Clozapine - on the Level?

Abstract

Aim:

To discover whether clozapine is being prescribed and monitored according to accepted guidelines.

Method:

Sample size 30 with a diagnosis of Schizophrenia generated from a list of patients attending clozapine clinic. Clozapine levels were done prospectively from December 07 to March 08.

Results:

Of 30 patients, 73% were male and 27% female. 57% were prescribed >450 mg once daily and 50% had trough plasma levels >0.60mg/l. Only 21% were within the therapeutic range (as recommended by Clozapine Patient Monitoring System) 0.35-0.60 mg/l. 29% of patients had a plasma level < 0.35 mg/l. Only 10% had plasma levels checked within the last 6 months.Among 8 patients taking more than 600 mg of clozapine, 5 had an anticonvulsant prescribed prophylactically. among 14 patients with a plasma level >0.60 mg/l, only five had an anticonvulsant co-prescribed.

Discussion:

The outcome of this audit has wide implications from a medico-legal perspective. There is significant evidence implicating clozapine in the development of metabolic syndrome as well as potentially serious side effects including seizures. It is important that clozapine plasma levels are checked when therapeutic doses (Maudsley guidance: 450mg once daily) are reached and that anticonvulsant prophylaxis is considered at high plasma levels.