All patients taking clozapine must have their blood monitored before starting and throughout the course of clozapine therapy to mitigate the risk of agranulocytosis. The patients, their treating physicians, and dispensing pharmacists must be enrolled in manufacturer-specific registries. Pharmacists may not unilaterally switch patients from one brand to another.
The registries are specific to each market authorization holder. Health Canada has set the following policies in place should a patient need to change brands.
Policies for switching
- The switching of a patient from one brand of clozapine to another must not be done by a pharmacist unless he/she obtains a new, registry-specific patient registration form filled out by the prescribing physician.
- The physician has to inform his/her patient about the potential sharing of information between clozapine registries and document if there is consent from the patient to allow it, to ensure the safe use and continuous monitoring of patients taking clozapine.
- The responsibility of physicians concerning the sending of the mandatory laboratory results (white blood cell counts an differential) to the appropriate registry will be limited to informing the laboratory where the patient’s haematological results have to be sent.
- Weekly monitoring of neutrophils and white cell counts for four weeks at the end of the treatment is necessary only in the case of cessation of all clozapine treatment.
ACP has received concerns that some community pharmacists may be unilaterally switching patients from one brand of clozapine to another. This practice is contrary to the federal requirements.