Restarting clozapine following leucopenia or neutropenia

Dunk et al (2006) report rechallenge with clozapine of people with either treatment-resistant or treatment-intolerant schizophrenia. A proportion of these may lack insight and capacity and may therefore be detained under the Mental Health Act 1983 but the authors do not indicate the proportion of patients in this group. If a person has been compulsorily detained, the treating clinician may require a second opinion from the Mental Health Act Commission. We are interested in whether Dunk et al have any data on this, as in the British National Formulary clozapine is contraindicated in those who have previously developed dyscrasia. The Mental Health Act Commission may not provide a second opinion for drugs that are contraindicated.

Dunk et al report a possible alternative explanation for dyscrasia during first exposure to clozapine in 25 patients. There was no alternative explanation in the remaining 28 patients. An obvious question that arises is whether a patient is more or less likely to develop dyscrasia on rechallenge if they have a history of an alternative explanation. This would be a very useful predictor and would be helpful when discussing the options with the patient prior to rechallenge.