GENERIC NAME: clozapine
BRAND NAME: Clozaril, FazaClo, Versacloz
DRUG CLASS AND MECHANISM: Clozapine is an anti-psychotic medication that works by blocking receptors in the brain for several neurotransmitters (chemicals that nerves use to communicate with each other) including dopamine type 4 receptors, serotonin type 2 receptors, norepinephrine receptors, acetylcholine receptors, and histamine receptors. Unlike traditional anti-psychotic agents, such as chlorpromazine (Thorazine) and haloperidol (Haldol) as well as the newer anti-psychotics, risperidone (Risperdal) and olanzapine (Zyprexa), clozapine only weakly blocks dopamine type 2 receptors.
PRESCRIBED FOR: Clozapine is use in the management of psychotic disorders including schizophrenia. Because of concern for the side effect of agranulocytosis (see side effects), clozapine should be reserved for patients who have failed to respond to other standard medications or who are at risk for recurring suicidal behavior.
SIDE EFFECTS WARNING:
Clozapine can cause severe neutropenia which is a reduction in the number of white blood cells (absolute neutrophil count or ANC) below 500/μL. Severe neutropenia can lead to serious infection and death. Patients should immediately report symptoms of infection such as fever, weakness, lethargy, or sore throat.
A baseline ANC must be obtained before treatment with clozapine. Patients should have an ANC of at least 1500/μL in general and at least 1000/μL for patients with a condition called benign ethnic neutropenia (BEN).
Patients must have regular ANC monitoring during treatment. Weekly ANC monitoring is required for all patients during the first 6 months of treatment. If a patient's ANC remains equal to or greater than 1500/μL for the first 6 months of treatment, monitoring frequency may be reduced to every 2 weeks for the next 6 months. If the ANC remains equal to or greater than 1500/μL for the second 6 months of continuous therapy, ANC monitoring frequency may be reduced to once every 4 weeks thereafter. The full clozapine FDA prescribing information should be consulted for detailed monitoring recommendations.
Clozapine is not approved for use in dementia-related psychosis. Among elderly patients with dementia-related psychosis, treatment with clozapine is associated with an increased risk of death for unclear reasons.
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