clozapine management

Question 1

Clozapine

Answer 1

atypical antipsychotic that is used for treatment-resistant schizophrenia.

Question 2

The drug is subject to strict monitoring requirements because it is associated with serious side effects, such as

Answer 2

neutropenia, agranulocytosis, seizures, myocarditis and cardiomyopathy

Question 3

incidence of neutropenia

agrunolocytosis

Answer 3

2% and agranulocytosis 0.8%

Question 4

percent that will respond to clozapine

Answer 4

30–60% of patients with treatment-resistant schizophrenia

Question 5

Pharmacists who encounter a prescription for clozapine should establish:

Answer 5

What brand of clozapine the patient is taking
The frequency of full blood count (FBC) tests and when the last one was taken
The current dose of clozapine
The patient’s adherence to clozapine treatment — specifically, whether he or she has missed a dose more than 48 hours beforehand
Who currently supplies the patient’s clozapine

Question 6

Brand of clozapine

Answer 6

Clozaril (Novartis)
Denzapine (Genus)
Zaponex (Teva UK)

Question 7

Timing of blood tests

Answer 7

Patients newly started on clozapine must have an FBC taken weekly for the first 18 weeks of treatment then fortnightly for the next 34 weeks. After that they receive monthly monitoring for as long as they are taking clozapine.

Question 8

ncidence of agranulocytosis per 100,000 person-weeks of observation
Weeks 0–18
Weeks 19–52
Weeks 53 and longer

Answer 8

Weeks 0–18 32.0
Weeks 19–52 2.3
Weeks 53 and longer 1.8

Question 9

amount of clozapine that can be supplied
weekly
fortnightly
monthly

Answer 9

Weekly FBC tests — maximum of 10 days’ supply of clozapine (from the date of the most recent blood test)
Fortnightly FBC tests — maximum of 21 days’ supply of clozapine (from the date of the most recent blood test)
Monthly FBC tests — maximum of 42 days’ supply of clozapine (from the date of the most recent blood test)

Question 10

Side effect monitoring
GREEN
AMBER
RED

Answer 10

WBC NEUTROPHIL
GREEN
Clozapine can be dispensed >3.5 >2.0
AMBER
Clozapine can be dispensed, but monitor full blood count twice a week 3–3.5 1.5–2.0
RED
Stop clozapine. Monitor full blood count daily until results return to normal* <3 <1.5

Question 11

Patients who have missed clozapine

Answer 11

Doses for more than 48 hours will need to have the medicine retitrated. They cannot continue taking their usual maintenance dose. If they miss more than three days of clozapine their blood testing frequency may need to change.

Question 12

Continuity of care

Answer 12

clozapine will be prescribed by a consultant psychiatrist and dispensed by a hospital pharmacy. A community pharmacy may be supplying clozapine under a service level agreement for patients receiving monthly blood tests.

Contact the supplying pharmacy to find out the patient’s current dose of clozapine, when he or she last collected supplies, the brand of clozapine and the directions prescribed. Clozapine often does not appear on GP records when a list of current medicines is obtained from a surgery. Ask patients whether they are receiving any other medicines apart from through the GP, especially if they have a diagnosis of schizophrenia and do not appear to be prescribed an antipsychotic.