PRESCRIBING

Published: 24/03/2005, Volume II5, No. 5947 Page 12

Michael Marven is chief pharmacist at Oxfordshire Mental Healthcare trust.

A five-month risk assessment study of switching 150 patients with treatment-resistant schizophrenia to a new brand of clozapine showed that the switch saved the trust about£170,000. The projected net savings across Thames Valley strategic health authority (about 450 patients) as a result of using Denzapine is estimated as£575,000.

The NHS as a whole could save about 40 per cent of the£55.5m a year it spends on clozapine. Some of this could then be ploughed back into treating more people with treatment-resistant schizophrenia with the drug, as recommended by the National Institute for Clinical Excellence.

At the time of the NICE guidance in June 2002, only the Clozaril brand was available and the manufacturers, Novartis, operated a sophisticated scheme to monitor changes in blood cells. NICE noted at the time: 'Routine monitoring is a prerequisite of clozapine use because of the risk of neutropenia and agranulocytosis.

Prescribers are therefore required to ensure that effective ongoing monitoring is maintained if alternative brands of clozapine become available.' With Clozaril, blood samples must be sent to a central laboratory and analysed. With the new brand, Denzapine, the samples can be sent either to a central laboratory or to the local acute hospital haematology laboratory alongside other pathology specimens. The monitoring of these test results is completed by the manufacturer of the drug, Denfleet Pharma.

Denfleet Pharma began a pilot study of its monitoring system in April 2004 in 12 centres with 1,649 patients. The Denfleet clozapine monitoring service is the national patient registry of patients taking Denzapine, and is a fundamental part of the treatment. It uses a colour-coded schedule to summarise blood results: green is normal, so treatment can continue; amber is the bottom range of normal, so treatment continues with caution; red is abnormal and treatment should cease.

A 24-hour patient monitoring service back-up team will provide courtesy reminders if blood samples and results are not submitted on time. A password-protected website enables healthcare professionals to check if patients are overdue for blood tests.

During the pilot-study period, 10 reds and 46 ambers were reported.