received since market introduction and that may have no causal relationship with the drug include the following:

Central Nervous System:  delirium; EEG abnormal; exacerbation of psychosis; myoclonus; overdose; paresthesia; possible mild cataplexy; and status epilepticus.

Cardiovascular System:  atrial or ventricular fibrillation and periorbital edema.

Gastrointestinal System:  acute pancreatitis; dysphagia; fecal impaction; intestinal obstruction/paralytic ileus; and salivary gland swelling.

Hepatobiliary System:  cholestasis; hepatitis; and jaundice.

Hepatic System: cholestasis.

Urogenital System:  acute interstitial nephritis and priapism.

Integumentary (Skin):  hypersensitivity reactions: photosensitivity, vasculitis, erythema multiforme, and Stevens-Johnson Syndrome.

Metabolic and Nutritional Disorders: hypercholesterolemia (very rare); and hypertriglyceridemia (very rare).

Musculoskeletal System:  myasthenic syndrome and rhabdomyolysis.

Respiratory System:  aspiration and pleural effusion.

Hemic and Lymphatic System:  deep vein thrombosis; elevated hemoglobin/hematocrit; ESR increased; pulmonary embolism; sepsis; thrombocytosis; and thrombocytopenia.

Vision Disorders: narrow angle glaucoma.

Miscellaneous:  CPK elevation; hyperglycemia; hyperuricemia; hyponatremia; and weight loss.



REPORTS OF SUSPECTED CLOZAPINE SIDE EFFECTS / ADVERSE REACTIONS

Below is a sample of reports where side effects / adverse reactions may be related to Clozapine. The information is not vetted and should not be considered as verified clinical evidence.

Possible Clozapine side effects / adverse reactions in 65 year old female

Reported by a health professional (non-physician/pharmacist) from Netherlands on 2011-10-03

Patient: 65 year old female

Reactions: Humerus Fracture, Pulmonary Toxicity, Drug Interaction, Toxicity TO Various Agents, Bronchoalveolar Lavage Abnormal, Interstitial Lung Disease, Respiratory Failure, Antipsychotic Drug Level Above Therapeutic, Inflammation

Adverse event resulted in: death, hospitalization

Suspect drug(s):
Clozapine

Other drugs received by patient possibly interacting with the suspect drug:
Clozapine
    Dosage: 300 mg, qd

Amitriptyline HCL
    Dosage: 50 mg,

Amitriptyline HCL
    Dosage: 250 mg, qd

Other drugs received by patient: Acetaminophen; Promethazine



Possible Clozapine side effects / adverse reactions in 51 year old male

Reported by a consumer/non-health professional from Finland on 2011-10-03

Patient: 51 year old male

Reactions: Overdose, Loss of Consciousness

Adverse event resulted in: death

Suspect drug(s):
Clozapine



Possible Clozapine side effects / adverse reactions in 65 year old female

Reported by a physician from Netherlands on 2011-10-03

Patient: 65 year old female

Reactions: Pulmonary Toxicity, Humerus Fracture, Drug Interaction, Toxicity TO Various Agents, Bronchoalveolar Lavage Abnormal, Interstitial Lung Disease, Respiratory Failure, Antipsychotic Drug Level Above Therapeutic, Inflammation

Adverse event resulted in: death, hospitalization

Suspect drug(s):
Clozapine

Other drugs received by patient possibly interacting with the suspect drug:
Amitriptyline HCL
    Dosage: 250 mg, qd

Clozapine
    Dosage: 300 mg, qd

Amitriptyline HCL
    Dosage: 50 mg,

Other drugs received by patient: Acetaminophen; Promethazine



See index of all Clozapine side effect reports >>

Drug label data at the top of this Page last updated: 2008-10-30

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