During an outpatient psychiatric evaluation, a -year-old male with treatment-resistant schizophrenia is prescribed clozapine. His previous medication trials, which included maximum tolerated doses of olanzapine and haloperidol, failed to control his auditory hallucinations. He is otherwise healthy, and his baseline physical examination and laboratory studies are completely normal. To comply with safety protocols and prevent a specific life-threatening hematologic complication, which of the following parameters must be evaluated on a strictly scheduled basis for this patient?
- Absolute neutrophil countAnswer
- BProthrombin time and activated partial thromboplastin time
- CSerial transthoracic echocardiography
- DWeekly fasting lipid panels
- ECytochrome P450 enzyme activity assays
Answer
Absolute neutrophil count
Clozapine is a highly effective atypical antipsychotic indicated for treatment-resistant schizophrenia. However, its use is limited by the risk of severe, life-threatening neutropenia and agranulocytosis. To mitigate this risk, prescribing clozapine in the United States requires enrollment in a strict Risk Evaluation and Mitigation Strategy (REMS) program. This protocol mandates monitoring of the absolute neutrophil count (ANC) on a highly scheduled basis: weekly during the first months of treatment, biweekly for the next months, and monthly thereafter if the ANC remains stable and within normal limits.
Step-by-Step Solution
Key Concept
Clozapine therapy requires strict, protocolized monitoring of the absolute neutrophil count (ANC) to prevent life-threatening severe neutropenia and agranulocytosis.