Using clozapine in adults and young people
Clozapine can only be started by a psychiatrist, after comprehensive assessment to determine if clozapine is suitable. This includes:
- checking for cardiovascular disease, epilepsy, haematopoietic disorders (particularly drug-induced neutropenia), other comorbidities that contraindicate clozapine use, smoking, caffeine intake
- measuring white cell count (must be more than 3.5 × 109/L), neutrophil count (must be more than 2.0 × 109/L), C-reactive protein (CRP), creatinine and urea, electrolytes, liver biochemistry, fasting lipids and blood glucose concentration
- undertaking cardiac investigations: electrocardiogram (ECG), echocardiogram and troponin levels
- measuring height and weight (to determine body mass index [BMI])
- checking temperature, blood pressure and heart rate
- reviewing drug therapy to identify potential interactions—consult a drug information resource.
For additional considerations in clozapine use, see:
- here for use in females of childbearing potential
- here for use during pregnancy
- here for use while breastfeeding—clozapine and concurrent breastfeeding should be avoided.
If clozapine is started for treatment-resistant schizophrenia, a typical regimen used by psychiatrists is:
clozapine 12.5 mg orally, in the morning on day 1, then increase over 14 days to a target daily dose of 200 mg (see Example clozapine dosage titration protocol). From day 14, the dosage can be increased according to response and tolerability up to a maximum daily dose of 900 mg. schizophrenia, treatment-resistant clozapine clozapine clozapine
Close monitoring of temperature, blood pressure, and heart and respiratory rate is required after starting clozapine; for comprehensive advice, refer to protocols available from clozapine manufacturers1 or the Australian Commission on Safety and Quality in Health Care National Inpatient Medication Chart.
|
Day |
Dose | |
|---|---|---|
|
morning |
evening | |
|
day 1 |
12.5 mg |
nil |
|
day 2 |
25 mg |
nil |
|
day 3 |
25 mg |
nil |
|
day 4 |
25 mg |
25 mg |
|
day 5 |
25 mg |
25 mg |
|
day 6 |
25 mg |
50 mg |
|
day 7 |
25 mg |
75 mg |
|
day 8 |
25 mg |
100 mg |
|
day 9 |
50 mg |
100 mg |
|
day 10 |
50 mg |
100 mg |
|
day 11 |
50 mg |
125 mg |
|
day 12 |
50 mg |
125 mg |
|
day 13 |
50 mg |
125 mg |
|
day 14 |
50 mg |
150 mg |
If clozapine therapy is interrupted for more than 48 hours, it must be restarted from 12.5 mg (see Example clozapine dosage titration protocol) to avoid severe sedation and respiratory depression.
All patients, prescribers and pharmacies must be registered with the clozapine monitoring database for the brand of clozapine used1. These databases collect data on white cell and neutrophil count, clozapine dispensing and dosage, and past adverse events. If white cell and neutrophil counts and infection screening have not occurred, clozapine cannot be dispensed. The brand of clozapine cannot be changed without changing registration to the appropriate database to maintain continuity of monitoring data.
After 18 weeks of therapy, provided the patient and clozapine dose are stable, an authorised medical practitioner under the supervision of a psychiatrist can prescribe clozapine but cannot adjust the dosage.