Recently, ACP has been made aware of concerns about how pharmacy teams are handling clozapine prescriptions. Pharmacists are reminded about the following requirements for clozapine therapy.
Patients must be enrolled in a clozapine registry
Patients who are initiated on clozapine therapy – along with their treating physician and dispensing pharmacist – must be enrolled in a clozapine registry. Since 2003, there have been three manufacturers of clozapine (Novartis, Apotex, and GenCan), each with its own registry.
When patients enroll, the registry assigns a patient-specific number for tracking and monitoring. If a patient switches to a different treating physician, pharmacy, or laboratory, a modification form must be sent to the appropriate registry to notify them of the change.
Patients must undergo regular hematological testing
Patients must undergo regular hematological tests (i.e., complete blood count [CBC] + differential) to monitor their white blood cell count and absolute neutrophil count. The pharmacist must ensure that a CBC has been performed within the appropriate timeframe before dispensing clozapine. Weekly CBC is required of all patients on clozapine for the first 26 weeks, after which the frequency may be reduced to every two weeks.
Pharmacists must verify the patient’s non-rechallengable status
When dispensing clozapine for the first time, in addition to verifying the patient’s hematological status, the pharmacist should verify the patient’s non-rechallengable status. Pharmacists can call the clozapine networks to assess previous clozapine exposure and risk of agranulocytosis. If a patient is found to be non-rechallengable, they must not be restarted on any brand of clozapine.
Brands are not interchangeable
The three different brands of clozapine are not interchangeable. Health Canada specifically states that pharmacists must not switch a patient from one brand of clozapine to another unless they obtain a new, registry-specific patient registration form completed by the prescribing physician.
Additional resources
- Novartis (Clozaril Support and Assistance Network [CSAN])
- AASpire (The AA-Clozapine Patient Care Network)
- GenCAN (Gen-Clozapine Access Network)
